Htp Drain back Installation manual

Drain Back

Solar Systems

Installation

Start-Up

Maintenance

Parts

Warranty

For Residential and Commercial Use

DB Models

272 Duchaine Blvd. New Bedford, MA 02745 www.htproducts.com

lp-585 Rev. 000 Rel. 001 Date 9.10.18

NOTE TO CONSUMER: PLEASE KEEP ALL INSTRUCTIONS FOR FUTURE REFERENCE.

The solar energy system described in this manual, when properly installed and maintained, meets the minimum standards

established by the SRCC. This certication does not imply endorsement or warranty of this product by the SRCC.

This manual must only be used by a qualied installer /

service technician. Read all instructions in this manual

before installing. Perform steps in the given order. Failure to

do so could result in substantial property damage, severe

personal injury, or death.

HTP reserves the right to make product changes or updates

without notice and will not be held liable for typographical

errors in literature.

The surfaces of these products contacted by potable

(consumable) water contain less than 0.25% lead by weight

as required by the Safe Drinking Water Act, Section 1417.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

The following dened terms are used throughout this manual to

bring attention to the presence of hazards of various risk levels or to

important product information.

DANGER indicates an imminently hazardous situation which, if not

avoided, will result in serious personal injury or death.

WARNING indicates a potentially hazardous situation which, if not

avoided, could result in personal injury or death.

CAUTION indicates a potentially hazardous situation which, if not

avoided, may result in moderate or minor personal injury.

CAUTION used without the safety alert symbol indicates a

potentially hazardous situation which, if not avoided, may result in

property damage.

NOTICE is used to address practices not related to personal injury.

Foreword

For the Installer

Table of Contents

Introduction 3

Part 1 - General Safety Information 3

A. When Servicing the Solar Water Heating System 4

B. Local Installation Regulations 4

C. Chemical Vapor Corrosion 4

D. Insulation Blankets 4

E. Water Temperature Adjustment 4

F. Freeze Protection 4

Part 2 - Important Information 5

A. Scope of this Manual 5

B. Local Standards and Authorized Persons 5

C. Terminology 5

D. System Design 5

E. Fluid Quality 5

F. Corrosion 5

G. Freeze Protection 5

Part 3 - General Solar Information 5

A. System Description 5

B. System Design 6

C. Solar Collector Installation 6

D. Collector Angle, Plane, and Direction 6

1. Collector Direction 6

2. Collector Angle (Tilt) 6

3. Collector Plane (Horizontal or Vertical) 6

E. Collector Piping 6

F. Collector Loop Pipe Insulation 7

G. Collector Sensor Placement 7

H. Avoid Shade 7

I. Location 7

J. Lightning Protection 7

K. Galvanic Reaction 7

L. Wind Stress 7

M. Snow Load 7

N. Hail Resistance 8

O. Storage Tanks 8

P. Sizing the Drain Back Tank 8

For your safety, please read through this manual carefully before

installation to minimize the risk of re, property damage, personal

injury, or death. Ensure the solar hot water system is properly

installed in accordance with this manual before use.

INSTALLATION OR SERVICE OF THIS SOLAR SYSTEM IS REQUIRED

TO BE PERFORMED BY LICENSED PROFESSIONALS WHERE SOLAR,

PLUMBING, AND ELECTRICAL WORK IS REQUIRED.

The installer should be guided by the instructions furnished with

the tank, as well as local codes and utility company requirements.

Preference should be given to codes and requirements where they

dier from the furnished instructions. Always use the latest edition

of codes.

Additional publications which should guide the installer include:

Local, state, provincial, and national codes, laws, regulations, and

ordinances.

Solar Water Heating System Design and Installation Guidelines, SRCC

OG-300, available from Solar Rating & Certication Corporation,

400 High Point Drive, Suite 400, Cocoa, FL 32926-6630, www.solar-

rating.org.

The latest version of the National Electrical Code, NFPA No. 70.

In Canada refer to Canadian Electrical Code C 22.1, from Canadian

Standards Association, 5060 Spectrum Way, Suite 100, Mississauga,

Ontario, Canada L4W 5N6.

For Your Records

Write the Product Model and Serial Numbers:

Model # ___________________________________________

Serial # ____________________________________________

These numbers are listed on the product ratings label.

Keep this manual and information for future reference.

This manual is intended to be used in conjunction with other literature

provided with the Solar Water Heater. This includes all related control

information. It is important that this manual, all other documents

included with this system, and additional publications, such as Solar

Water Heating System Design and Installation Guidelines, SRCC OG-300,

be reviewed in their entirety before beginning any work.

“The solar energy system described in this manual, when properly

installed and maintained, meets the minimum standards established

by the SRCC.This certication does not imply endorsement or warranty

of this product by the SRCC.”

The design of this solar system is approved by the Solar Rating and

Certication Corporation (SRCC). Any deviation from the approved

specied SRCC components may aect your ability to certify this

system.

Installation should be made in accordance with the regulations of

the Authority Having Jurisdiction, local code authorities, and utility

companies which pertain to this type of water heating equipment.

Authority Having Jurisdiction (AHJ) – The Authority Having Jurisdiction

may be a federal, state, local government, or individual such as a re

chief, re marshal, chief of a re prevention bureau, labor department

or health department, building ocial or electrical inspector, or others

having statutory authority. In some circumstances, the property owner

of his/her agent assumes the role, and at government installations, the

commanding ocer or departmental ocial may be the AHJ.

NOTE: HTP, Inc. reserves the right to modify product technical

specications and components without prior notice.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

Introduction

Drain back tanks are designed to allow solar collectors and related

piping to drain heat transfer uid into the drain back reservoir when

not in use.

Drain back systems are versatile: ideally suited for both cold and warm

regions.The drain back process protects solar system components from

both freezing and overheating, and saves power by shutting down the

solar system when there is no longer a demand for hot water. Drain back

systems have fewer components than pressurized systems, making

drain back systems easier to use, service, and maintain. The drain back

tank ships without a heat exchanger for use with a solar water heater

with an internal heat exchanger.

This manual intends to familiarize you with the proper installation and

maintenance of your solar water heating system. This system must

be installed by a licensed solar or plumbing contractor in accordance

with SRCC Standard OG-300 and all applicable national, state, and local

codes.

NOTE: Solar system performance and eciency varies with factors such

as: household hot water load, ambient air temperature, collector/roof

pitch, collector orientation, and seasonal intensity.

Job site conditions will require your installation contractor to supply

some or all of the following:

• Plumbing connections

• Piping and insulation

• Valves between the existing domestic water system and the

drain back solar system

Part 1 - General Safety Information

Installer - Read all instructions in this manual before installing.

Perform steps in the given order.

User - This manual is for use only by a qualied heating installer /

service technician. Have this solar water heating system serviced /

inspected annually by a qualied service technician.

Failure to adhere to these guidelines can result in substantial

property damage, severe personal injury, or death.

NOTE: Obey all local codes. Obtain all applicable permits before

installing the solar system.

NOTE: Install all solar system components and piping in such a

manner that does not reduce the performance of any re rated

assembly.

Part 4 - Installation 8

A. Checklist 8

B. Tools and Materials 8

C. Locating the Drain Back Tank 8

D. Specications and Dimensions 9

Part 5 - Piping 9

A. Potable Water Piping 9

B. Water Chemistry Requirements 10

C. Solar Heat Exchanger Piping 10

D. Necessary Components for Water Heater Installation 10

E. Installation of the Drain Back Tank 11

F. Solar System Pump 12

G. Electrical Installation 12

H. Installing the Drain Back Tank Sight Tube 12

I. Applications 13

Part 6 - Fluid Quality 15

A. Solar Loop Fluid Quality 15

B. Fluid Safety Labeling 15

C. Freeze Protection 15

Part 7 - Start-Up Preparation 15

A. Check for Leaks in the Solar Loop 15

B. Fill the Drain Back Reservoir 15

C. Start-Up Procedure 15

Part 8 - Service / Maintenance Procedures 15

A. Shutdown Procedures 16

B. Draining the Drain Back Reservoir 16

C. Routine Maintenance 16

D. Vacation Shutdown Procedure 16

E. Estimated Life of Components 16

F. Temperature and Pressure Relief Valve 16

Part 9 - Troubleshooting 16

A. Leaks 16

B. Other Problems 16

C. Operating Suggestions for the User 16

Part 10 - System Parts Listing 17

A. Estimated Component Life 17

B. Warranties and Disclaimers 17

Limited Warranty 25

Customer Installation Record Form 27

DO NOT USE THE SOLAR SYSTEM IF ANY PART HAS BEEN

SUBMERGED IN WATER. Immediately call a qualied service

technician. Components may need to be replaced. Attempting

to operate components that have been submerged could create

numerous harmful conditions, such as a potential gas leakage

causing a re and/or explosion, or the release of mold, bacteria,

or other harmful particulates into the air. Operating a previously

submerged water heater could result in property damage, severe

personal injury, or death.

NOTE: Damage due to ood or submersion is considered an Act of

God, and IS NOT covered under product warranty.

