Raypak 751 User manual

INSTALLATION AND OPERATING
INSTRUCTIONS
CATALOG NO. 3400.52E Effective: 02-22-07 Replaces: 04-01-03 P/N 241079 Rev. 6
WARNING: Improper installation, adjustment, alteration, service or maintenance can cause property
damage, personal injury or loss of life. Refer to the user’s information manual provided with this boiler.
FOR YOUR SAFETY: Do not store or use gasoline or other flammable vapors and liquids or other
combustible materials in the vicinity of this or any other appliance. To do so may result in an explosion or fire.
WHAT TO DO IF YOU SMELL GAS:
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any phone in your building.
• Immediately call your gas supplier from a neighbor's phone. Follow the gas supplier's instructions.
• If you cannot reach your gas supplier, call the fire department.
Installation and service must be performed by a qualified installer, service agency or the gas supplier.
This manual should be maintained in legible condition and kept adjacent to the heater or in a safe place for future
reference.
Models 751, 1001 &
1501 – Types H, WH & P
Advanced
Design
Boiler
L
W

2

WARNINGS 4
BEFORE INSTALLATION 5
Product Receipt 5
Model Identification 5
Ratings and Certifications 5
Installations at Elevation 5
Component Locations 6
GENERAL SAFETY 7
Time/Temperature Relationships in
Scalds 7
INSTALLATION 8
Installation Codes 8
Equipment Base 8
Clearances 8
Combustion and Ventilation Air 9
Conventional Combustion Air Supply 11
Water Piping 12
Hydronic Heating 13
Gas Supply Connections 21
Electrical Power Connections 23
Venting Connections 25
Venting Installation Tips 27
Venting Configurations 27
Condensate Drain 40
Controls 41
WIRING DIAGRAM 44
PRE START-UP 46
ADB Initial Start-Up 48
OPERATION 51
Lighting Instructions 51
To Turn Off Gas to Appliance 51
MAINTENANCE 51
Suggested Minimum
Maintenance Schedule 51
CONNECTING THE CHX 52
APPENDIX 54
Inside Combustion Air Contamination 54
START-UP CHECKLIST 55
WARRANTY 56
CONTENTS
3

4
DANGER: Indicates the presence of immediate hazards which will cause severe
personal injury, death or substantial property damage if ignored.
WARNING: Indicates the presence of hazards or unsafe practices which could cause
severe personal injury, death or substantial property damage if ignored.
CAUTION: Indicates the presence of hazards or unsafe practices which could cause
minor personal injury or product or property damage if ignored.
NOTE: Indicates special instructions on installation, operation, or maintenance which
are important but not related to personal injury hazards.
DANGER: Make sure the gas on which the heater
will operate is the same type as that specified on the
heater rating plate.
WARNING: Should overheating occur or the gas
supply valve fail to shut, do not turn off or disconnect
the electrical supply to the heater. Instead, shut off
the gas supply at a location external to the heater.
WARNING: Do not use this heater if any part has
been under water. Immediately call a qualified
service technician to inspect the heater and to
replace any part of the control system and any gas
control which has been under water.
WARNING: To minimize the possibility of improper
operation, serious personal injury, fire, or damage to
the heater:
• Always keep the area around the heater free of
combustible materials, gasoline, and other
flammable liquids and vapors.
• Heater should never be covered or have any
blockage to the flow of fresh air to the heater.
WARNING - CALIFORNIA PROPOSITION
65: This product contains chemicals known to the
State of California to cause cancer, birth defects or
other reproductive harm.
WARNING: Risk of electrical shock. More than one
disconnect switch may be required to de-energize
the equipment before servicing.
CAUTION: This heater requires forced water
circulation when the burner is operating. See
minimum and maximum flow rates. Severe damage
will occur if the heater is operated without proper
water flow circulation.
CAUTION: Operation of this heater in low
temperature systems requires special piping to
ensure correct operation.
CAUTION: If this heater is to be installed above
radiation level, it must be provided with a low water
cut-off device at the time of heater installation.
WARNINGS
Pay Attention to These Terms

