SunEarth CASCADE DRAINBACK Instruction manual

™

CASCADE DRAINBACK™
DOMESTIC SOLAR WATER
HEATING SYSTEM
INSTALLATION, OPERATION AND MAINTENANCE MANUAL
The Cascade Drainback solar water heating system has gone through an extensive design, technical and per-
formance review by the Solar Rating & Certification Corporation (SRCC). The installation of your Cascade
Drainback system is intended to be executed by properly licensed and experienced professional contractors
in accordance with SRCC Standard OG-300, “Operating Guidelines and Minimum Standards For Certifying
Solar Water Heating”, and must conform to applicable federal, state and local regulations, codes, ordinances
and standards governing the installation of solar water heating systems.
The solar energy system described by this manual, when properly installed and maintained, meets the minimum
standards established by the SRCC. This certification does not imply endorsement or warranty of this product
by the SRCC.
OG-300 system certification is granted to SunEarth by the SRCC. It may not be used for any commercial pur-
pose without the prior written consent of SunEarth. SunEarth must approve any deviation from the specified
materials and methods described in this manual in writing.
The Cascade Drainback solar water heating systems can be protected against freeze damage to temperatures as
low as -50ºF (-46ºC). This system should not be installed in areas within the continental United States where
the annual ambient temperature has ever fallen below minus 50° Fahrenheit (-46° Celsius). The Cascade
Drainback system must be installed as specified in this manual to have effective freeze protection at these low
temperatures.
Freeze tolerance limits are based upon an assumed set of environmental conditions. Extended periods of cold
weather, including ambient air temperatures above the specified limit, may cause freezing in exposed parts of
the system. It is the owner’s responsibility to protect the system in accordance with SunEarth’s instructions if
the ambient air temperature approaches the specified freeze tolerance limit.

Installation Manual
TABLE OF CONTENTS
Safety Information............................................................................................................................1
Preface................................................................................................................................................3
1) Introduction ..................................................................................................................................3
2) System Description and Operational Principle .........................................................................3
3) Installation Requirements – General .........................................................................................5
4) Installation Requirements – Specific..........................................................................................5
5) System Start Up Procedures .....................................................................................................19
6) Two Modes of System Operation..............................................................................................19
7) Isolating the Major Components and Shut Down Procedures..............................................20
8) Summer Vacation Procedures...................................................................................................20
9) Maintenance and Troubleshooting ...........................................................................................20
10) Cascade Drainback System Component Parts......................................................................22
11) Estimated Component Life Expectancy.................................................................................23
12) System Operating Parameters ................................................................................................23
Appendix A. OG-300 Approved Primary Components..............................................................24
Appendix B. Pump Sizing Tables..................................................................................................27
Appendix C. SRCC OG-300 Certified System Model Numbers................................................29
Appendix D. Cascade Drainback OG-300 Labels .......................................................................30
Appendix E. SunEarth Collector Warranty Statement..............................................................32

P.1
Time/Temperature Relationship in Scalds
Temperature Time To Produce a Serious Burn
120°F More than 5 minutes
125°F 1½ to 2 minutes
130°F About 30 seconds
135°F About 10 seconds
140°F Less than 5 seconds
145°F Less than 3 seconds
150°F About 1½ seconds
155°F About 1 second
Table courtesy of Shriners Burn Institute
The chart shown above may be used as a guide
in determining the proper water temperature for your home.
!
DANGER: Households with small children, disabled,
or elderly persons may require a 120°F or lower thermostat
setting to prevent contact with “HOT” water.
NOTICE: Mixing valves should be installed to reduce the
point of use water temperature by mixing hot and cold water
in branch water lines. Contact a licensed installer or the local
plumbing authority for further information.
The temperature of the water in the water heater can be regu-
lated by setting the temperature dial of the adjustable surface
mounted thermostat locatedbehindthe jacket access panel.
This thermostat controls the
water heater’s heating ele-
ment only. (A separate ther-
mostat should be utilized in
monitoring the temperature
from the collector).
To comply with safety reg-
ulations the thermostat is
factory set at 120° F or less
where local codes require.
!
DANGER: Hotter water increases the potential for Hot
Water SCALDS.
°
!
DANGER!
WATERTEMPERATURE SETTING
Safety and energy conservation are factors to be considered when selecting the water
temperature setting of water heater’s thermostat. Water temperatures above 125°F
can cause severe burns or death from scalding. Be sure to read and follow the warnings
outlined on the label pictured below.
!
DANGER: Burns from Hot Water and
Steam - Use extreme care when opening relief
valves, charging closed loop, and filling storage
tank.
The electrical element booster thermostat has
been factory set at 50°C (120°F) to reduce the
risk of scald injury. Adjusting the thermostat to a
higher setting is not recommended. Hotter water
increases the potential for Hot Water Scalds.
R
E
S
E
T
R
E
S
E
T
TURN OFF
PO WER
BEFORE
SE RV I CING
90°F150°F
125°F
(66°C)
(52°C)
(32°C)
Reset button
Thermostat
protective
cover
Thermostat
dial pointer
IMPORTANT SAFETY INFORMATION.
READ ALL INSTRUCTIONS BEFORE USING.