NOTE: Failure to follow the procedures and instructions in this manual

WILL VOID the warranty.

High heat sources (sources generating heat 100oF / 37oC or greater,

such as stove pipes, space heaters, etc.) may damage plastic

components of the water heater as well as plastic vent pipe materials.

Such damages ARE NOT covered by warranty. It is recommended to

keep a minimum clearance of 8”from high heat sources. Observe heat

source manufacturer instructions, as well as local, state, provincial,

and national codes, laws, regulations and ordinances when installing

this water heater and related components near high heat sources.

NOTE: If the solar water heating system is exposed to the following,

do not operate. Immediately call a qualied service technician.

1. Fire

2. Damage

3. Submersion in Water

Failure to adhere to these guidelines can result in substantial

property damage, severe personal injury, or death.

Only use this solar hot water system as intended and described

in this installation manual. Any use other than described will void

warranty and may lead to re, property damage, personal injury, or

death.

Improper installation or use may result in property damage. Such

damages ARE NOT covered by warranty.

Ensure there are no low points or dips in sloped non-vertical supply

and return pipe runs from the solar collectors to the drain back tank.

Low points and improperly designed solar piping can trap water and

possibly rupture in freezing weather. Pitch non-vertical piping ¼”per

foot towards the drain back tank to facilitate proper drainage, and

take care to properly layout piping to ensure there are no low points.

In addition, the drain back tank and solar storage tank must be

protected from freezing temperatures. Care must be taken when

lling the system to avoid overlling and exposing pipes to a

freezing condition.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

A. When Servicing the Solar Water Heating System

To avoid electric shock, disconnect electrical supply before performing

maintenance.

To avoid severe burns, allow solar collector and associated equipment

to cool before servicing.

ALL PIPING AND PLUMBING CONNECTIONS SHOULD BE MADE

WITH COPPER PIPE ONLY. No less than ¾” I.D. copper tube of the

type meeting local codes must be used for piping. Pipe runs must be

solidly attached with proper clamping methods. Soldered connections

should be secured with 95/5 lead-free solder. Use only pipe rated for

250oF minimum on both the collector return and supply piping.

PEX piping is approved for use in the solar loop of drain back systems

ONLY.

B. Local Installation Regulations

Installation of this solar water heating system may be governed

by individual local rules and regulations for this type of system,

which must be observed. Always use the latest edition of codes. The

installation, adjustment, service, and maintenance of the solar water

heater must be done by a licensed professional who is qualied and

experienced in the installation, service, and maintenance of solar hot

water systems.

UNCRATING SYSTEM COMPONENTS - Any claims for damage

or shortage in shipment must be led immediately against the

transportation company by the consignee.

C. Chemical Vapor Corrosion

Products to Avoid Areas Likely to Have

Contaminants

Spray cans containing

uorocarbons

Dry cleaning / laundry areas

and establishments

Permanent wave solutions Swimming pools

Chlorinated waxes / cleaners Metal fabrication plants

Chlorine-based swimming pool

chemicals Beauty shops

Calcium chloride used for thawing Refrigeration repair shops

Sodium chloride used for water

softening Photo processing plants

Refrigerant leaks Auto body shops

Paint or varnish removers Plastic manufacturing plants

Hydrochloric or Muriatic acid Furniture renishing areas and

establishments

Cements and glues New building construction

Antistatic fabric softeners used in

clothes dryers Remodeling areas

Chlorine-type bleaches, laundry

detergents, and cleaning solvents Garages and workshops

Adhesives used to fasten building

products

Table 1 - Products and Areas Likely to Have Contaminants

NOTE: DAMAGE TO THE DRAIN BACK TANK, SOLAR SYSTEM, OR

RELATED COMPONENTS CAUSED BY EXPOSURE TO CORROSIVE

VAPORS IS NOT COVERED BY WARRANTY. (Refer to the limited

warranty for complete terms and conditions.)

D. Insulation Blankets

For installation of insulation blankets, refer to Solar Water Heating

System Design and Installation Guidelines, SRCC OG-300.

E. Water Temperature Adjustment

An ASSE 1017 rated mixing valve to avoid severe burns or death

from scalding temperatures IS REQUIRED PER SRCC OG-300.

Approximate Time / Temperature Relationships in Scalds

120oF More than 5 minutes

125oF 1 1/2 to 2 minutes

130oF About 30 seconds

135oF About 10 seconds

140oF Less than 5 seconds

145oF Less than 3 seconds

150oF About 1 1/2 seconds

155oF About 1 second

Table 2 - Approximate Time / Temperature Relationships in Scalds

Households with small children, disabled, or elderly persons may

require a 120oF or lower temperature setting to prevent severe

personal injury or death due to scalding.

In addition, to prevent scalding, the high temperature of the potable

water must be limited using an ASSE 1016 tempering valve. This

valve is usually located between the hot water storage tank and

faucets in bathrooms, kitchens, etc. Tempering valves are mandatory

under most codes and usually set to a maximum of 120oF. Tempering

valves must be rated for high-temperature solar use.

F. Freeze Protection

NOTE: Consider piping and installation when determining drain

back tank location. Place tank in a location not prone to freezing.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

Failure of the drain back tank, solar system, or components due to

freeze related damage IS NOT covered by product warranty.

Part 2 - Important Information

A. Scope of this Manual

This manual pertains only to the installation and operation of

the drain back tank. Details for the installation, operation, and

maintenance of the complete solar water heating system, including,

but not limited to: the solar collector(s), storage tank, gas booster,

pump, system controller, valves, and other plumbing components,

should be provided separately by their respective manufacturers.

NOTE: This manual is primarily a reference document for authorized

installation individuals, as the drain back tank is not permitted to be

installed by non-authorized persons.

In order to meet health and safety regulations, solar system

antifreeze uid should be food grade polypropylene glycol, FDA

rated as “generally recognized as safe” (GRAS). The recommended

glycol is DOWFROST or equivalent. Using proper concentrations of

glycol, solar systems can be operated at ambient temperatures as

low as -60oF. Freeze tolerance limits are based upon an assumed

set of environmental conditions. Refer to the specication sheet

included with the glycol for recommended concentrations. A glycol

/ potable water mix must not exceed 50%, unless the manufacture

species that a dierent ratio is recommended for use with solar

water heaters. Glycol may need to be changed periodically

(every 3-5 years) to prevent it from becoming acidic; please refer

to the guidelines provided by the glycol manufacturer regarding

replacement.

B. Local Standards and Authorized Persons

Installation must be completed in accordance with local standards

and regulations.

Installation must also be completed by a qualied tradesperson

who holds relevant industry licenses or certicates. The term

“authorized person(s)” used throughout this document refers to a

suitably qualied professional. Unless otherwise specied, no part

of the drain back tank may be inspected, repaired, or maintained by

anybody other than an authorized person.

C. Terminology

Solar terminology diers from region to region. To avoid confusion,

please note the following:

Supply – The plumbing line running from the outlet of the solar

collector to the drain back tank and solar water heater.

Return – The plumbing line running from the solar water heater to

the inlet of the collector. This line incorporates the circulation pump.

D. System Design

Drain Back Systems

The drain back method provides eective overheating and freeze

protection, making these systems well-suited for all climates. When

storage tank water temperature settings are reached or the collector

temperature falls below a set temperature, the pump shuts o,

allowing the HTF to drain back into the tank. Drain back systems use

potable water or a glycol / potable water mix as HTF.

Drain back systems require larger pumps to move HTF up and into

the solar collectors. Mounting the drain back tank as high as possible

within conditioned space will reduce pump size.

For drain back systems, the solar loop often operates at less than

25 psi, far lower than open or closed loop systems. These low

operating pressures do not require an expansion tank. A pressure

relief valve, installed on the drain back tank and piped in copper to

an appropriate drainage location, will provide sucient expansion

protection. This pressure relief valve and drain outlet pipe must

never be sealed or blocked. The pressure relief valve is intended to be

operated for safety purposes only.

NOTE: Supply and return connections to the collector must use

eccentric ttings or a tting arrangement that allows full draining

of header pipes. The collector or array must be mounted at ¼” pitch

towards the supply port to facilitate the drain back process. In addition,

collector plumbing should slope toward the drain back reservoir at

¼” per foot minimum to facilitate the drain back process. If continual

slope is not achievable, consider a pressurized closed loop system.

E. Fluid Quality

Water quality is very important. Water in direct ow through the

solar collectors must rst meet potable water requirements; any uid

circulated through the collectors should be non-corrosive to copper. In

addition, water quality must meet the following requirements.

Total Dissolved Solids < 500 ppm

Total Hardness < 7 grains (120 ppm)

Chloride < 100 ppm

pH Levels 6.5 - 8.5

Table 3 - Water Quality Requirements

In order to meet health and safety regulations, glycol used should be

food grade propylene glycol, FDA rated as “generally recognized as

safe” (GRAS). If using a glycol / potable water mix, the water must meet

the above requirements. The glycol content of the liquid must not

exceed 50%, unless the manufacturer species that a dierent ratio

is recommended for use with solar water heaters. Glycol should be

checked periodically to prevent it from becoming acidic. Please refer

to guidelines provided by the glycol manufacturer regarding glycol

maintenance.