5
BEFORE INSTALLATION
Raypak strongly recommends that this manual be re-
viewed thoroughly before installing your ADB heater.
Please review the General Safety information before
installing the heater. Factory warranty does not apply
to heaters that have been improperly installed or oper-
ated. (Refer to the warranty at the back of this
manual.) Installation and service must be performed
by a qualified installer, service agency or gas supplier.
If, after reviewing this manual, you still have questions
which this manual does not answer, please contact the
manufacturer or your local Raypak representative.
Thank you for purchasing a Raypak product. We hope
you will be satisfied with the high quality and durability
of our equipment.
Product Receipt
On receipt of your heater it is suggested that you visu-
ally check for external damage to the shipping crate. If
the crate is damaged, make a note to that effect on the
Bill of Lading when signing for the shipment. Remove
the heater from the shipping packaging. Report any
damage to the carrier immediately.
On occasion, items are shipped loose. Be sure that
you receive the correct number of packages as indi-
cated on the Bill of Lading.
Claims for shortages and damages must be filed with
the carrier by consignee. Permission to return goods
must be received from the factory prior to shipping.
Goods returned to the factory without an authorized
Returned Goods Receipt number will not be accepted.
All returned goods are subject to a restocking charge.
When ordering parts, you must specify the model and
serial number of the heater. When ordering under war-
ranty conditions, you must also specify the date of
installation.
Purchased parts are subject to replacement only
under the manufacturer’s warranty. Debits for defec-
tive replacement parts will not be accepted and will be
replaced in kind only per Raypak’s standard war-
ranties.
Model Identification
The model identification number and heater serial
number are found on the heater rating plate located on
the left inside jacket of the heater. The model number
will have the form H4-0751A ADB or similar depending
on the heater size and configuration. The first charac-
ter of the model number identifies application (H =
Hydronic Heating System, W = Hot Water Supply
System, P = Pool Application). The second character
identifies the firing mode (4 = On-Off firing). The next
four places identify the input of the heater in 1,000s of
BTUH 0751 = 750,000 BTUH). The remaining suffix
identifies the control, ignition, and construction config-
uration. The last three characters of the model number
identifies the model type (ADB = Advanced Design
Boiler).
Ratings and Certifications
Standards:
• ANSI Z21.13 · CSA 4.9 - latest edition, Gas-Fired
Hot Water Boilers
• CAN 3.1 - latest edition, Industrial and
Commercial Gas-Fired Package Boilers
• ANSI Z21.10.3 · CSA 4.3 - latest edition, Gas Wa-
ter Heaters
• SCAQMD Rule 1146.2
All Raypak heaters are National Board Approved, and
design-certified and tested by the Canadian Standards
Association (CSA) for the U.S. and Canada. Each
heater is constructed in accordance with Section IV of
the American Society of Mechanical Engineers
(ASME) Heater Pressure Vessel Code and bears the
ASME stamp. The heater also complies with the latest
edition of ASHRAE 90.1 Standard.
Installations at Elevation
No de-rating is required for altitudes up to 7000 feet.
Rated inputs, at sea level settings, are suitable for up
to 5000 feet elevation. At altitudes between 5000 and
7000 feet, rated inputs are achieved with pressure set-
tings adjustment. Consult the factory for installations at
altitudes in excess of 7000 feet.
WARNING: Altering any RAYPAK pressure vessel
by installing replacement heat-exchangers, tube
bundle headers, or any other ASME part not
manufactured and/or approved by RAYPAK will
instantly void the ASME, and agency listings and any
RAYPAK warranty on the vessel. Altering the ASME,
agency ratings of the vessel also violates national,
state, and local approval codes. The terms "boiler"
and "heater" are used interchangeably in this
manual.