P.2
!
WARNING!
For your safety, the information in this manual must be followed to minimize the risk
of fire or explosion, electric shock, or to prevent property damage, personal injury, or loss
of life.
FOR INSTALLATIONS IN THE STATE OF CALIFORNIA
California Law requires that residential water heaters must be braced, anchored or
strapped to resist falling or horizontal displacement due to earthquake motions. For
residential water heaters up to 52 gallon capacity, a brochure with generic earthquake
bracing instructions can be obtained from: Office of the State Architect, 1102 Q Street,
Suite 5100, Sacramento, CA 95814 or you may call 916-445-8100 or ask a water heater
dealer.
However, applicable local codes shall govern installation. For residential water heaters
of a capacity greater than 52 gallons, consult the local building jurisdiction for acceptable
bracing procedures.
Have the installer show you the location of the circuit breaker and how to shut it off if
necessary. Turn off the circuit breaker if the water heater has been subjected to overheating,
fire, flood, physical damage or if the ECO fails to shut off.
Read this manual entirely before installing
or operating the water heater.
Be sure your appliance is properly installed
in accordance with local codes and the
provided installation instructions.
SAFETY PRECAUTIONS
Use this appliance only for its intended
purpose as described in this Installation,
Operations and Maintenance Manual
Be sure to read and understand the entire Installation, Operation and Maintenance
Manual before attempting to install or operate this water heater. It may save you time
and cost. Pay particular attention to the Safety Instructions. Failure to follow these
warnings could result in serious bodily injury or death. Should you have problems
understanding the instructions in this manual, or have any questions, STOP, and get
help from a qualified service technician, or the local utility.
Do not attempt to repair or replace any part
of your water heater unless it is specifically
recommended in this manual. All other
servicing should be referred to your install-
ing contractor or local SunEarth Distributor.
IMPORTANT SAFETY INFORMATION.
READ ALL INSTRUCTIONS BEFORE USING.
READ AND FOLLOW THIS SAFETY INFORMATION
CAREFULLY.
SAVE THESE INSTRUCTIONS

PREFACE
Let us first offer two words of grateful appreciation.
Thank You! We sincerely appreciate your business.
SunEarth also wishes to say thank you for “going
solar”. Solar water heating systems reduce our
nation’s dependence on polluting fossil fuels, mini-
mize the greenhouse gas emissions associated with
conventional water heating and, very importantly,
lower your monthly utility costs.
Established in 1978, SunEarth is a leading U.S.
solar equipment manufacturer. Our products
include industry standard Empire, SunBelt, Imperial
and ThermoRay solar water heating collectors,
CopperHeart integral collector storage systems,
SunSiphon packaged thermosiphon systems,
SunBurst all copper absorber plates, Solar Strut
and “RexRack” mounting systems. We also build
specialty collectors for unique architectural and
building applications. SunEarth Solar Rating and
Certification Corporation (SRCC) Standard OG-300
certified solar water heating systems are sold by
leading solar, plumbing and building contractors
throughout the United States.
Your Cascade Drainback solar water heating system
has been designed to meet exacting SRCC OG-300
certification requirements. The specific components
found in your system have been selected by your
installation contractor for their proven reliability,
longevity and performance in your specific region
of the country.
SunEarth maintains a policy of continuous review
and improvement to ensure that Solaray systems
incorporate any appropriate technological advances.
To ensure that products represent the current state
of the art in solar water heating SunEarth systems
are subject to change without notice. Please consult
the SunEarth Inc. website at www.sunearthinc.com
for current information and latest manual revisions.
1) INTRODUCTION
Solar water heating systems are climate and site
specific appliances. Different types of solar sys-
tems are installed around the world in accordance
with regional weather and water quality conditions.
System performance varies as a function of the
household hot water load, including daily showers,
laundry and kitchen uses, the average ground water
and ambient air temperatures, the home’s roof pitch
and orientation, and, of course, the seasonal intensi-
ty of solar radiation. These variables, some of which
change from home to home on the same neighbor-
hood street, will determine how much energy and
money your Cascade Drainback system will save on
an annual basis.
Your Cascade Drainback solar system is known as
a “forced circulation closed loop drainback” system
because it utilizes a mechanical pump to efficiently
circulate water throughout the unpressurized closed
loop solar piping. The “drainback” connotation
refers to the freeze-protection mechanism used in
the system. In drainback systems, the heat exchange
fluid (water) in the collector array and solar loop
piping drains back by gravity into the drainback
storage reservoir when the pump stops circulating.
Air replaces water in the collector array and solar
loop piping to prevent it from freezing when the
pump is off.
This manual is intended as a basic “solar water heat-
ing primer”. Our goal is to familiarize you with the
proper installation, operation, and maintenance of
your Cascade Drainback solar system. This system
is required to be installed by properly licensed solar
or plumbing contractors in accordance with SRCC
Standard OG-300 and all applicable national, state
and local codes, ordinances and regulations govern-
ing solar installations as well as good trade prac-
tices. Failure to follow the procedures and practices
described in this manual may void manufacturer
warranties for specific component parts.
This manual covers installations utilizing one or two
SunEarth solar collectors with a single solar storage
tank and also two tank systems that include a solar
storage tank and supplemental tank type or tankless
water heater. For simplicity, the singular form will
be used throughout this manual when referring to
the system components and permutations. Frequent
reference will be made throughout this manual to
specific component parts. The placement of each
component in the system is found in Figures 17, 18
and 19. An explanation of the component function
is found in pages 23-24.
2) SYSTEM DESCRIPTION AND
OPERATIONAL PRINCIPLE
The key components in the Cascade Drainback solar
water heating system include the SunEarth solar col-
lector, drainback reservoir, solar storage tank with
integral heat exchanger, circulation pump, differen-
tial temperature controller and mixing valve.
P.3

