Raypak Raytherm P-1826 Manual

INSTALLATION & OPERATING
INSTRUCTIONS
CATALOG NO. 6200.51T Effective: 05-15-18 Replaces: 07-01-16 P/N 240251 Rev. 21
WARNING: If these instructions are not followed exactly, a fire or explosion may
result causing property damage, personal injury or death.
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 another safe place for
future reference.
Models P-926 to P-1826
& P-2100 to P-4001
Raytherm
Commercial
Swimming
Pool
Heater
®

2
WATER CHEMISTRY
(Corrosive water voids all warranties)
For your health and the protection of your pool equipment, it is essential that your
water be chemically balanced. The following levels must be used as a guide for bal-
anced water.
Recommended Level(s) Fiberglass Pools Fiberglass Spas Other Pool & Spa
Types
Water Temp. (Deg. F) 68 to 88 89 to 104 68 to 104
pH 7.3 to 7.4 7.3 to 7.4 7.6 to 7.8
Total Alkalinity (PPM) 120 to 150 120 to 150 80 to 120
Calcium Hardness (PPM) 200 to 300 150 to 200 200 to 400
Salt (PPM) 6000 MAXIMUM 6000 MAXIMUM 6000 MAXIMUM
Free Chlorine (PPM)* 2 to 3 2 to 3 2 to 3
Total Dissolved Solids
(PPM) 3000 MAXIMUM 3000 MAXIMUM 3000 MAXIMUM
* Free Chlorine MUST NOT EXCEED 5 PPM!
• Occasional chemical shock dosing of the pool or spa water should not damage the
heater providing the water is balanced.
• Automatic chemical dosing devices and salt chlorinators are usually more efficient
in heated water, unless controlled, they can lead to excessive chlorine level which
can damage your heater, and which is not covered under warranty.
• Further advice should be obtained from your pool or spa builder, accredited pool
shop, or chemical supplier for the correct levels for your water.
Revision 21reflects the following changes:
Removed California Proposition 65 on page 4.

CONTENTS
3
WATER CHEMISTRY 2
WARNINGS 4
Pay Attention to These Terms 4
RECEIVING EQUIPMENT 5
GENERAL
SPECIFICATIONS 5
INSTALLATION 5
Code Requirements 5
Base Installation 5
Clearances 6
Combustion Air (Indoor Units Only) 6
Venting Connections 7
Gas Supply Connections 8
Water Connections 10
CONTROLS 10
Flow Switch 10
Water Pressure Switch 11
Automatic Chlorinators and Chemical
Feeders 11
Unitherm Governor Operation 11
Companion Flange Connections
(Models 926-1223) 11
Mounting the Poolstat Control with Front-
Mounted Loop Using Mounting Slots 12
Mounting Well into System Return Loop
Pipe - Front-Mounted Loop 14
Piping Configurations for Raytherm
Commercial Pool Heaters (926-1223) 15
Piping Configurations for Raytherm
Commercial Pool Heaters (1287-1826) 16
Piping Configurations for Raytherm
Commercial Pool Heaters (2100-4001) 17
Temperature Controls 18
External Auxiliary Bypass Valve (Where
Required) Models 926-1223 Only 18
Auxiliary Bypass Valve Adjustment 18
Electrical Wiring 19
Wiring Diagram—Models 926–1223
with UG 20
Wiring Diagram—Models 926–1826
with H-Bypass 21
Wiring Diagram—Models 2100–2500 22
Wiring Diagram—Models 3001–4001 23
SERVICING 24
General Location Of Controls 24
Temperature Control 24
Pressure Switch 24
Pressure Switch Adjustment 24
Two-Speed Pumps 25
Pilot Safety 25
START-UP PROCEDURES 25
Before Start-Up 25
Start-Up 25
After Start-Up 26
INSPECTION PROCEDURES 26
Burners 26
CONTROLS 26
SERVICING PROCEDURES 27
Tube Cleaning Procedure (Typical) 27
Heat Exchanger Reassembly 27
Burner Drawer Removal 27
Gas Valve Removal 27
Main Burner and Orifice Removal 28
Pilot Removal and Cleaning 28
Heat Exchanger Removal 28
Combustion Chamber Removal 29
Control Well Replacement 29
Tube Replacement Procedure 29
Procedure For Cleaning Flue Gas
Passageways 29
Unitherm Governor Replacement 30
MAINTENANCE AND CARE 30
Winterizing Your Heater 31
TROUBLESHOOTING 32

4
DANGER: Indicates the presence of immediate hazards which will cause severe person-
al 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 flam-
mable liquids and vapors.
• Heater should never be covered or have any
blockage to the flow of fresh air to the heater.
WARNING: Risk of electrical shock. More than one
disconnect switch may be required to deenergize the
equipment before servicing.
CAUTION: Operation of this heater in low-
temperature systems requires special piping.
Harmful internal condensation will occur if the inlet
water temperature does not exceed 105°F. Warranty
claims will be denied when condensation occurs.
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.
CAUTION: If this heater is to be installed in a
negative or positive pressure equipment room, there
are special installation requirements. Consult factory
for details.
WARNINGS
Pay Attention to These Terms