6
Component Locations
Fig. 1: Component Locations

7
GENERAL SAFETY
To meet commercial water use needs, an external
operating control for this hot water boiler is adjustable
up to 210°F. However, water temperatures over 125°F
can cause instant severe burns or death from scalds.
The preferred starting point for setting the control for
supplying general purpose hot water is 125°F.
Safety and energy conservation are factors to be con-
sidered when setting the water temperature on the
thermostat. The most energy efficient operation will
result when the temperature setting is the lowest that
satisfies the needs consistent with the application.
Maximum water temperatures occur just after the boil-
er’s burner has shut off. To determine the water
temperature being delivered, turn on a hot water
faucet and place a thermometer in the hot water
stream.
NOTE: When this water heater is supplying general
purpose hot water for use by individuals, a
thermostatically controlled mixing valve for reducing
point of use water temperature is recommended to
reduce the risk of scald injury. Contact a licensed
plumber or the local plumbing authority for further
information.
Water temperature over 125°F can
cause instant severe burns or death
from scalds.
Children, disabled, and elderly are
at highest risk of being scalded.
See instruction manual before set-
ting temperature at water heater.
Feel water before bathing or show-
ering.
Temperature limiting valves are
available, see manual.
Time/Temperature
Relationships in Scalds
The following chart details the relationship of water
temperature and time with regard to scald injury and
may be used as a guide in determining the safest
water temperature for your applications.
Water
Temp.
Time to Produce Serious
Burn
120°F More than 5 minutes
125°F 1-1/2 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 1-1/2 seconds
155°F About 1 second
Table courtesy of The Shriners Burn Institute
Table A: Time to Produce Serious Burn

Equipment Base
The boiler should be mounted on a level, structurally
sound surface. The boiler is approved for and can be
installed on a combustible surface but must NEVER
be installed on carpeting. Gas fueled equipment
installed in enclosed parking garages must be located
at least 18 inches above the floor.
In addition, the boiler shall be installed such that the
gas ignition system components are protected from
water (dripping, spraying, rain, etc.) during appliance
operation and service (circulator replacement, control
replacement, etc.).
Clearances
Indoor Installations
8
Table B: Clearances – Indoor Installations
INSTALLATION
INSTALLATION
Installation Codes
Installations must follow these codes:
• Local, state, provincial, and national codes, laws,
regulations and ordinances
• National Fuel Gas Code, ANSI Z223.1/NFPA 54 –
latest edition (NFGC)
• National Electrical Code, ANSI/NFPA 70 - latest
edition (NEC)
• Standard for Controls and Safety Devices for
Automatically Fired Boilers, ANSI/ASME CSD-1,
(CSD-1) when required
• For Canada only: CAN/CSA B149 Installation
Code and CSA C22.1 C.E.C. Part 1 (C22.1)
The temperature of the water in the hot water boiler
can be regulated by setting the temperature dial on
front of the thermostat. To comply with safety regula-
tions the thermostat was set at its lowest setting before
the hot water boiler was shipped from the factory. The
illustration below shows the thermostat and how to
adjust the water temperature.
To adjust the water temperature, insert a small straight
screwdriver into slotted screw in hole in front of ther-
mostat and turn wheel to desired setting.
CAUTION: Hotter water increases the risk of
scalding! There is a hot water scald potential if the
thermostat is set too high.
Adjustment
Screw
Auto Limit
*DO NOT install on carpeting.
CAUTION: The boiler should be located in an area
where water leakage will not result in damage to the
area adjacent to the appliance or to the structure.
When such locations cannot be avoided, it is
recommended that a suitable catch pan, adequately
drained, be installed under the appliance. The pan
must not restrict air flow.
Heater Side Min. Clearance from
Combustible Surfaces
Floor *
Rear 12” (water side)
Right 1”
Left 1”
Top 0”
Vent 1”