The SunEarth solar collector is the heart of the
Cascade Drainback system. Simply stated, when the
sun is shining, heat energy is absorbed by the solar
collector’s all copper absorber plate and transferred
to the water circulating through the solar collector.
The system pump efficiently circulates this heated
water through the collector piping and integral tank
heat exchanger. As the water passes through the
heat exchanger, the heat in the fluid is transferred to
the potable water in your solar storage tank. As this
process is repeated during the average sunny day,
the temperature in your solar storage tank rises.
The differential temperature controller is the brain
of the system. The controller uses temperature sen-
sors to constantly monitor the temperatures at the
collector and at the tank. The controller automati-
cally turns the pump on when useful heat is avail-
able at the collector and turns the pump off when
there is insufficient solar heat available or the tank
has reached maximum temperature.
Depending upon the system demand, time of year
and the weather, the circulating pump may either
run intermittently throughout the day or constantly
for hours at a time.
Both single and double tank Cascade Drainback
systems are designed to accommodate two separate
modes of system operation. Your system can either
(1) serve as a preheater to your conventional electric
or gas water heater or (2) be bypassed entirely and
run 100% on utility power during inclement weather
or when maintenance is required. The installation of
an optional water heater time switch allows you to
control both the frequency and duration of supple-
mental electric resistance water heating.
Section 6 provides instruction in setting the system
for automatic operation in each of these two modes.
The water in the SunEarth collector and the solar
loop piping automatically drains back into the
drainback reservoir each time the circulating pump
turns off. Gravity drains the piping and provides
the freeze and overheat protection for your Cascade
Drainback system.
The system also can be manually drained in order to
protect the integrity of the collector and solar loop
piping if it is exposed to extended periods of disuse
or persistent hard freeze conditions below - 50°
Fahrenheit. (See Section 7 for instructions).
3) INSTALLATION REQUIREMENTS –
GENERAL
3.1 Permits:
The contractor shall obtain all required permits and
approvals.
3.2 Codes, Ordinances and Standards:
P.4
SYSTEM ORIENTATION
fig. 1

P.5
The installation shall conform to all federal, state
and local regulations, codes, ordinances and stan-
dards governing the installation of solar water heat-
ing systems. The contractor shall adhere to sound
building safety and trade practices. Special consid-
eration must be given to building code requirements
for roof loading and the penetration of structural
members and fire rated assemblies.
3.3 Shading Considerations:
The collectors must be located in an area of the roof
that will not be shaded for the majority of the day all
year round. Adjacent build¬ings and trees should
be checked for possible winter shading. The collec-
tor should not be shaded by any permanent obstacle
between 9:00 a.m. and 3:00 p.m. on any day of the
year. An instrument such as the Solar Pathfinder
can be used for solar site analysis.
3.4 Roof and Site Inspection:
Before the installation, the contractor shall inspect
the condition of the roof and notify the homeowner
of any existing roof damage or necessary repairs.
3.5 Structural Considerations:
The collectors must be located in a structurally
sound area of the roof. Penetrations into structural
members must not compromise the structural prop-
erties of the structural member.
ENSURE THAT ALL STRUCTURAL
MEMBER PENETRATIONS COMPLY WITH
APPLICABLE CODES.
The collector mounting method must be capable of
maintaining the required tilt and azimuth of the col-
lector under the expected dead loads, wind loads and
snow loads for the location.
3.6 Building Envelope:
Penetrations through the building envelope (includ-
ing roof, walls or floor penetrations) must not impair
the enclosure function and must meet applicable
codes and best practices.
Roof penetrations whether for structural mounts or
pipe penetrations must be sealed and leak proofed
as per applicable codes and National Roofing
Contractors Association practices.
Building penetrations must allow vermin intrusion.
3.7 Fire-Rated Assemblies:
Penetrations through fire-rated components must
not reduce the fire resistance of the assembly below
code.
3.8 Building Materials:
Building materials adjacent to solar components
must not be exposed to elevated temperatures.
3.9 Confirmation of Installation Site:
The homeowner and contractor shall confirm the
location of all roof and ground mounted components
in advance of the installation.
3.10 Fluid Identity and Toxicity:
The Cascade Drainback system uses water as a heat
transfer fluid, this is heated in the collector and
indirectly heats the domestic hot water through the
integral heat exchanger in the solar tank. Use of
toxic heat transfer fluids is prohibited.
3.11 Maintenance and Servicing
When installing the system, make sure that all the
components all the components are accessible and
easy to reach. Provide for clear access to the storage
tank, pump, drainback reservoir, mixing valve and
other key components. If a component in the potable
water side of the system may require future service
or maintenance make the connections with brass
unions or other approved connections.
4) INSTALLATION
REQUIREMENTS – SPECIFIC
4.1 Collector Orientation
The performance of solar water heating systems in
the Northern Hemisphere is optimized when the col-
lector is mounted facing True South. Performance,
however, suffers very little when the collector is ori-
ented no more than 45° East or West of True South.
The collector should be unshaded by any permanent
obstacle between 9:00 a.m. and 3:00 p.m. on any
day of the year.
4.2 Collector Tilt
Optimal annual efficiency is achieved by tilting the
solar collector at an angle that equals your latitude
plus an additional 10°. This tilt angle favors the
lower winter sun when collector performance is at
its lowest and minimizes overheating during the hot-
P.5