F. Corrosion

Both copper and stainless steel are susceptible to corrosion when,

amongst other factors, high concentrations of chlorides are present.

NOTE: Leakage of the drain back tank due to corrosion caused by

improper water quality IS NOT covered by product warranty.

G. Freeze Protection

Though drain back systems provide freeze protection by allowing HTF

from the solar collectors to drain into a reservoir in freezing conditions,

it is important to locate the drain back tank in a location not prone

to freezing conditions. Freeze protection must be implemented in

any regions that may experience freezing conditions at any time

throughout the year.

“Freeze tolerance limits are based upon an assumed set of

environmental conditions. Extended periods of cold weather, including

ambient air temperatures below the specied limit, may cause

freezing in exposed parts of the system. It is the owner’s responsibility

to keep the system’s freeze protection levels maintained in accordance

with the supplier’s instructions if the air temperature is expected to

approach the specied freeze tolerance limit.”

Part 3 - General Solar Information

A. System Description

By using the sun’s energy to heat water, solar hot water heating systems

help reduce the nation’s dependence on polluting fossil fuels. This

reliable, ecient drain back tank meets the certication requirements

of SRCC-OG-300.

Basic components of a drain back solar water heating system include:

the solar collector(s), a solar water heater, a circulator pump, and a

dierential solar control.

Drain back solar systems use potable water or a glycol / potable water

mix as a heat transfer uid (HTF) and operate in a closed loop. A drain

back reservoir tank allows the solar collector(s) to drain HTF when not

in use, protecting the system from both freezing and overheating. HTP

lp-585 Rev. 000 Rel. 001 Date 9.10.18

solar hot water heaters provide a backup when solar contribution is

limited due to adverse weather conditions.

Do not introduce HTF into any ttings on the heater except those

clearly marked for that purpose.

B. System Design

System design should be completed prior to installation. Solar

collectors need to be installed correctly to ensure high eciency and,

most importantly, safe and reliable operation. Please seek professional

advice for the design and installation of your solar heating system.

NOTE: Only authorized licensed contractors are permitted to install

the solar collector.

C. Solar Collector Installation

NOTE: These solar collector instructions are general in nature.

Reference the solar collector manufacturer’s instructions for more

specic and detailed installation information.

The solar collector installation contractor shall obtain all required

permits and approvals when installing the solar system. The installation

shall conform to all federal, state and local regulations governing

solar water heating system installations. The contractor shall adhere

to sound building safety and trade practices. Special consideration

must be given to building code requirements for the penetration of

structural members and re rated assemblies.

All persons working on roofs should have completed a fall safety

course and must be properly outtted with appropriate safety

equipment. Failure to follow this information could result in property

damage, severe personal injury, or death.

Before installation, the contractor shall inspect the condition of

the roof and notify the homeowner of any existing roof damage or

necessary repairs. The most important structural consideration is to

securely anchor the solar collector and solar strut mounting hardware

to the structural members of the roof with stainless steel hanger or lag

bolts. Consult with the collector manufacturer installation manual for

proper guidelines in your application.

Solar collectors should be covered at all times until installation is

complete. Failure to follow this information could result in severe

personal injury or death.

Preserving the integrity of the roof membrane is the most important

roong consideration. Ensure that all roof penetrations required to

plumb and mount the solar collector are properly ashed and sealed

in accordance with standard roong practices. The recommended

elastomer for sealing roof penetrations is Tremco“POLYroof”.

D. Collector Angle, Plane, and Direction

1. Collector Direction

The collector should face the equator. In the northern hemisphere,

this is due south, and in the southern hemisphere, due north. Facing

the collector in the correct direction and angle is important to ensure

optimal heat output. A deviation of up to 15ofrom due south is

acceptable, and will have minimal eect on heat output.

Mounting Methods:

A, B - Sloped Roof

C - Flat Roof

D - Facade

Figure 1 - Suggested Solar Collector Mounting Designs

2. Collector Angle (Tilt)

It is common for collectors to be installed at an angle that corresponds

to the installation latitude.While adhering to this guideline, an angle of

latitude +/- 10ois acceptable, and will not greatly reduce solar output.

The solar collector should be installed at an angle between 20 – 80oto

ensure optimal operation.

For year-round domestic hot water, the collector should be tilted to

an angle of equal to the latitude of the installation site. Add 15oto

3. Collector Plane (Horizontal or Vertical)

The collector could be installed vertically, but may be installed at an

angle, such as sideways on a pitched roof. It is not recommended

to install a drain back system in the horizontal or landscape style.

In vertical installations, collectors may be installed with 1/4” pitch

towards the supply port to facilitate the drain back process.

E. Collector Piping

Collector piping in drain back systems may be constructed of

copper and brass ttings, or PEX.

Systems Piped in Copper

To avoid leaks and uid loss, copper and brass ground joint unions

should be used to join the collectors. Use only lead-free solder.

Engelhard Silvabrite 100 or equivalent is the required soldering

material. Use of 50/50 lead solder is expressly prohibited. Use of

galvanized steel, CPVC, PVC or any other nonrated plastic pipe is

prohibited.

Systems Piped in PEX

• The PEX shall not be exposed to sunlight.

• Drain back systems employing PEX shall be non-pressurized

(capped at atmospheric on the day of installation) or the

system shall be vented to the atmosphere.

• At the inlet and outlet of the collector(s), a length of

uninsulated copper tube of no less than ¾” nominal

diameter shall be used for a distance of no less than three

feet before the conversion to PEX for the return line is made.

• Connections in the PEX piping runs to and from the collectors

shall use only those ttings supplied and/or approved by

the PEX manufacturer for potable water piping.

• The systems shall have a pressure-only relief valve installed

at the drain back tank location or the tank shall be vented to

the atmosphere. The pressure rating for this valve shall be

no less than 25 psi and no more than 50 psi.

Never use dielectric unions or galvanized steel ttings in the

collector loop. Doing so will lead to corrosion, property damage,

and possible early water heater failure. Such damage IS NOT

covered by warranty. Use only copper and brass ttings.

the latitude to optimize for winter performance (space heating).

Subtract 15ofrom the latitude to optimize for summer performance

(indirect pool heating).

Given the formula above, a solar collector installed at 30oN latitude

should face due south at an angle of 45ofor wintertime advantage,

and 15ofor summertime heating.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

F. Collector Loop Pipe Insulation

The collector loop supply and return lines must be well insulated

with high quality, exible, closed cell insulation to minimize heat

loss. Wall thickness of pipe insulation should not be less than ¾”. 1”

wall thickness is required in all areas prone to annual hard freeze

conditions. When it comes to pipe insulation the rule is simple:

thicker is better. The specied insulation material is HT/Armaex or

equivalent.

Whenever possible, slide the insulation material over the pipe

without cutting or taping. All butt joints must be sealed with

contact adhesive. HT/Armaex should be sealed with Armaex HT

625 adhesive. Use of rigid polyethylene pipe insulation is prohibited.

Temperatures generated by your collector in the summer months or

under stagnation conditions can melt this type of material.

Any above ground exterior pipe insulation is subject to UV

degradation and must be wrapped with PVC pipe wrap or painted

with two coats of high quality water-based acrylic resin coating as

supplied by the insulation manufacturer. Foil tape should not be

used as it will fail. The required coating material is Armaex WB

Finish or equivalent. Prior to applying nish, wipe insulation clean

with denatured alcohol. Paint insulation with two coats of nish. Do

not tint the nish.

• If the collector stagnation temperature is below 210oF, PEX

can be used without a length of copper pipe between the

collector and the PEX.

Penetrations through walls or other surfaces shall not allow

intrusion by insects and/or other vermin. Ensure that all structural

penetrations are properly sealed with an elastomer, such as Tremco

“POLYroof”.

Piping in new solar installations may have dirt, grease, solder

ux, or other impurities that will aect the quality of HTF over

time. Thorough cleaning is required before charging new solar

installations with glycol.

All vertical piping between the drain back tank and collector shall

be supported at each story or at maximum intervals of ten (10) feet.

In addition, all non-vertical solar collector piping should pitch 1/4”

per foot down to the drain back tank to facilitate proper drainage.

Ensure that there are no dips or low points in solar piping that

could trap uid and possibly rupture in freezing conditions. Copper

plumbers tape or tube strap is the required strapping material. The

pipe insulation may not be compressed or crimped by the strapping

material.

The installation of all piping may not reduce the performance or

rating of structural members or re rated assemblies and must

adhere to all applicable local codes and ordinances.

G. Collector Sensor Placement

The collector sensor must be located on the hot water return line

as close to the collector as possible. Some collectors have insertion

wells to measure temperatures more accurately at the manifold.