9
Outdoor Installations
Raypak Advanced Design Boilers are design certified
by CSA for outdoor installation. Roof water drainage
must be diverted away from boilers installed under
overhangs.
Combustion and Ventilation Air
Indoor Units
The boiler must be supplied with sufficient quantities of
non-contaminated air to support proper combustion
and equipment ventilation. Combustion air can be sup-
plied via conventional venting, where combustion air is
drawn from the area immediately surrounding the boil-
er, or via direct vent, where combustion air is drawn
directly from outside. All installations must comply with
the requirements of NFGC for U.S., CSA B149 for
Canada, and all local codes.
Direct Vent
If outside air is drawn through a vent pipe directly to
the unit for combustion:
1. Install combustion air direct vent in accordance
with the Venting section of this manual.
2. Provide for adequate ventilation of the space
occupied by the boiler(s) by an opening(s) for ven-
tilation air at the highest practical point
communicating with the outdoors. The total cross
sectional area shall be at least one (1) square inch
of free area per 20,000 BTUH of total input rating
of all equipment in the room when the opening is
communicating directly with the outdoors or
through vertical duct(s). The total cross sectional
area shall be at least one (1) square inch of free
area per 10,000 BTUH of total input rating of all
equipment in the room when the opening is com-
municating with the outdoors through horizontal
duct(s).
3. In cold climates, and to mitigate potential freeze-
up, Raypak highly recommends the installation of
a motorized sealed damper to prevent the circula-
tion of cold air through the boiler during the
non-operating hours.
NOTE: In calculating free area, the required size of
openings for combustion, ventilation, and dilution air
shall be based on net free area of each opening. If
the free area through a design of louver or grill is
known, it shall be used in calculating the size
opening required to provide the free area specified.
For additional information, refer to the latest NFGC
code requirements.
Fig. 2: Minimum Clearances from Combustible
Surfaces
Heater Side Min. Clearance from
Combustible Surfaces
Rear 12” (water side)
Right 36”
Left 36”
Top 0”
Vent 1”
Table C: Clearances – Outdoor Installations
WARNING: Combustion air inlet (blower air inlet)
should have 6" minimum clearance from any
obstruction, i.e. walls or other appliances.
CAUTION: Remove the screen off the blower inlet
and install a screen (1/2"-3/4" mesh) on the inlet
elbow.

10
U.S. Installations1Canadian Installations2
AClearance above grade, veranda, porch,
deck, or balcony 1 ft (30 cm) 1 ft (30 cm)
BClearance to window or door that may be
opened
4 ft (1.2m) below or to side
of opening; 1 foot (30 cm)
above opening
3 ft (91 cm)
C Clearance to permanently closed window **
D
Vertical clearance to ventilated soffit located
above the terminal within a horizontal dis-
tance of 2 ft (61cm) from the centerline of the
terminal
5 ft (1.5m) *
E Clearance to unventilated soffit **
F Clearance to outside corner **
G Clearance to inside corner 6 ft (1.83m) *
HClearance to each side of center line ex-
tended above meter/regulator assembly *
3 ft (91 cm) within a height
15 ft above the me-
ter/regulator assembly
I Clearance to service regulator vent outlet *6 ft (1.83m)
J
Clearance to non-mechanical air supply inlet
to building or the combustion air inlet to any
other appliance
4 ft (1.2m) below or to side
of opening; 1 ft (30 cm)
above opening
3 ft (91 cm)
K Clearance to mechanical air supply inlet 3 ft (91 cm) above if within
10 ft (3m) horizontally 6 ft (1.83m)
LClearance above paved sidewalk or paved
driveway located on public property 7 ft (2.13m) 7 ft (2.13m) t
MClearance under veranda, porch, deck or
balcony *12 in. (30 cm) TT
1In accordance with the current ANSI Z223.1/NFPA 54 National Fuel Gas Code
2In accordance with the current CAN/CGA-B149 Installation Codes
t Vent terminal shall not terminate directly above sidewalk or paved driveway located between 2 single family dwellings that serves
both dwellings
TT Permitted only if veranda, porch, deck, or balcony is fully open on a minimum of two sides beneath the floor and top of terminal and
underside of veranda, porch, deck or balcony is greater than 1 ft (30cm)
* Clearances in accordance with local installation codes and the requirements of the gas supplier
Fig. 3: Minimum Clearances from Vent/Air Inlet Terminations – Indoor and Outdoor Installations
Table D: Vent/Air Inlet Termination Clearances