test summer months.
To ensure proper water drainage from the glazing
of the collector, the collector must be sloped from
horizontal. Never mount the collector parallel to a
flat roof. Use SunEarth RexRack, Landscape rack
or Universal tilt products to tilt the collector to the
proper angle
The minimum acceptable tilt angle from horizontal
is 15°.
4.3 Basic Mounting Procedures
The SunEarth solar collector in your Cascade
Drainback solar system should be mounted in a
vertical orientation parallel to the slope of the roof
if possible. This orientation allows the internal riser
tubes to rapidly drain when the circulation pump
shuts off.
CRITICAL: BOTH THE COLLECTORS
AND THE SOLAR LOOP PIPING MUST BE
SLOPED TO DRAIN AWAY FROM THE
HIGHEST POINT IN THE SYSTEM BACK
TO THE DRAINBACK RESERVOIR.
The minimum required slope is 1/4” vertical drop
per foot of horizontal piping run (2% minimum
slope). Use the steepest slope possible on the return
line piping to the drainback reservoir. Water will
drain down both the return tubes directly to the
drainback reservoir and the supply tubes by spin-
ning the pump impeller in the reverse direction.
The collector should be mounted as close to the stor-
age tank as possible to minimize heat loss in the pip-
ing runs. The solar collector should be mounted on
the roof in accordance with these general principles:
4.3.1 The most important structural consideration
is to securely anchor the solar collector and the
SunEarth mounting hardware to the structural mem-
bers of the roof with stainless steel hanger bolts,
lag bolts, standoff mounts or other approved roof
attachment method. The solar collector shall be
attached to the mounting hardware as detailed in
Figures 2 – 4. (Note: The drawings in this manual
detail mounting hardware for the SunEarth Empire,
Imperial, SunBelt and ThermoRay series collectors).
4.3.2 The collector should be raised from the roof
surface to allow for rainwater and debris to pass
P.6
COLLECTOR
C-SSN
STAND OFF
FLASHING
STAINLESS LAG BOLT
fig. 2
STAND OFF ON BARREL TILE ROOF

P.7
P.7
COLLECTOR
C-SSN
STAND OFF
FLASHING
STAINLESS LAG BOLT
fig. 3
STAND OFF ON FLAT TILE ROOF
COLLECTOR
C-SSN
FOOT MOUNT
FLASHING
STAINLESS LAG BOL
fig. 4
STRUT ON FOOT MOUNT FOR COMPOSITION ROOF

under the collectors and for proper ventilation of
the roofing material. There should be at least 1 ½”
of clearance between the roof surface and the bot-
tom of the solar collectors. Local codes may require
greater clearance for snow shedding, etc.
4.3.3 When selecting mounting hardware and fas-
teners it is extremely important to avoid galvanic
corrosion resulting from the direct contact of incom-
patible metals. Use of SunEarth anodized aluminum
Solar Strut mounting hardware and stainless steel
lag or hanger bolts, and fastening hardware is rec-
ommended. In climates subject to severe winters
or high humidity use of galvanized fasteners is
prohibited.
4.3.4 Preserving the integrity of the roof membrane
is the most important roofing consideration. Ensure
that all roof penetrations required to plumb and
mount the solar collector are properly flashed and
sealed in accordance with best roofing practices.
4.3.5 If the region is subject to hurricane condi-
tions, additional steps may be required to secure
the collector and mounting hardware to the struc-
tural members. In certain areas of the country, local
building codes may require collector wind load
testing or prescribe specific mounting procedures.
Consult your local building department.
4.4 Collector Loop Plumbing
The collector loop must be plumbed using copper
or stainless steel piping and copper, brass, bronze
or stainless steel fittings. Lead-free solder shall be
used. Use of galvanized steel, CPVC or PVC is pro-
hibited. PEX may be used only in systems that meet
the following conditions:
•The PEX tubing shall not be exposed to sunlight.
•Water must be used as the heat transfer fluid.
•The system shall be non-pressurized (capped at
atmospheric on the day of installation) or shall be
vented to atmosphere.
A length of uninsulated copper tube no less than ¾”
nominal diameter shall be used at the hot outlet of
the solar collector(s) for a distance of no less than
three feet (3’) before the transition is made to PEX
tubing.
P.8
C-SSN
SUPPORT STRUT
FRONT
MOUNTING FOOT
REAR TELESCOPING LEG
fig. 5
REXRACK

All connections in the PEX piping runs shall be
approved by the PEX manufacturer for potable
water piping.
•The system shall have a pressure-only relief valve
installed at the drainback tank location or shall be
vented to the atmosphere. The pressure rating for
the relief valve shall be no less than 25 psi and no
more than 50 psi.
The collector loop pipe sizing must be adequate-
ly sized to handle the design flow rates for the
collector(s). SunEarth recommends ¾” nominal
diameter pipe sizes for two collector systems and
½” nominal diameter pipe sizes for two collector
systems, except for the return piping from the col-
lector to the drainback reservoir, this should always
be ¾” or larger.
CAUTION: The solar loop piping from the
collector(s) to the drainback tank must be no less
than 3/4” TYPE-M copper tube to allow air to
migrate up the tube ensuring full draining of the
collector(s) and tubes.
It may be necessary to increase the pipe size for lon-
ger pipe runs or reduce the pipe size for shorter runs
or higher efficiency pumps. The pipe must be large
enough that the velocity of the water in the pipe does
not exceed 4 ft/s. Hot water flowing at over 4 ft/s
in a pipe will erode the pipe and reduce system life.
When more than one collector is used in the system,
the collectors should be plumbed in a reverse return
piping arrangement in order to maintain equal flows
through all collectors in the array during normal
operation.
To ensure proper drainage of the collector array
and solar loop piping the lines must be adequately
sloped to drain back to the drainback reservoir.
Figure 6 illustrates correct and incorrect methods of
plumbing the solar collector array. Note that water
will trap in the “U” section of piping as illustrated
in the drawing marked incorrect thus making it sus-
ceptible to freeze damage.
Piping in new solar installations can be covered with
dirt, grease, solder flux or other impurities that may
P.9
Supply Line
1” CC CAP
1” CC COUPLING
1” x ¾” CC 90° ELBOW OR COUPLING
RETURN LINE
1” x ¾” CC 90° ELBOW OR COUPLING
1” CC CAP
1” CC COUPLING
COLLECTOR PLUMBING - SLOPED TO DRAIN
fig. 6