Sensors are typically accurate to +/– 1/2 °F if properly installed

and weatherized. To maximize sensor accuracy, attach the anged

portion of the sensor to the collector header pipe with a stainless

steel hose clamp. Wire nuts used to connect the sensor and low

voltage wiring shall be all plastic, sealed with silicone and thoroughly

wrapped in electrician’s tape.

The low voltage wiring used to connect the sensors to the controller

should be a minimum 18 AWG. The wiring should be bare or tinned

copper, two conductor, PVC insulated, with a PVC UV rated gray

jacket suitable for exterior use. Use Eastman Wire & Cable no. 5704,

Beldon Wire and Cable no. 8461 or equivalent.

The sensor must be placed on the solar collector hot out line as

close to the collector header as possible, or inserted into a sensor

well near the hot out line. Place the sensor wire over the rubber pipe

insulation, under the insulation tape or PVC pipe wrap. Thoroughly

wrap and weatherize the insulation with electrician’s tape or insulation

tape as provided by the manufacturer.

Figure 2 - Sensor Cable Detail

H. Avoid Shade

Collectors should be located so that shading does not occur between

9 AM and 3 PM local time. Partial shading due to small objects such as

antennas and ues is not of great concern.

I. Location

To avoid long pipe runs, the collector should be positioned as close as

possible to the storage tank. Storage tank location should therefore

be considered part of the location requirements of the solar collector.

The storage tank should be located as close as possible to the most

frequent draw o points in the building.

J. Lightning Protection

To avoid lightning related damage or electrical safety issues, it is

advisable to earth/ground the frame and copper circulation loop of

the collector.

K. Galvanic Reaction

Zinc galvanized components should NOT be installed in direct

contact with stainless steel or aluminum, as galvanic reaction

between metals can cause premature oxidation of the zinc coating,

as well as the steel and aluminum underneath. This reaction could

lead to structural failure, property damage, severe personal injury,

or death.

Avoid using galvanized steel bolts. Use stainless steel components

instead. If galvanized components ARE used, avoid direct contact

between two metals by using rubber/plastic separators.

If roof surface is galvanized steel, refer to manufacturer’s corrugated

roof installation guidelines.

L. Wind Stress

When installing the solar collector(s), please consider the issue of

wind resistance and the resultant stress on attachment points. Adhere

to relevant building codes/regulations regarding installation of such

objects.

It is the responsibility of the installation contractor to ensure that the

frame mounting is of suitable strength. Where applicable, inspection

by building department ocer or equivalent should be completed to

ensure the installation is in accordance with relevant regulations.

M. Snow Load

In areas prone to heavy snowfall, the solar collector(s) should ideally

be installed at an angle of 50° or greater to help promote snow sliding

o the collectors. In addition, it is advisable to raise the lower collector

frame o the roof surface 6 – 8 inches or higher. Doing this places the

collector above moderate snowfall accumulation and allows drifting

snow to more easily slide out from under the collector, which helps

ensure that snow does not cover the collector array.

Please refer to local regulations regarding snow loading precautions.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

N. Hail Resistance

Solar collectors are surprisingly strong and able to handle signicant

impact stresses once installed. Testing and impact stress modeling

proves that when installed at an angle of 40oor greater, collectors

are able to withstand impact from hail larger than 1” in diameter. The

ability of collectors to withstand hail impact is greatly inuenced by

the angle of impact, so installing the collectors at low angles does

reduce their impact resistance.

O. Storage Tanks

It is recommended that the lever on the pressure and temperature

relief valves (PTRV) on main pressure hot water storage tanks be

operated once every 6 months to ensure reliable operation. It is

important to raise and lower the lever gently, and be careful as the

water released will be HOT. Failure to operate the PTRV on a regular

basis could lead to failure of the component and the possibility of the

storage tank exploding.

It is recommended, and may also be a local regulation, that, in order to

expel water safely, the PTRV have a copper pipe connected and run to

an appropriate drainage location. The PTRV and drain outlet pipe must

not be sealed or blocked.

NOTE: If the water heater is left in an operating condition and not used

for two weeks or more, a quantity of highly ammable hydrogen may

accumulate in the top of the water cylinder.

To dissipate hydrogen safely, it is recommended that a hot water tap

be turned on for several minutes at a sink, basin, or bath, but not

a dishwasher, clothes washer, or other electrical or heat producing

appliance. During this process, there must be no smoking,

open ame, or electrical appliance operating nearby. Hydrogen

discharged through the tap will sound like air escaping. Failure

to dissipate hydrogen properly could result in explosion and re,

serious property damage, severe personal injury, or death.

P. Sizing the Drain Back Tank

Part 4 - Installation

A. Checklist

Location

• Sucient room to service drain back tank, piping, and related

controls

• Provisions made to protect area from water damage

• Centrally located to xtures

• Protected from freezing temperatures

• Area free of ammable and/or corrosive vapors

Potable Water Supply

• All related piping free from leaks

• Thermal expansion tank installed

• Water heater and xtures have been properly purged of air

• ASSE 1017 rated thermostatic mixing valve IS REQUIRED PER

SRCC OG-300

B. Tools and Materials

The following is a minimum list of basic required tools. Other

plumbing components will be eld supplied according to

installation needs.

COLD WEATHER HANDLING - If the water heater has been stored

in a very cold location (BELOW 0oF) before installation, handle

with care. Failure to do so could result in damage to the water

heater.

Electric Drill

Drill Index (w/ 1/2”,

3/4”, 1”, and 1 1/4”

Wood Bits)

Torch and Striker

Putty Knife Hack Saw High Temperature

Joint Compound

Tubing Cutter Tin Snips Solder Flux

Tape Measure Emory Paper 24” Level

Extension Cord Slip Joint Pliers Needle Nose Pliers

Silicon Caulk and

Roof Tar

Pipe Wrenches, 10”

and 14” Angle Iron

Open End Wrenches

9/16 & 7/16

Screw Driver 6”Flat

Blade

Screw Driver 6”

Phillips

Wire Stripper or

Knife Wire Cutters Black Latex Outdoor

Paint

Adjustable

Wrenches 8”& 10”

Aluminum

Flashing Sheet Flashlight

Extension Cord Wire Nuts or

Connectors

Threaded Rod, Nuts,

and Washers

Miscellaneous

Copper Pipe and

Fittings (3/4”)

1” x 3/4” Copper

Sweat Couplings

1” Copper Sweat

Caps

Minimum 3/4” ID

Type M Copper

Tubing

Stainless Screw

Clamps Thermal Adhesive

7/8” x 3/4” and 1

1/8” x 3/4” Pipe

Insulation

Table 4 - Basic Required Tools

C. Locating the Drain Back Tank

This drain back tank is certied for indoor use only. DO NOT INSTALL

OUTDOORS. Outdoor installations ARE NOT covered by warranty.

To minimize expense, choose a location for the drain back tank as

To ensure proper operation of the drain back solar system, the drain

back tank volume should be sized with double the volume capacity of

the total volume of the solar collectors and all solar piping above the

drain back tank.

For example:

An HP-30SC Evacuated tube solar collector has a .3 gallon capacity.

100 feet of 1”copper pipe has a 4.6 gallon capacity.

The capacity of the collector and piping equals 4.9 gallons.

The system requires a 10 gallon drain back tank.

• Have water supply tested and ensure it meets the

requirements outlined in this manual

Relief Valve

• Temperature and Pressure relief valve properly installed and

discharge line runs to open drain

• Discharge line not exposed to freezing temperatures

• Discharge line constructed of copper

Anti-Freeze Fluid (If Used in System)

• Make sure freeze protection uids are certied non-toxic,

FDA rated GRAS

• Glycol percentage must be calculated per local area freeze

level

• Provide glycol MSDS sheet to end user

NOTE: Make sure you have all necessary tools, materials and

accessories before beginning work on the solar system.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

centralized to the solar tank and domestic piping system and near

the solar collectors as possible. Also, locate the tank in as warm a

location as possible, away from areas which would subject the drain

back tank reservoir to freezing temperatures. All piping should be

insulated to protect against freezing and minimize heat loss.

Additionally, the drain back tank, solar water heater, and all

related solar system components should be installed with plenty

of clearance for inspection and service. If minimum clearances are

not met, it may not be possible to service the solar system without

removing components from installation locations.

The drain back tank should also be installed in a place where T&P

discharge or a leak will not result in damage to the surrounding area.

Install a 2”high drain pan with a minimum of ¾”drain line to prevent

water damage if leakage should occur. See Figure 3.

Figure 3 - Recommended Service Clearances

Filled hot water storage and drain back tanks are very heavy, and

should be located in areas that can structurally support such

weight. Failure to properly locate water storage tanks could result

in property damage, personal injury, or death.

D. Specications and Dimensions

TANK INLET

Figure 4 - Drain Back Tank without Heat Exchanger Specications and

Dimensions

This tank must be installed upright in the vertical position as

described in this manual. DO NOT attempt to install this tank in any

other orientation. Doing so will result in improper tank operation

and property damage, and could result in serious personal injury

or death.