11
Conventional Combustion Air
Supply
U.S. Installations
All Air from Inside the Building
If all combustion air is drawn from the air inside the
building (the mechanical equipment room does not
receive air from outside):
1. The mechanical equipment room must be provid-
ed with two permanent openings communicating
directly with additional room(s) of sufficient volume
so that the combined volume of all spaces meets
the criteria for an unconfined space. (An uncon-
fined space is defined as a space whose volume
is more than 50 cubic feet per 1,000 BTUH of the
aggregate input rating of all appliances installed in
that space.)
2. Each opening must have a minimum free area of
one (1) square inch per 1,000 BTUH of the total
input rating of all gas utilization equipment in the
mechanical equipment room.
3. One opening must commence within twelve (12)
inches of the top, and one opening must com-
mence within twelve (12) inches of the bottom of
the room.
4. Refer to NFGC, Part 5, for additional information.
All Air from Outdoors
If all combustion air is drawn from the air outside the
building (the mechanical equipment room directly
communicates with the outdoors), either of the follow-
ing two methods can be used:
Method 1:
1. The mechanical equipment room must be provid-
ed with two permanent openings, one
commencing within (twelve) 12 inches of the top,
and one commencing within twelve (12) inches of
the bottom of the room.
2. The openings must communicate directly, or by
ducts, with the outdoors.
3. Each opening must have a minimum free area of
one (1) square inch per 4,000 BTUH of total input
rating of all equipment in the room when the open-
ing is communicating directly with the outdoors or
through vertical ducts. The minimum free area
required for horizontal ducts is one (1) square inch
per 2,000 BTUH of total input rating to all the
equipment in the room.
4. Refer to NFGC, Part 5, for additional information.
Refer to Appendix A for additional information
about combustion air quality.
Method 2 (normally applied in cold climate regions):
1. The mechanical equipment room must be provid-
ed with at least one permanent opening,
commencing within 12 inches of the top of the
enclosure.
2. The opening must communicate directly or by
ducts with outdoors.
3. The opening must have a minimum free area of 1
sq. in per 3000 BTUH of the total input rating of all
equipment in the room, or no less than the sum of
the areas of all vent connectors in the confined
space. Refer to the latest version of NFGC, part 5
for additional information.
1. Ventilation of the space occupied by the boiler
shall be provided by an opening(s) for ventilation
air at the highest practical point communicating
with outdoors. The total cross-sectional area of
such an opening(s) shall be at least 10% of the
area required in (2) and (3), but in no case shall
the cross-sectional area be less than 10 square
inches (6500 square mm).
2. When air supply is provided by natural air flow
from the outdoors for natural draft, partial fan
assisted, fan-assisted or power draft-assisted
burners, there shall be a permanent air supply
opening(s) having a cross section area of not less
than 1 sq. in. per 7000 BTUH (310 sq. mm per kW)
up to and including 1 million BTUH, plus 1 sq. in.
per 14000 BTUH (155 sq. mm per kW) in excess
WARNING: Do not use one permanent opening
method (Method 2) if the equipment room is under
negative pressure condition or the equipment is
common vented with other gas-fired appliances.
Canadian Installations
CAUTION: All combustion air has to be drawn from
the air outside the building (the mechanical
equipment room directly communicates with the
outdoors).