P.10
affect the system performance. A thorough clean-
ing is required before charging. A Water soluble
flux should be used when soldering pipe joints in
the collector loop in order to facilitate system flush-
ing. Carefully review the cleaning procedures in
“Charging the System” outlined below.
All vertical piping between the storage tank and
the collector shall be supported at each story or at
maximum intervals of ten feet (10’). Horizontal
runs shall be sloped to drain (minimum 2% slope)
and supported every five feet (5’) to prevent sag-
ging. Roof runs shall be secured and supported
providing at least 1-1/2 inches clearance from roof.
Pipe supports shall be constructed from a material
that will not rot, compress or degrade over time
as this may lead to pipe sagging and failure to
drain. Standard best piping practices shall be fol-
lowed as described in the Uniform Plumbing Code,
International Plumbing Code or other recognized
code or standard. Plumbers tape or tube strap is
required. The pipe insulation should not be com-
pressed or crimped by the strapping material.
Allowance should be made for expansion and con-
traction of piping due to changes in temperature of
the water and piping. Use flexible pipe supports and
avoid long straight piping runs. Include bends and
elbows to allow for expansion such as swing joints
at the collector inlet & outlet.
The installation of all horizontal and vertical piping
may not reduce the performance or rating of any
structural member or fire rated assembly. Adhere to
all applicable local codes and ordinances.
4.5 Pipe Insulation
WARNING: HOT PIPES MAY CAUSE
BURNS IF TOUCHED. ENSURE THAT
ALL PIPES AND FITTINGS ACCESSIBLE
TO THE PUBLIC ARE WELL INSULATED.
COMPONENTS ACCESSIBLE TO PUBLIC
TRAFFIC MUST BE KEPT BELOW 140ºF
OR CLEARLY LABELLED WITH AN
APPROPRIATE WARNING.
The collector loop piping, plus any interconnecting
hot water piping shall be well insulated with a high
quality flexible closed cell insulation to minimize
heat loss. In addition, the final 5 feet of metallic
cold water supply pipe leading to the system, or
the length of piping which is accessible if less than
5 feet, shall also be insulated. The insulation shall
have a maximum operating temperature of 220°F or
higher and a minimum thermal resistance of R-2.6.
The wall thickness of the pipe insulation should be
½” or thicker. A 1” wall thickness is required for
exposed piping in all areas prone to annual hard
freeze conditions. When it comes to pipe insulation
the rule is simple: thicker is better.
To the extent possible, slide the insulation material
over the pipe without cutting or taping. All butt
joints must be sealed with contact adhesive. The use
of rigid polyethylene pipe insulation is prohibited.
The 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 shall be
protected from UV degradation and moisture dam-
age. Insulation must be jacketed, wrapped with alu-
minum foil tape, or painted with two coats of high
quality water-based acrylic resin coating as supplied
by the insulation manufacturer.
4.6 Control System
4.6.1 Differential Controller
The differential controller must be installed in an
accessible location so that the user interface, typi-
cally and LCD screen, can be seen. Switches on the
controller must be labeled and accessible. Always
follow the controller manufacturers wiring diagram
when installing differential controllers. Control sys-
tem inputs; such as signals from temperature sensors
or flow meters will be connected to the appropriate
low voltage terminals. Controller output to the
pump will be medium voltage, 110 VAC or 220
VAC. Medium voltage power to the pump may be
supplied by a line cord from the pump to an outlet
in the controller or hard wired from the controller
medium voltage terminals to the pump. Wiring
must comply with standard electrical practice and
all applicable electrical codes for the jurisdiction,
this may require the use of conduit for medium volt-
age wiring.
The differential controller must have a provision to
manually turn the pump on and off (manual over-
ride) so that pump operation can be checked at
any time and the pump can be manually stopped if
required for maintenance or troubleshooting pur-
poses.