Part 5 - Piping

The design and installation of the solar water heating system should

be done by qualied individuals. It is important that good design

and installation practices be followed to assure that your system will

operate properly. Failure to follow installation guidelines for you solar

water heating system could cause component failure and possible

safety issues.

A. Potable Water Piping

It is very important that you do the potable piping before you pipe

into your solar system. Failure to do so may damage your water

heater.

Do not introduce HTF into any ttings on the heater except those

clearly marked for that purpose.

It is mandatory that all plumbing be done in accordance with local

and state codes or warranty will be void. It is also necessary to use

both thread tape and pipe dope on all mechanical connections. The

potable water piping is located on the side of your solar water heater

and marked Hot and Cold. It is recommended that unions or exible

copper connectors be used so heater can be easily serviced. Install a

shut-o valve on the cold feed near the solar water heater to isolate

the tank for future service.

Provide clear access to the storage tank, pump, expansion tank, mixing

valve, time clock and other key components. The components on the

potable side of the system may require future service or maintenance,

All drain back tanks eventually leak. Locate the tank where any

leakage from the relief valve, related piping, tank, or connections

will not result in damage to surrounding areas or lower oors

of the building. Any drain back tank should be installed in such

a manner that if it should leak the resulting ow of water will

not cause damage to the area in which it is installed. National

Plumbing codes require a drain pan for any water heater

installation. This drain pan should be sized with a maximum depth

of 2”, and a minimum diameter 2” greater than the diameter of

the water heater. The drain pan should empty into an open drain

line. This drain line should be 3/4” ID minimum, piped to an open

drain. Leakage damages ARE NOT covered by warranty. Failure to

install a drain pan is the sole responsibility of the owner and/or

installer. Reference UPC 2000 (Uniform Plumbing Code) Section

510 - Protection from Damage or IPC 200 (International Plumbing

code) Section 504 - Safety Devices. Leakage damages ARE NOT

covered by warranty.

In addition, water leak detection devices and automatic water

shuto valves are readily available at plumbing supply houses. IT

IS HIGHLY RECOMMENDED BY THE MANUFACTURER TO INSTALL

WATER LEAK DETECTION DEVICES AND AUTOMATIC SHUTOFF

VALVES IN ANY DRAIN BACK TANK INSTALLATION WHERE A

LEAKAGE OF WATER COULD RESULT IN PROPERTY DAMAGES.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

B. Water Chemistry Requirements

Chemical imbalance of the water supply may aect eciency and

cause severe damage to the appliance and associated equipment.

Water quality must be professionally analyzed to determine whether

it is necessary to treat the water. Various solutions are available to

adjust water quality. Adverse water quality will aect the reliability

of the system. In addition, operating temperatures above 135oF will

accelerate the build-up of lime scale and possibly shorten appliance

service life. Failure of an appliance due to lime scale build-up, low

pH, or other chemical imbalance IS NOT covered by the warranty.

The water must be potable, free of corrosive chemicals, sand, dirt,

and other contaminates. It is up to the installer to ensure the water

does not contain corrosive chemicals or elements that can damage

the heat exchanger. Potable water is dened as drinkable water

supplied from utility or well water in compliance with EPA secondary

maximum contaminant levels (40 CFR Part 143.3). If the water contains

contaminants higher than outlined by the EPA, water treatment is

recommended and additional, more frequent maintenance may be

required.

If you suspect that your water is contaminated in any way, discontinue

use of the appliance and contact an authorized technician or licensed

professional.

• Water pH between 6.5 and 8.5

• pH levels below 6.5 can cause an increase in the rate of

corrosion. pH of 8.5 or higher can potentially cause lime

scale build-up

• Maintain water pH between 6.5 and 8.5. Check with litmus

paper or have it chemically analyzed by a local water

treatment company.

• If the pH is not between 6.5 and 8.5, consult a local water

treatment company for solutions.

• Hardness less than 7 grains (120 mg/L) (Commercial Use -

water temperatures of 140oF and greater)

• Hardness levels above the required amounts can lead to lime

scale build-up throughout the system. Water below 5 grains/

gallon (85 mg/L) may be over softened.

• Consult local water treatment companies for unusually

hard water areas (above the required amounts) or for other

treatment solutions if water is being over softened (below 5

grains/gallon [85 mg/L]).

• Chloride concentration less than 100 ppm (mg/L)

• Do not ll appliance or operate with water containing

chlorides in excess of 100 ppm (mg/L).

• Using chlorinated fresh water should be acceptable as levels

are typically less than 5 ppm (mg/L).

• Do not connect the appliance to directly heat swimming

pool or spa water.

• Total Dissolved Solids (TDS) less than 500 ppm (mg/L)

• Total dissolved solids are minerals, salts, metals, and charged

particles that are dissolved in water.

C. Solar Heat Exchanger Piping

Set up the primary balance of the system components following the

piping detail in Figures 7 and 8.

Run ½” type M or larger copper pipes, or ex line sets, to and from

the collector following the direction of supports, penetrations, and

other relative items.

Copper or PEX may be used in the solar loop piping of drain back

systems.

When making a connection to the heat exchanger, use Teon Tape

and joint compound to prevent leaks. Do not apply heat directly to

the heat exchanger thread connection when sweating ttings.

Line pressure and temperature gauge shall be installed in the

collector supply and return lines to allow for a simple diagnostic

check of proper system operation. On a sunny day, the hot water

return line should be approximately 5 – 12oF warmer than the water

in the collector supply line. Compare the temperature readings in

the two line thermometers. The ¾” cold water supply line to the

storage tank must be insulated with a minimum 7/8” x ½” pipe

insulation to a minimum distance of 5’behind the storage tank, or to

the wall if closer than 5’.

D. Necessary Components for Water Heater Installation

Listed below are components needed for installation of the solar

water heater.

Solar Collector

Absorbs and transfers the sun’s energy into the solar heat exchanger

located on the bottom of the solar water heater.

Solar Air Release Vent*

This air vent allows air contained in the solar system to release.

*Remove and cap the solar air release vent after commissioning the

system.

Solar Collector Sensor

This sensor is wired to the solar controller and automatically turns

on the circulator pump when the dierential set point is reached

between the solar water heater and collector.

Solar Temperature and Pressure Gauge

The solar temperature and pressure gauge displays the actual

temperature and pressure supplied and returned to the solar

collector.

Check Valve

Helps minimize convective heat loss at night when the system is not

operating. If a check valve is not installed, most of the heater energy

stored during the day would be transferred into the collector and

lost.

Collector Isolation Valve (Valves #6 and 11)

Valves #6 and 11 isolate the collector loop from the solar water

heater.

Pressure Relief Valve (for Solar System)

Releases pressure in the solar loop when it exceeds 150psi. Contact

your installation contractor immediately if this valve opens and

releases uids.

so it is recommended that the connections be made with brass unions.

You must use copper and brass ttings in plumbing the solar storage

tank and expansion tank. The use of galvanized ttings, nipples,

dielectric unions, CPVC, PVC, or other plastic pipe is prohibited.

Hard copper connections to the city cold water supply line and home

hot water feed lines are recommended.

The gaskets in standard water heater ex hose connectors can become

brittle and compressed over time and begin leaking on the water

heater. If not detected in a timely manner, a drip or leak may cause

serious damage to the tank’s electrical components, or, in extreme

cases, cause the tank to leak from the outside in.

• The greater the amounts of TDS present, the higher the

corrosion potential due to increased conductivity in the

water.

• If using softened water to ll the appliance, it is still

possible to have high TDS. This water can be corrosive.

Consult local water treatment companies for other

treatment solutions to reduce this aect.

*NOTE: To promote appliance service life, it is strongly

recommended to follow the maintenance procedures in this

manual.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

System Fill Valve (Valve #8)

Fills the system with HTF. Also eliminates air from the system.

Expansion Tank

Precharged with air to allow for the expansion and contraction of

HTF.

Drain Valve (Valve #10)

Used to charge the collector loop with glycol, purge air from the

loop and drain the solar water heater heat exchanger of uid.

Collector Isolation Valve (for system ll) (Valve #11)

Used to direct the ow of HTF and to pressurize and eliminate air

from the solar system.

Ball Valve (for circulator) Valve #12

Used to isolate the circulator pump for service. Close both ball valves

to isolate pump.

Circulator (#13)

Circulates the HTF from the solar collector into the solar heat

exchanger.

Drain Valve (Tank) (Valve #14)

Flushes sediment which may accumulate on the bottom of the solar

water heater and also provides a means of draining the tank.

Tank Sensor

Is wired to the solar controller to measure the temperature on the

bottom of the solar water heater in conjunction with the solar

collector sensor. Turns the circulating pump on and o at the solar

control preset temperature dierentials.

Solar Controller

The solar controller turns the circulator on or o depending on heat

gained from solar operation. The controller also limits overheating

in the solar water heater. Some controllers have various options.

The controller should always be set in the “auto” position so that it

operates the array automatically when there is solar energy to be

collected.

Solar Heat Exchanger

The solar heat exchanger has an integral nned tube designed to

transfer heated energy rapidly from the solar collector into potable

water. The heat exchanger is constructed for superior corrosion

resistance and long-term reliability.