of 1 million BTUH. This opening(s) shall be either
located at or ducted to a point neither more than
18 inches (450 mm) nor less than 6 inches (150
mm) above the floor level. The duct can also
"Goose Neck" through the roof. The duct is pre-
ferred straight down 18 inches from floor, but do
not place near piping. This air supply opening
requirement shall be in addition to the air opening
for ventilation air required in (1).
3. When air supply is provided by natural air flow
from outdoors for a power burner and there is no
draft regulator, draft hood or similar flue gas dilu-
tion device installed in the same space, in addition
to the opening for ventilation air required in (1),
there shall be a permanent air supply opening(s)
having a total cross-sectional area of not less than
1 sq. in. for each 30,000 BTUH (70 sq. mm per
kW) of total rated input of the burner(s), and the
location of the opening(s) shall not interfere with
the intended purpose of the opening(s) for ventila-
tion air referred to (1). This opening(s) can be
ducted to a point neither more than 18 inches (450
mm) nor less than 6 inches (150 mm) above the
floor level. The duct can also "Goose Neck"
through the roof. The duct is preferred to be
straight down 18 inches from floor, but do not
place near piping.
4. Refer to the latest version of CSA B149 for addi-
tional information.
WATER PIPING
General
The boiler should be located so that any water leaks
will not cause damage to the adjacent area or struc-
tures.
All units should be plumbed in accordance with the
appropriate diagram from the following sections or per
a suitable engineered piping arrangement.
12
Relief Valve Piping
Hydrostatic Test
Unlike many other types of boilers, Raypak boilers do
not require hydrostatic testing prior to being placed in
operation. The heat exchanger has already been fac-
tory-tested and is rated for 160 PSI operating
pressure. However, Raypak does recommend hydro-
statically testing the piping connections to the boiler
and the rest of the system prior to operation. This is
particularly true for hydronic systems using expensive
glycol-based antifreeze. Raypak recommends con-
ducting the hydrostatic test before connecting gas
piping or electrical supply.
Leaks must be repaired at once to prevent damage to
the boiler. NEVER use petroleum-based stop-leak
compounds.
1. Connect fill water supply. Fill boiler with water (be
sure bleed valve is open). When water flows from
bleed valve, shut off water. Close bleed valve.
Carefully fill the rest of the system, being sure to
eliminate any entrapped air by using high point
vents. Close feed valve. TEST AT standard oper-
ating pressure for at least 24 hours.
2. Make sure constant gauge pressure has been
maintained throughout test.
3. Check for leaks. Repair if found.
Low Temperature System
Boiler requires minimum inlet temperature of 105°F.
Consult the following sections for piping details. (For
Pool temperature requirements, See the Pool Heating
Section).
Temperature & Pressure
Gauge
The temperature and pressure gauge is factory-
mounted in the inlet/outlet header.
WARNING: Pressure relief valve discharge piping
must be piped near the floor close to a floor drain to
eliminate the potential of severe burns. Do not pipe
to any area where freezing could occur. Refer to
local codes.
CAUTION: This boiler requires forced water
circulation when the burner is operating. See Table E
for minimum and maximum flow rates and water
pump selection. The pump must be interlocked with
the boiler to prevent boiler operation without water
circulation.

HYDRONIC HEATING
Pump Selection
In order to ensure proper performance of your boiler
system, you must install a properly sized pump.
Raypak recommends using a 20°F ΔT as design ΔT.
(ΔT is the temperature difference between the inlet
and outlet water when the boiler is firing at full rate). If
a ΔT larger than 20°F is necessary, the bypass must
be installed and adjusted to ensure proper hydraulics
through the boiler while still allowing minimum flow to
satisfy the safety flow switch. See Table E for flow rate
requirements.
Pressure Drop in Feet of Head
Feedwater Regulator
Raypak recommends that a feedwater regulator be in-
stalled and set at 12 psi minimum pressure at the
highest point of the system. Install a check valve or
back flow device upstream of the regulator, with a
manual shut-off valve as required by local codes.
Piping — Heating Boilers
All high points should be vented. Purge valves and a
bypass valve should be installed. A boiler installed
above radiation level must be provided with a low
water cutoff device. The boiler, when used in connec-
tion with a refrigeration system, must be installed so
the chilled medium is piped in parallel with the boiler
with appropriate valves to prevent the chilled medium
from entering the boiler.
13
The boiler piping system of a hot water heating boiler
connected to heating coils located in air handling units
where they may be exposed to circulating refrigerated
air, must be equipped with flow control valves or other
automatic means to prevent gravity circulation of the
boiler water during the cooling cycle. It is highly recom-
mended that the piping be insulated.
Air-Separation/Expansion Tank
All boilers should be equipped with a properly sized
expansion tank with an air separation fitting as shown
in the following diagrams.
Three-Way Valves
Valves designed to blend water temperatures or
reduce water circulation through the boiler should not
be used. Raypak heaters are high recovery low mass
heaters not subject to thermal shock. Raypak offers a
full line of electric sequencers that produce direct reset
of boiler water temperature. Refer to the Controls
Section in our Complete Catalog.
Table D-1
40°F
ΔP Should include typical piping To/From a single tank as well as bypass piping.
Table E: Rate of Flow and Pressure Drop
NOTE: gpm flow rates limited by maximum
acceptable velocity through heat exchanger tubes.
May be increased by 10% for closed heating
systems. Pressure drop would increase by 21%.