Set the maximum tank temperature to the desired
maximum temperature, this temperature must be
lower than the rated maximum temperature of the
tank. When the solar loop heats the tank to this tem-
perature, the pump will shut off preventing further
heat gains to the solar tank.
4.6.2 Collector Sensor Placement
The collector sensor shall be located on the hot
water return line as close to the collector as possible.
Sensors are typically accurate to +/- ½°F if prop-
erly installed and weatherized. The collector probe
sensor shall be attached to the SunEarth collector
header pipe either with a stainless steel hose clamp
or by inserting the probe sensor into a thermalwell
in contact with the fluid near the outlet header pipe.
It is recommended that the connection between the
silicon sensor lead and low voltage sensor wiring be
made inside the attic or other indoor space. When
using wire nuts to make the connection, the crimped
brass cap on the end of the sensor wire should be
striped before inserting into the wire nut. Where
connections from the sensor lead to the low volt-
age wiring is made at an exposed location the wire
connection should be protected from degradation
or corrosion from rain, snow and UV radiation.
Connections may be protected by using: crimp and
heat shrink or solder and heat shrink butt connec-
tions; NEMA 4X or other weather resistant connec-
tion boxes. Weather resistant connection boxes with
integral lightening arrestors are also available and
are highly recommended in areas prone to electrical
storms. Wire nuts or screw connectors should not
be exposed to weather due to the likelihood of cor-
rosion which will result in a compromised electrical
connection.
Thoroughly wrap and weatherize the insulation with
electrician’s tape or insulation tape as provided by
the manufacturer. See Figure 8 for collector sensor
installation detail.
If an electrical potential exists between the roof
and ground, this may induce current to flow down
the sensor wire to the controller. This current will
result in a false signal being received by the control-
ler and incorrect temperature readings. To prevent
such current the copper plate and piping should be
independently grounded. This will provide a sepa-
rate path to ground from the roof which does not
interfere with the sensor readings.
Grounding can be achieved by running a separate
ground wire to the collectors or ensuring that the
copper pipe in the closed loop is grounded and there
are no electrical discontinuities between the ground-
ing point and the collector. Grounding of the collec-
tor & roof piping is especially important in locations
that often experience electrical storms and electrical
atmospheric activity.
4.6.3 Low Voltage Wiring
The low voltage wiring used to connect the sensor
lead to the controller shall be a minimum18 AWG.
The wiring should be bare or tinned copper, two
conductor, stranded, PVC insulated, with a PVC UV
rated jacket suitable for exterior use. In locations
that often experience electrical storms and electri-
cal atmospheric activity the low voltage sensor wire
should also be shielded and the shielding connected
to ground.
Low voltage wire shall be rated for the full range
of temperatures expected in the location, typically
wire should be rated up to 160ºF. The low voltage
sensor wire must not be in direct contact with the
copper pipe as the wire insulation may melt when
in contact with hot pipe. Low voltage sensor wire
must be run OUTSIDE the pipe insulation, where
the low voltage wire is run in an exposed location,
P.11
fig. 7

P.12
it should be run OUTSIDE the pipe insulation but
UNDER the insulation jacket or wrap to protect the
wire from UV exposure.
4.7 Installing the Solar Tank
The solar tank is heated indirectly through a double
wall heat exchanger that is integral to the tank. This
kind of heat exchanger wraps around the tank shell
and under the insulation and tank jacket. Any leak
in the heat exchanger will be seen as fluid will leak
out from the bottom tray of the tank jacket.
When plumbing the SunEarth solar storage tank and
drainback reservoir make sure that all the compo-
nents are accessible and easy to reach. Ensure that
there is clear access to the storage tank, circulat-
ing pump, drainback reservoir, mixing valve, flow
meter and other key components. If a component
in the potable water side of the system may require
future service or maintenance make the connections
with brass unions. Use only brass nipples and unions
and copper and brass fittings in plumbing the solar
storage tank and drainback reservoir. The use of
galvanized fittings or nipples, CPVC or PVC piping
is prohibited.
Check valves are NOT ALLOWED anywhere in
the collector loop. A check valve in the collector
loop will prevent proper draining of the collectors
and may result in freeze damage. If the pump used
has an integral check valve, the check valve must be
removed before installing the pump in the system.
Hard copper connections to the city cold water
supply line and the home hot water feed lines are
recommended. The gaskets in standard water heater
flex hose connectors can become brittle and com-
pressed over time and begin leaking on the water
heater. If not detected in a timely manner even a
small drip or leak may cause serious damage to the
tank’s electrical components or, in extreme cases,
may cause the tank to leak from the outside in.
Tank plumbing is required to provide for the isola-
tion of the solar storage tank from the city cold water
supply line by means of an isolating ball valve.
The differential temperature controller shall have a
screen readout to show temperatures of the collec-
tor and storage tank. Otherwise, line thermometers
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 – 15°F
PROTECTIVE INSULATION
JACKET OR APPROVED
COATING
RETURN LINE
CRIMP OR SOLDER
CONNECTION
SENSOR WIRE MUST
NOT BE PLACE IN
DIRECT CONTACT WITH
PIPE
SILICON SENSOR LEAD MAY
BE IN CONTACT WITH PIPE
SENSOR CLAMPED TO HEADER PIPE
& COVERED WITH INSULATION
COLLECTOR SENSOR fig. 8