Hot Water Outlet

Each solar water heater has a hot water dip tube outlet which draws

water from the top of the heater. This helps to keep heat trapped

inside the highly insulated storage tank.

Solar Tank Temperature and Pressure Relief Valve

The relief valve must comply with standards for relief valves (ANSI

Z21.22) by a nationally recognized lab that maintains periodic

inspections of production listed equipment. No valve of any type

should be installed between the relief valve and tank. Local codes

govern installation of relief valves.

The relief valve outlet must be piped to a suitable open drain so that

the discharge water cannot contact live electric parts to eliminate

potential damage. Piping used should be approved for hot water

distribution. The discharge line must be no smaller than the outlet

of the relief valve and must pitch downward to allow complete

drainage. The end of the discharge piping should not be threaded

or concealed and must be protected from freezing. No valve of

any type, restriction or reducer coupling should be installed in the

discharge line.

Mixing Valve (Rated ASSE 1017) REQUIRED PER SRCC OG-300

Automatically blends hot and cold water feed lines to control

discharge to an acceptable and safe temperature. This also increases

the amount of hot water drawn from the solar water heater by

not allowing incoming cold water to fully temper the hot water

stored inside the tank. To help prevent injury due to scalding, it is

recommended that the mixing valve be set at 120oF.

Ball Valve (for cold water shut-o) (Valve #24)

The cold water shut o valve should be used in the event of an

emergency shutdown.

It is very important that you do the potable piping before you pipe

into the solar system. Failure to do so may damage your water heater.

Improper installation IS NOT covered by warranty.

Never use dielectric unions or galvanized steel ttings on any

domestic water connections or auxiliary connections. ONLY use

copper or brass ttings. Teon thread sealant must be used on all

connections.

E. Installation of the Drain Back Tank

1. Pipe solar collector return to the inlet tting located on the top

of the drain back tank.

2. Pipe drain back tank outlet (located near the bottom of the tank)

to the solar heat exchanger inlet.

3. Pipe solar heat exchanger outlet to the solar collector supply

tting.

(See installation diagrams in Part 5 for piping details.)

Insulate all hot water lines, as well as the nal 5’ of cold water supply

pipe leading to the system, with at least ¾”thick heat resistant rubber

tubing insulation.

Before commissioning the system, install the sight tube and an ASME/

ANSI rated 30 PSI pressure relief valve into the appropriate ttings on

the drain back tank using pipe dope. Follow further pressure relief

valve installation information listed below.

To avoid water damage or scalding due to relief valve operation:

• Discharge line must be connected to relief valve outlet and

run to a safe place of disposal. Terminate the discharge line

in a manner that will prevent possibility of severe burns or

property damage should the relief valve discharge.

• Discharge line must be as short as possible and the same

size as the valve discharge connection throughout its entire

length.

• Discharge line must pitch downward from the valve and

terminate at least 6” above the oor drain, making discharge

clearly visible.

• The discharge line shall terminate plain, not threaded, with

a material serviceable for temperatures of 375oF or greater.

• Do not pipe discharge to any location where freezing could

occur.

• No valve may be installed between the relief valve and heater

or in the discharge line. Do not plug or place any obstruction

in the discharge line.

• Test the operation of the relief valve after lling and

pressurizing the system by lifting the lever. Make sure the

valve discharges freely. If the valve fails to operate correctly,

immediately replace with a new, properly rated relief valve.

• Test relief valve at least once annually to ensure the waterway

is clear. If valve does not operate, turn the heater“o” and call

a plumber immediately.

• Take care whenever operating relief valve to avoid scalding

injury or property damage.

FAILURE TO COMPLY WITH THE ABOVE GUIDELINES COULD

RESULT IN FAILURE OF RELIEF VALVE OPERATION, RESULTING

IN POSSIBILITY OF SUBSTANTIAL PROPERTY DAMAGE, SEVERE

PERSONAL INJURY, OR DEATH.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

The circulating pump becomes very hot when running. Allow

sucient time to cool before touching. Failure to do so can lead to

personal injury.

F. Solar System Pump

Solar pumps must be installed at least 3’ below drain back tank level.

Remove integral check if so equipped. The solar system pump must

be sized to lift water to the top of the collector array. The solar pump

must be sized for proper ow and head loss. Friction losses must also

be considered when sizing a pump and solar system piping.

When sizing the pump, determine the head losses (also called psi, head

feet, and foot lift). Determine head loss through piping and the heat

exchanger using the solar collector manufacturer’s recommended

ow rates. Consider the vertical lift from the drain back tank to the

top of the solar panels. Size the pump for whichever is greater: Head

loss pumping through the system, or vertical lift, not both. A solar

modulating pump control is highly recommended on a drain back

system.

If the pump continues pumping at full speed rate after the system

is primed, the solar loop will often be over-pumped and the

recommended velocity will be exceeded. This condition will lead to

premature failure and reduced performance of the solar system.

G. Electrical Installation

ALL CONNECTIONS MUST BE MADE IN ACCORDANCE WITH LOCAL

ELECTRICAL CODES. A qualied electrician or contractor is required to

install a 115-120VAC duplex receptacle adjacent to the solar storage

tank. This receptacle is used to supply power to the pump/control

combo.

H. Installing the Drain Back Tank Sight Tube

IMPORTANT NOTE: A sight tube has been included with the solar

drain back tank. The sight tube allows service technicians, installers,

and users to quickly determine proper drain back system drainage and

solar system heat transfer uid level.

It is extremely important that this sight tube be installed BEFORE

lling the solar water heating system. Failure to install the sight tube

will result in a spillage of heat transfer uid, which, depending on

your system, may or may not contain antifreeze. Property damages

due to failure to install the sight tube ARE NOT covered by product

warranty.

1. Fit one (1) clamp on the solar drain back tank sight tube. Move the

clamp about two inches down the sight tube.

2. Fit the drain back tube onto the top sight tube tting. See Figure 5.

Figure 5 - Brass Drain Back Sight Tube Fitting

3. Move the clamp over the tube and onto the sight tube tting. This

will secure the tube to the tting. See Figure 6.

4. Fit one (1) clamp on the other end of the solar drain back tank sight

tube. Move the clamp about two inches down the sight tube.

Figure 6 - Sight Tube Secured to Brass Fitting

NOTE: If the tting was oset, use an adjustable wrench to straighten

it back up.

7. After the solar water heating system has been piped, check the

drain back sight tube and ttings and repair any leaks.

5. Fit the drain back sight tube onto the bottom sight tube tting. It

may be necessary to use an adjustable wrench to oset the tting.

This will ease securing the drain back tank sight tube to the tting.

6. Move the clamp over the tube and onto the sight tube tting. This

will secure the tube to the tting. See Figure 6.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

I. Applications

Figure 7 - Drain Back Tank without Heat Exchanger and Gas Fired Back Up

FIGURE NOTES:

1. This drawing is meant to demonstrate system piping concept only. The installer is responsible for all equipment and detailing by local codes.

2. Non-potable HTF shall only be used for the solar heat exchanger circuit. Never introduce non-potable HTF to any connection other than

the solar loop.

3. If there is a check valve on the cold water feed line, a thermal expansion tank suitable for potable water must be sized and installed within

this piping system between the check valve and cold water inlet of the solar water heater. The expansion tank should be properly sized for the

volume of stored hot water and maximum tank temperature. Normal solar control settings may be between 120oand 160o. Do not exceed

160oon the solar control setting.

4. A solar rated mixing valve is recommended if the domestic hot water setting is above 120oF. A standard mixing valve generally cannot

deliver the temperature protection range at which a solar system operates.

5. A minimum of 12 diameters of straight pipe must be installed upstream of all circulators.

6. Make sure solar storage tank is fully purged of air before power is turned on to the backup heat source.

7. Due to extreme temperatures, circulators with integral ow checks are not to be used in solar systems. If circulator comes equipped

with an integral ow check, remove it.

8. Non-vertical drain back solar system piping should pitch ¼”per foot back to the tank to facilitate draining.

9. No check valves are allowed in the solar loop.

10. Solar pumps must be installed 3’ below the drain back tank.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

Figure 8 - Drain Back Tank without Heat Exchanger and Electric Back Up

FIGURE NOTES:

1. This drawing is meant to demonstrate system piping concept only. The installer is responsible for all equipment and detailing by local codes.

2. Non-potable HTF shall only be used for the solar heat exchanger circuit. Never introduce non-potable HTF to any connection other than

the solar loop.

3. If there is a check valve on the cold water feed line, a thermal expansion tank suitable for potable water must be sized and installed within

this piping system between the check valve and cold water inlet of the solar water heater. The expansion tank should be properly sized for the

volume of stored hot water and maximum tank temperature. Normal solar control settings may be between 120oand 160o. Do not exceed

160oon the solar control setting.

4. A solar rated mixing valve is recommended if the domestic hot water setting is above 120oF. A standard mixing valve generally cannot

deliver the temperature protection range at which a solar system operates.