14
Fig. 4: Single Boiler - Primary/Secondary Piping
Fig. 5: Single Boiler - Primary/Secondary Piping with CHX

15
Fig. 6: Dual Boiler Piping
Fig. 7: Dual Boiler - Piping with CHX

16
Fig. 8: Single Boiler - Low Temperature Application (Heat Pump) Primary/Secondary Piping
DOMESTIC HOT WATER
PIPING
When designing the water piping system for domestic
water applications, water hardness should be consid-
ered. Table F indicates the suggested flow rates for
Table F: Domestic Water Heating Boiler Flow Rate Requirements
ΔT=Temperature rise in °F
GPM=Gallons per minute
See Table D for Pressure Drop
soft, medium and hard water. Hardness is specified as
grains per gallon.

17
Fig. 9: Single Boiler - Domestic Hot Water with One Storage Tank
Fig. 10: Single Boiler - Domestic Hot Water with One Storage Tank and CHX

18
Fig. 11: Single Boiler - Domestic Hot Water with One Storage Tank and CHX (2 pump system)
Fig. 12: Single Boiler - Domestic Hot Water with One Storage Tank, One Pre-Heat Tank and CHX

19
POOL HEATING
The ADB unit is equipped with an external pump and
bypass arrangement that blends outlet water with the
inlet to increase the inlet water temperature, thereby
reducing the likelihood of condensation forming on the
heat exchanger. The pump also serves to circulate
water through the heater form the main system piping.
To complete the installation of the pool heater, the pool
thermostat needs to be installed in the main return
water line. This will ensure that the heater will be ener-
gized at the right time. If the main water line is too far
away from the heater and the capillary bulb will not
reach it, locate the pool thermostat adjacent to the
main line and run wires back to the heater. See Figure
13 and 14.
Adjustment of the bypass valve is critical to proper
operation of the heater. The bypass valve should be
adjusted to achieve a minimum inlet water tempera-
ture of 105°F and an outlet water temperature of
125°F. When starting with a cold pool, make initial
adjustments. Make final adjustments when pool water
approaches desired temperature. Refer to Table G for
flow rates.
CAUTION: Power to the heater should be
interlocked with the main system pump to make sure
the heater does not fire without the main system
pump in operation. Improper flow control can
damage the heater. Uncontrolled flow (too high) or
restricted flow (too low) can seriously affect heater
operation. Follow these instructions to make sure
your heater is properly installed.
Table G: Flow Rates
*Loop is secondary piping to heater from main system
CAUTION: ADB bypass piping should be copper
and/or CPVC. PVC piping should NOT be used.
Automatic Chlorinators and
Chemical Feeders
All chemicals must be introduced and completely dilut-
ed into the pool or spa water before being circulated
through the heater. Do not place chlorine tablets or
bromine sticks in the skimmer. High chemical concen-
trations will result when the pump is not running (i.e.
overnight).
Chlorinators must feed downstream of the heater and
have an anti-siphoning device to prevent chemical
backup into the heater when the pump is shut off.
Winterizing Your Heater
When heaters installed outdoors in freezing climate
areas are to be shut down for the winter, please
observe the following procedure:
1. Turn off manual main gas and main gas shut off.
Remove the drain plug or open the drain valves
located on the bottom header.
Pool and Spa Water Chemistry
NOTE: High chemical concentrates from feeders
and chlorinators that are out of adjustment will cause
very rapid corrosion to the heat exchanger in the
heater. Such damage is not covered under the
warranty.
NOTE: Chemical imbalance can cause severe
damage to your heater and associated equipment.
Maintain your water pH between 7.4 and 7.8 and
total alkalinity between 100 and 150 p.p.m. If the
mineral content and dissolved solids in the water
become too high, scale forms inside the heat
exchanger tubes, reducing heater efficiency and also
damaging the heater (max TDS at 3000 ppm). If the
pH drops below 7.2, the heater will be severely
damaged.
NOTE: Heat exchanger damage resulting from
chemical imbalance is not covered under the
warranty.

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Fig. 13: Single Boiler - Pool Application
Fig. 14: Single Boiler - Pool Application with CHX