warmer than the water in the collector supply line.
The specified SunEarth controller continuously
displays the temperature of the SunEarth collectors
(T1) and the temperature at the bottom of the solar
tank (T2). In addition, you may choose to install
a third temperature sensor (T3); this is normally
installed at the hot water outlet on both single and
double tank systems.
The Cascade Drainback system typically requires a
high head, low flow circulating pump. The maxi-
mum head on the pump curve must be greater than
the static lift head required to fill the system. The
static lift head is the vertical height from the bot-
tom of the drainback tank to the highest point in the
system (usually the collector outlet header). When
the pump is filling the system it will be pumping
against the static lift head and should provide no
less than half the design flow of the collector. Once
the system has been filled to the top of the collector,
water will start to cascade down the return line fill-
ing the return line as far as the drainback reservoir.
Once this pipe is fully flooded the return line will
start to siphon, resulting in an increase in flow as
the system transitions from the filling condition to
the running condition. In the running condition the
flow rate should not exceed 4 ft/s. Good pump selec-
tion requires that the pump provide enough lift for
the filling condition without excessive flow in the
running condition. This is usually achieved using
a pump with a “steep” pump curve. For multistory
buildings, this can be especially challenging unless
the drainback tank is located on the upper floor.
When there is a risk of pipe errosion due to high
flow rates, a pump throttling valve (COMPONENT
#22) may be located on the discharge, or upstream,
side of the pump to adjust the solar loop flow rate
and to prevent errosion of solar loop. A throttling
valve on the return piping from the collector to the
drainback tank can also be beneficial in situations
where excessive noise is experienced due to high
flow rates into the drainback reservoir.
A brass boiler drain (COMPONENT #11) must be
installed at the lowest point in the system to allow
for charging the solar loop piping and to serve as a
drain valve for manual draining and maintenance.
P.13
DB-5.0
DB-7.5
DB-10.0
SunEarth
Model No.
12
18
24
Width
Inches
5
5
5
Depth
Inches
50
50
50
Length
Inches
42
56
84
5.0
7.5
10.0
82
117
164
220
220
220
3/4
3/4
3/4
Dry Weight
(lbs)
Fluid Capacity
(US gal)
Max Pressure
(psig)
Connection
Pipe Dia. (in)
Wet Weight
(lbs)
Table 3 - Specification For SunEarth CopperStor Drainback Tank
Max. Temp of 210° F
Array DB 5.0 DB 7.5 DB 10.0
1 EP/EC-40 82 138 194
2 EP/EC-21 76 132 188
2 EP/EC-32 73 129 185
2 EP/EC-32 62 118 174
Pipe run lengths for 1/2” supply and 3/4”
return lines.
Table 1
Array DB 5.0 DB 7.5 DB 10.0
1 EP/EC-40 61 103 144
2 EP/EC-21 57 98 140
2 EP/EC-32 54 96 138
2 EP/EC-32 46 88 130
Table 2
Pipe run lengths for 3/4” supply and return
lines.

A high quality thermostatic mixing valve is a
required component in all OG-300 certified systems
and should be plumbed in line with brass union
connections for ease of future repair or replace-
ment. The mixing valve shall be standard ASSE
1017 approved. The specified mixing valve should
have an operating range between 95°F and 120°F.
The mixing valve shall include a set point of 120°F
delivered water temperature.
WARNING: SCALDING CAN OCCUR
WITHIN FIVE SECONDS WHEN WATER
TEMPERATURES APPROACH 140° F.
DESPITE THE INSTALLATION OF A MIXING
VALVE IN YOUR CASCADE DRAINBACK
SYSTEM, ALWAYS EXERCISE CAUTION
WHEN OPENING A HOT WATER FIXTURE
OR FAUCET IN YOUR HOME.
The 3/4” cold water supply line to the solar storage
tank shall be insulated with R-2.6 or greater pipe
insulation to a minimum distance of 5’ behind the
storage tank, or to the wall if closer than 5’.
The SunEarth solar storage tank model with integral
heat exchanger and auxiliary heating element is the
specified storage tank in your Cascade Drainback
system.
Figures 10, 11 and 12 show the plumbing schemat-
ics for single and two tank Cascade Drainback sys-
tems. A brief explanation of the main components
and their function is found in Section 10 below.
4.8 Tank Sensor Placement
Figures 9details the proper placement of the solar
storage tank sensor. The tank sensor shall have
good thermal contact with the tank wall in order to
accurately measure the temperature of the water at
the bottom of the tank. It is recommended that the
sensor be installed in a brass or copper thermalwell
screwed into the lower sensor port in the tank. With
tanks that have a sensor stud; the probe sensor may
be clipped to the stud using a one hole jiffy clip
(for 3/16” tubing) ensuring good thermal contact
between the sensor and the stud. Thoroughly weath-
erize the wire connections in accordance with the
roof sensor detail above.
4.9 Tank Insulation
SunEarth solar heat exchange tanks have an insula-
tion value of approximately R-17.3.
Conventional back-up electric water heaters have
insulation values between R-12 and R-20. The R
value expresses the thermal resistance of the tank
insulation. The higher the “R-value” value the more
effective the insulation material is at preventing heat
loss. The use of any solar storage tank with and R
value below R12 is prohibited.
The storage tank should not be placed directly on an
uninsulated floor or concrete slab. In order to pre-
vent moisture damage to the base of the tanks and
reduce heat loss to the floor slab, the tank should
be raised off the floor on a pad. The pad should be
of a material that will not rot, compress or degrade
over time.
4.10 Choosing and Installing the Drainback
Reservoir
SunEarth CopperStor copper drainback reservoir
are available in 2.5; 5; 7.5 and 10 gallon capacities.
Stainless steel drainback reservoirs are available in
10 and 15 gallons. Small glass lined steel electric
water heaters available in various sizes from 6 to 20
gallons can also be used as drainback reservoir; do
not connect the heating element when using these
tanks as a drainback reservoir. The minimum
drainback reservoir volume must be DOUBLE the
volume of the piping and collector loop above the
initial fill level of the system. This volume is calcu-
lated from the fluid capacity of all the collectors in
the system plus all piping above the drainback tank
fill level.
Select the appropriate tank based on the collector(s)
chosen and the total length of solar supply and
return loop piping in the system. Table 1 and Table
2 indicate the proper drainback tank for the two
most common piping scenarios. SunEarth recom-
mends using Table 1: 1/2” piping for the supply line
and 3/4” piping for the return line. This provides
some flow related benefits, extends the allowable
pipe run and is slightly less expensive.
The drainback reservoir shall be mounted in a loca-
tion that is NEVER subjected to freezing conditions.
The drainback reservoir may be mounted to a wall
using brackets or on a stand over the solar tank. The
outlet of the drainback reservoir should be at least
48” above the suction side of the circulating pump
to give sufficient net positive suction head available
to the pump (See Figures 10, 11 and 12).
P.14