5. A minimum of 12 diameters of straight pipe must be installed upstream of all circulators.

6. Make sure solar storage tank is fully purged of air before power is turned on to the backup heat source.

7. Due to extreme temperatures, circulators with integral ow checks are not to be used in solar systems. If circulator comes equipped

with an integral ow check, remove it.

8. Non-vertical drain back solar system piping should pitch ¼”per foot back to the tank to facilitate draining.

9. No check valves are allowed in the solar loop.

10. Solar pumps must be installed 3’ below the drain back tank.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

Part 6 - Fluid Quality

A. Solar Loop Fluid Quality

HTP, Inc. recommends the use of potable water as HTF in its drain

back solar systems.

Fluid in direct ow through the solar collectors must rst meet

potable water requirements; any uid circulated through the

collectors should be non-corrosive to copper. In addition, water

quality must meet the following requirements listed below.

Total Dissolved Solids < 500 ppm

Total Hardness < 7 grains (120 ppm)

Chloride < 100 ppm

pH Levels 6.5 - 8.5

In order to meet health and safety regulations, solar system antifreeze

uid should be food grade polypropylene glycol, FDA rated as

“generally recognized as safe” (GRAS). Using proper concentrations

of glycol, solar systems can be operated at ambient temperatures as

low as -60oF. Freeze tolerance limits are based upon an assumed set

of environmental conditions. Refer to the DOWFROST specication

sheet in the back of this manual for recommended concentrations.

If using a glycol / potable water mix, the water must meet the

above requirements, and the glycol content of the liquid must

not exceed 50%, unless the manufacture species that a dierent

ratio is recommended for use with solar water heaters. Glycol may

need to be changed periodically (every 3-5 years) to prevent it from

becoming acidic; please refer to the guidelines provided by the

glycol manufacturer regarding replacement.

B. Fluid Safety Labeling

Included with your solar system is a set of labels which describe

component function. These labels alert the owner to potential

hazards. Ax these labels by string/wire/tie on valves, and/or “peel

and stick” on pipe insulation. Labels on the solar loop system must

contain the following warning:

“No other uid shall be used that would change the original

classication of the system. Unauthorized alterations to this system

could result in a hazardous health condition.” All labeling MUST be

in place at nal inspection.

C. Freeze Protection

Though drain back systems provide freeze protection for the solar

collectors, additional care must be taken in regions that experience

freezing conditions at any time throughout the year.

“Freeze tolerance limits are based upon an assumed set of

environmental conditions. Extended periods of cold weather,

including ambient air temperatures above the specied limit, may

cause freezing in exposed parts of the system. It is the owner’s

responsibility to protect the system in accordance with the Supplier’s

instructions if the air temperature is expected to approach the

specied freeze tolerance limit.”

For areas with temperatures not falling below –5oC/23oF, a simple

low temperature controller may be used to guard against freezing. If

necessary, backup freeze protection in the form of an uninterrupted

power supply (UPS), or freeze valves (which open to allow water to

dribble out) should also be installed.

For areas with temperatures that fall below –5oC /23oF, a closed

loop lled with a polypropylene glycol-water mix should be used to

provide hard freeze protection. Please refer to glycol manufacturer’s

specications about the temperature ranges the liquid can

withstand. Only food grade polypropylene-glycol, FDA rated as

GRAS, should be used.

NOTE: HTP DOES NOT WARRANT THE SOLAR WATER HEATER, SOLAR

COLLECTOR, OR ANY COMPONENTS AGAINST FREEZE RELATED

DAMAGE.

Part 7 - Start-Up Preparation

DO NOT MOVE ON TO THESE STEPS UNTIL THE ENTIRE SOLAR

SYSTEM, INCLUDING ALL PIPING, SOLAR COLLECTORS, SENSORS,

PUMP, CONTROLS, AND ELECTRICAL CONNECTIONS, ARE PROPERLY

SECURED, INSULATED, LABELED AND INSTALLED.

A. Check for Leaks in the Solar Loop

To check for leaks in the solar loop, utilize the same procedure used by

plumbers checking for leaks in new construction.

1. Isolate the solar loop.

2. Use a compressor to pressurize the solar loop to 25 PSI.

3. After 1 hour, check to see if there has been a drop in pressure.

a. If pressure has not dropped, slowly release the remaining air

pressure in the loop and move on to Section B.

b. If pressure has dropped, use a spray bottle with soapy water

to locate the leak. Once all leaks have been found and repaired,

pressurize the solar loop again.

NOTE: Do not introduce heat transfer uid into the solar system until

you have successfully completed the pressure test.

B. Fill the Drain Back Reservoir

1. Attach hose to solar loop ll valve.

2. Open ll valve and the bleed valve on the drain back tank sight

tube (see Specication drawings for locations).

3. Slowly ll the drain back reservoir to the top of the sight tube.

4. When nearly full, close bleed valve and add between 2 and

5 PSI head pressure to the system. When system is full and at

desired head pressure, shut o ll valve.

5. Remove ll hose.

Take care not to overll the drain back solar system. Overlling will

cause a potentially dangerous condition that could lead to freezing

and failure of the solar system.

C. Start-Up Procedure

Once the system is lled as prescribed above:

1. Apply power to the solar controller.

2. Set controller to operate pump manually. Let pump run for 5

minutes.

3. Check for leaks at collectors and in attic, if applicable.

4. If no leaks are found, program controller for your drain back

system (see solar controller programming instructions).

If the sun is shining and the tank is cool, the pump should turn on

and begin circulating water. Check control settings to maximize your

system performance.

Part 8 - Service / Maintenance Procedures

A properly maintained solar water heating system can provide years

of dependable, trouble-free service. It is suggested that a routine

preventive maintenance program be established and followed by the

end user with the solar contractor. Listed below is the maintenance

check list that outlines the primary components of the solar system

that need to be inspected annually.

1. HTF Glycol (if used) – It is very important that the quality of the

glycol is maintained to avoid damage to the collector loop and related

components. See the manufacturer’s data sheet for further details.

2. Water quality can aect the operation of the solar heat exchanger

over time. In very hard water areas, it is recommended to drain (#14) a

few gallons of water from the bottom of the storage tank to keep the

water heater free of sediment.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

A. Shutdown Procedures

Simply unplug the solar controller to shut down the drain back system.

The pump will stop and water will drain out of the collectors into the

reservoir.

E. Estimated Life of Components

Proper care and maintenance will determine the life expectancy of the

individual components of the solar system. Refer to manufacturer’s

warranty information to determine coverage of individual

components. To obtain warranty service, call your local service or

installing contractor.

Never open the pressure relief valve while the system is in operation

or hot water is present. Allow to cool prior to opening. Failure to do

so could result in serious personal injury or death.

6.The area near the water heater must be kept free of ammable liquids

such as gasoline, paint thinners, adhesives, or other combustible

materials.

F. Temperature and Pressure Relief Valve

A temperature and pressure relief (T&P) valve is designed for

emergency safety relief and shall not be used as an operating control. A

T&P valve functions by discharging water in an emergency. Therefore,

it is essential that a discharge line be piped from the valve in order to

carry the overow to a safe place of disposal. The discharge line must

be the same size as the valve outlet, must pitch downward from the

valve, and terminate at least 6” above a drain where any discharge will

Never open the pressure relief valve while the system is in operation

or hot water is present. Allow to cool prior to opening.

B. Draining the Drain Back Reservoir

1. Unplug the controller and wait until all water returns to the

reservoir.

2. Attach hose to ll valve.

3. Open the pressure relief valve.

4. Open ll valve.

5. Allow the system to completely drain.

6. Close ll valve and the pressure relief valve.

7. Remove drain hose.

D. Vacation Shutdown Procedure

If hot water is not to be used for an extended period of time, unplug

the controller and allow the solar collectors and piping to drain into

the drain back reservoir. To re-energize, simply plug in the controller.

C. Routine Maintenance

The heat transfer uid level in the drain back reservoir should be

checked twice a year. With the system turned o, make sure that the

water level in the reservoir reaches the top of the sight tube. If not,

follow the instructions in “Fill the Drain Back Reservoir”, this manual.

Periodically check the temperature dierence between the collector

supply (from the tank to the collector) and collector return lines (from

the collector to the tank). As a rule, an 8 – 12° temperature gain should

be expected across a collector, in bright sun, at the proper ow rate.

Larger systems may have a greater temperature dierence.

The storage tank should be ushed to prevent scale build up

on an annual or bi-annual basis following the manufacturer’s

recommendations.

Following installation of the T&P Relief Valve, the valve lever

MUST be operated AT LEAST ONCE A YEAR by the water heater

owner to ensure that waterways are clear. Certain naturally

occurring mineral deposits may adhere to the valve, blocking

waterways and rendering the valve inoperative. When the lever

is operated, hot water will discharge if the waterways are clear.

PRECAUTIONS MUST BE TAKEN TO AVOID PERSONAL INJURY

FROM CONTACT WITH HOT WATER AND TO AVOID PROPERTY

DAMAGE. BEFORE operating lever, check to see that a discharge

line is connected to the valve, directing the ow of hot water from

the valve to a proper place of disposal. If no water ows when the

lever is operated, replacement of the valve is required. TURN THE

WATER HEATER “OFF” AND CALL A PLUMBER IMMEDIATELY.

Part 9 - Troubleshooting

Owners are advised to contact the installer whenever in-depth

interaction with the solar system is required.

A. Leaks

For leaks in the potable water system or solar storage tank, close the

cold water inlet and unplug the solar controller. This will isolate the

solar system until repairs can be made.

3. Clean and inspect the solar collector (#1). Dirt or lm may settle

on the surface and aect performance. Check collector supplier for

cleaning procedures.

4. Check piping and component insulation for deterioration.

5. Inspect the T&P valve (#19) on the water heater. Lift the release

handle lever. Make sure discharge is directed to an open drain.

be clearly visible.

For your safety, DO NOT attempt repair of electrical wiring or other

operating controls. Refer repairs to qualied service personnel.

Failure to do so could result in serious personal injury or death.

C. Operating Suggestions for the User

A properly designed solar hot water system provides solar energy

for approximately 70 – 90% of annual hot water needs. Listed below

are some suggestions that will maximize the benets of your solar

hot water system.

1. Showers - If possible, take showers during the day, or in the

early evening. Use low ow showerheads to reduce water

consumption.

2. Dishwashing – Run your dishwasher during the day, after

showers, to ensure as much hot water as possible is available

for showers.

3. Laundry – Spread clothes washing over the week instead of

washing all at the same time.

4. Single Lever Faucets – When using cold water, make sure the

lever is all the way over in the cold position. This prevents

hot water from inadvertently owing from the solar storage

tank.

B. Other Problems

A noisy pump could be an indication of worn bearings, obstructions,

or a leak in your system. Call your installer for diagnosis of the

problem, repair of the system, and/or replacement of components.

lp-585 Rev. 000 Rel. 001 Date 9.10.18

Problem Reason Remedy

No Hot Water

1. Improper Wiring Rewire per Wiring Diagram

2. No Power - Blown Fuse or Tripped Circuit Breaker

a. Shorted Wiring

b. Circuit Overloaded

c. Improper Wiring

a. **Replace or repair

b. **Provide adequate circuit or reduce load

c. ** Rewire per diagram

3. Solar System Incorrectly Installed **Check installation

4. Leaking Plumbing or Open Hot Water Faucet(s) **Ensure all faucet(s) are closed. Check water meter

Not Enough Hot

Water

1. Heater Undersized Reduce rate of hot water use

2. Wired Incorrectly **Check wiring or replace

3. Solar System Incorrectly Installed **Check installation

Water Too Hot or Not

Hot Enough

1. Thermostat Setting Too High or Low Change setting as required

2. Thermostat Out of Calibration **Replace

3. Solar System Incorrectly Installed **Check installation

Table 5 - Troubleshooting - See Solar Water Heater Installation Manual for More Detailed Maintenance Information - ** USER - For your safety, DO

NOT attempt repair of electrical wiring, thermostat, or operating controls. Refer repairs to qualied service personnel.

The risk of scald injury increases as you increase water

temperature. Use a water tempering or mixing valve and extreme

caution when using hot water to avoid scald injury. Consult codes

for conformance. Failure to follow the instructions in this warning

statement could result in serious personal injury or death from

scalds.

Be sure to disconnect electrical power before performing service.

Failure to do so could result in electrical shock, property damage,

serious personal injury, or death.

If draining of the water heater is necessary, open the T&P valve or

a hot water tap to prevent vacuum buildup in the tank and piping.

Part 10 - System Parts Listing

A. Estimated Component Life

These water storage tanks are designed for 12 – 20 years of use.

When installed and maintained as directed by this manual, one can

expect many years of trouble-free service from this solar system.

However, all components in this system are subject to installation

conditions. For example: Where hard water is present, mineral

deposits can shorten the life of components. Periodic maintenance

as prescribed by this manual ensures that these components are

well protected from such damage.

B. Warranties and Disclaimers

NOTE: WE EXCLUDE ANY WARRANTY FOR, OR LIABILITY FROM ACTS

OF NATURE, INCLUDING FREEZE DAMAGE.

Warranty periods for tank components are listed in the table below:

Manufacturer Item Model # Tank

Coverage

Component

Coverage

HTP, Inc.

Drain

Back

Tank

SSU-10DB 5 (Five)

Years 1 (One) Year

Table 6 - Warranty Periods

Figure 9 - Drain Back Tank Replacement Parts

lp-585 Rev. 000 Rel. 001 Date 9.10.18

VISCOSITY: The HTF viscosity over the service temperature range is

based on a specic gravity 15/15oC (60/60oF) 1.053-1.063. DOWFROST

inhibited glycol-based uid has an eective operating temperature

range of -50oF to 250oF. At temperatures below -50oF, increased

viscosity (>1,000 centipoise) can make use of DOWFROST impractical

unless larger pumps are installed. At the upper end of the operating

range for DOWFROST uid, a maximum bulk temperature of 250oF is

recommended. Film temperature should not exceed 300oF. DOWFROST

uid can tolerate brief temperature excursions up to 100oF above the

maximum recommended temperatures. However, extended exposure

of the uid to temperatures in excess of 50oF above the maximum

recommended temperatures will result in accelerated degradation

of the glycol and inhibitor systems. In addition, the lm temperature

should remain within 50oF of the bulk uid temperature and the

pressure at all points in the system should be at least 5 psi greater than

the vapor pressure exerted by the uid to avoid localized boiling and

resulting precipitation. At temperatures above 150oF, the system must

be closed to avoid rapid oxidation of the propylene glycol, inhibitor

depletion, and subsequent increased corrosion. Automatic make-

up water systems should be avoided in order to prevent undetected

dilution or loss of glycol and consequent loss of freeze and corrosion

protection.

FLAMMABILITY: When mixed with water, DOWFROST is not

ammable, as the uid has no measurable ash point (Pensky-Martens

Closed Cup) in concentrations up to 80% glycol. Undiluted DOWFROST

has a ash point of 214oF (Pensky-Martens Closed Cup). It is possible

to ignite solutions of propylene if enough water has been vaporized

and the concentration of propylene glycol increases to greater than

80 percent.

INSPECTION AND TREATMENT OF HEAT TRANSFER FLUID: You

can quickly determine the condition of your uid by examining its

appearance and odor. Any drastic variation from the initial uid

specications, such as a black or dark-grey color, presence of an oily

layer, burnt odor, or any heavy sludge in the uid may indicate the

need for replacement.

TESTING THE FLUID pH LEVEL: Control of pH between 8 and 10 is

important to minimize corrosion and glycol degradation. Using narrow

range pH paper, such as pHydrion Control paper with a 7.2 to 8.8 pH

range, is an easy and reliable way to read your pH level. A pH tester

can also measure alkalinity or acidity and give you an indication of the

reserve alkalinity or inhibitor level of the uid. The desirable pH range

should fall between 8.0 and 10.0. Adjustments can be made using a

50% solution of sodium hydroxide or potassium hydroxide if the pH is

approaching the acidic range (below 8.0). An inexpensive pH tester is

available from Misco Products. The accuracy of this product is +/- 0.5

pH. Contact Misco Products at 1-800-358-1100 and ask for the Dow

discount.

SPILL, LEAK, AND DISPOSAL PROCEDURES: Using appropriate safety

equipment, small spills may be soaked up with common absorbent

material. For large spills, the uid should be pumped into suitable

containers located in diked areas. Residual material should be cleaned

up with water. Concentrate can be handled according to local, state,

and federal regulations.

EMERGENCY OVERVIEW

POTENTIAL HEALTH EFFECTS

EYE: May cause slight transient (temporary) eye irritation.

Corneal injury is unlikely. Mists may cause eye irritation.

FIRST AID: FLUSH EYES WITH PLENTY OF WATER

SKIN CONTACT: Prolonged contact is essentially non-irritating to skin.

A single prolonged exposure is not likely to result in the material being

absorbed through the skin in harmful amounts. Repeated exposure

may cause aking and softening of skin.

FIRST AID: WASH OFF IN FLOWING WATER OR SHOWER

INGESTION: Single dose oral toxicity is considered to be extremely

low. No hazards anticipated from swallowing small amounts

incidental to normal handling operations.

FIRST AID: NONE REQUIRED

INHALATION: At room temperature, vapors are minimal due to

physical properties. Mists may cause irritation of upper respiratory

tract (nose and throat).

FIRST AID: REMOVE TO FRESH AIR.

IF EFFECTS OCCUR, CONSULT A PHYSICIAN.

NOTE TO PHYSICIAN: NO SPECIFIC ANTIDOTE.

SUPPORTIVE CARE. TREATMENT BASED ON

JUDGEMENT OF THE PHYSICIAN IN RESPONSE TO

THE REACTION OF THE PATIENT. CONSULT DOW CHEMICAL

24 HOUR EMERGENCY 1-989-636-4400

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