The drainback reservoir should be installed at the
highest location practicable. The benefits of this
include: reduced risk of pump cavitation; reduced
pumping head required to fill the system allowing
smaller pumps to be used; and reduced piping above
the drainback reservoir allowing smaller drainback
tanks. In buildings with two or more floors, it is
beneficial to install the drainback on the uppermost
floor, preferably near the ceiling.
Drainback reservoirs are factory insulated to pro-
vide both heat retention and a noise buffer against
the sound of falling water.
If your Cascade Drainback system includes the
optional flow meter it should be plumbed so that
the top of the flow meter is level with the top of the
drainback tank so that the flow meter also provides a
visual check of the fluid level in the system. The top
and bottom of the flow meter should be supported to
relieve stresses on the connecting unions.
DO NOT install the pressure relief valve
(COMPONENT #9) on the drainback tank at this
time. The COMPONENT #9 is threaded in place
after the solar loop piping has been filled with water.
See Section 4.13 for instructions on charging the
system.
4.12 Electrical Requirements
When electric element is used as the auxiliary heat
source a properly licensed contractor shall make the
230 VAC electrical connection to the water heater
or solar storage tank. If your solar contractor is not
allowed by law to make these connections consult a
licensed electrician.
Never activate the circuit breaker controlling the
electrical heating element until the solar storage
tank is completely filled with water. This will
prevent “dry firing” of the heating element. The
electrical heating element will be destroyed almost
instantaneously if not completely submerged in
water when activated. Make sure the water heater
circuit breaker is off until the solar storage tank is
completely filled.
We recommend the use of a 115 VAC differential
control with a factory installed six foot line cord.
The installation requires one 115 VAC outlet to
be installed near the solar storage tank. Plug the
control into the outlet. The circulation pump line
cord is plugged into the receptacle on the side of
the controller. A 230 VAC control and circulation
pump may be substituted, but troubleshooting the
components in the future becomes more difficult.
4.13 Heat Transfer Fluid (HTF)
The HTF must be a non-toxic fluid that meets
FDA Generally Recognized as safe (GRAS)
Classification. The Cascade Drainback System uses
water to meet this requirement.
Water used fill the collector loop must meet certain
minimum standards for purity. Impurities in the
dilution water can increase metal corrosion, and
cause the formation of scale and other deposits on
the heat exchanger’s internal heat transfer surfaces.
Distilled or deionized water is recommended.
4.14 Flushing and Filling the System
Once the components have been plumbed it is time
to fill the solar storage and collector loop with water
as follows:
4.14.1 STEP 1 – Fill the solar tank with water and
check that there are no leaks on the potable side of
the system.
Do this by opening the cold water isolation ball
valve to the solar tank (COMPONENT #8) and
opening a hot water outlet, such as a faucet, until the
water runs freely. When the tank is filled, inspect all
threaded fittings and solder joints for leaks.
4.14.2 STEP 2 - Fill the solar loop piping with
water.
First connect a washing machine hose to the boiler
drain (COMPONENT #11) located at the low-
est point in the system. Open the boiler drain
(COMPONENT #11) and begin filling the system
directly from a fixture at mains pressure or by using
a utility pump. If your system has a flow meter
(FM), or sight glass, continue filling the solar loop
piping until the water level is visible. When the
water rises to within 1” of the top of the flow meter
or sight glass, close the boiler drain (COMPONENT
#11). Install the mandatory pressure relief valve
(COMPONENT #9) on top of the drainback res-
ervoir. If your system does not have a flow meter
or sight glass attach a washing machine hose to the
female fitting on top of the drainback reservoir using
an appropriate hose to pipe fitting (3/4” Male Hose
Thread X 3/4” FIP). Place the other end of the hose
in a basin drain or mid-size bucket. Open the lower
boiler drain (COMPONENT #11) and begin filling
the solar loop piping from a tap or by using a utility
P.15

pump. Continue filling the piping until water flows
from the upper hose into the basin or storage bucket.
Close the boiler drain and install the COMPONENT
#9 on the drainback reservoir.
4.14.3 STEP 3 – Run the pump to check operation
and flush impurities from the collector loop.
At this point it is recommended to run water through
the system to remove any solder flux residue or
other impurities that were introduced into the sys-
tem during plumbing. Water soluble flux should
have been used when soldering pipe joints in the
collector loop to facilitate system flushing. Set the
switch on the side of the SunEarth control to the
“ON” position. Allow the pump to circulate water
through the system for 15-20 minutes. While the
pump is running check the entire collector loop for
leaks and ensure that there is adequate flow.
4.14.4 STEP 4 – Check that Collectors are Draining
Back.
Turn the controller back to the ‘OFF’ position.
Allow time for the collectors and piping to drain into
the drainback reservoir. Observe the water level in
the drainback reservoir by means of the site glass,
visual flow meter or by checking with a dowel rod.
The water level in the drainback reservoir should
return to the original fill level after a few minutes.
If the water level does not return to the original fill
level, the system is not draining properly and may
freeze. If water level does not return to original
level, check format that the collectors are tilted
with riser tubes at 15° or more and that all piping is
sloped to drain at 2% or more.
4.14.5 STEP 5 - Drain the system to remove impuri-
ties.
Drain the cycled water out of the array by plac-
ing the hose attached to the lower boiler drain
P.16
TANK SENSOR
THERMOWELL
TANK SENSOR
JIFFY CLIP
fig. 9