5
RECEIVING EQUIPMENT
On receipt of the equipment, visually check for exter-
nal damage to the carton or the shipping crate. If the
carton or shipping crate is damaged, make a note on
the Bill of Lading and report the damage to the Carrier
immediately. Remove the heater from the carton or
shipping crate. Do NOT use the shipping base crate
as an installation base.
On occasion, we ship some items loose. Be sure that
you receive the number of packages indicated on the
Bill of Lading. When ordering parts, you must specify
Model and Serial Number of heater. When ordering
under warranty conditions, you must also specify date
of installation.
Raypak recommends that this manual be reviewed
thoroughly before installing your Raypak Pool Heater.
If there are any questions which this manual does not
answer, please contact the factory or your local
Raypak representative.
Claims for shortages and damages must be filed with
carrier by consignee. Permission to return goods must
be factory authorized and are subject to a stocking
charge.
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 our standard warranties.
GENERAL
SPECIFICATIONS
Models 962, 1125, 1223, 1336, 1468, 1631, 1826 &
2100 through 4001 are specifically designed for indoor
installation ONLY. Models 926, 1083, 1178, 1287,
1414, 1571 & 1758 are specifically designed for out-
door installation ONLY. All heaters are standard with
electronic ignition for both natural and propane appli-
cations. Heaters require 120V power supply. Control
circuits operate at 24V, supplied by an internal 120V
to 24V transformer.
These heaters are design certified and tested under
the requirements of ANSI Z21.56 / CSA 4.7 American
National Standard for Gas-Fired Pool Heaters. Rated
inputs are suitable for up to 2000 feet elevation. For
elevations above 2000 feet, reduce input 4% for each
1000 feet above sea level, as high elevation reduces
combustion performance.
INSTALLATION
These instructions are intended for the use of qualified
personnel only, specifically trained and experienced in
the installation of this type of heating equipment and
related system components. Installation and service
personnel may be required by some states to be
licensed. If your state is such, be sure your contractor
bears the appropriate license. Persons not qualified
shall not attempt to fix this equipment nor attempt
repairs according to these instructions.
Code Requirements
The heater should not be located in an area where
possible water leakage will result in damage to the
area adjacent to the appliance or to the structure.
When such locations cannot be avoided, it is recom-
mended that a suitable drain pan, adequately drained,
be installed under the appliance. The pan must not
restrict combustion air flow.
Installation must be in accordance with local codes, or,
in the absence of local codes, with the latest editions
of the National Fuel Gas Code (NFGC), ANSI Z223.1/
NFPA 54, and National Electrical Code (NEC), ANSI/
NFPA 70.
Base Installation
Do NOT use the shipping base crate as an installation
base. Heater must be mounted on a level base, such
as cement slab, cement blocks or other non-com-
bustible surface. An optional non-combustible base
is available for Indoor Models 962 through 1826. An
alternative method for providing a base for combus-
tible floors as illustrated below. Heaters may not be
installed on carpeting.
Fig. 1: Alternate Mounting Base
WARNING: Improper installation, adjustment,
alteration, service or maintenance may damage the
equipment, create a hazard resulting in asphyxiation,
explosion or fire, and will void the warranty.

6
Clearances
All Heaters
For clearances from combustible surfaces, see
Table A below. A minimal vertical clearance of three
feet between the upper surface of the flue outlet to a
noncombustible material is required.
For servicing, provide at least 24” in front of the heater
on Models 926-1826 & 48” in front of the heater on
Models 2100-4001 for burner tray removal, and at
least 18” on the right side of the heater to inspect and
delime the heat exchanger.
Outdoor Heaters (Models 926-1758)
These heaters are design-certified for outdoor installa-
tion, when equipped with the approved top designated
for outdoor use. Heaters must not be installed under
an overhang of less than three (3) feet from the top of
the heater. Three (3) sides must be open in the area
under the overhang. Roof water drainage must be
diverted away from heaters installed under overhangs
with the use of gutters.
The point from where the flue products exit the heater
must be a minimum of four (4) feet below, four (4) feet
horizontally from or one (1) foot above any door, win-
dow or gravity inlet to a building. The top surface of
the heater shall be at least three (3) feet above any
forced air inlet, or intake ducts located within ten (10 )
feet horizontally.
High Wind Conditions
(Outdoor Units Only)
In areas where high winds are frequent, it may be nec-
essary to locate the heater a minimum of 3’ from high
vertical walls, or install a wind break so the heater is
not in direct wind current.
Indoor Heaters
The design is certified for indoor installation when
equipped with approved drafthood. Locate the heater
as close as practical to a chimney or gas vent.
Combustion Air
(Indoor Units Only)
The heater must have both combustion and ventila-
tion air. Openings must not be obstructed. Minimum
requirements are from the National Fuel Gas Code
Indoor Heaters Outdoor Heaters (926–
1758)
Heater
Side
Clearance
(Inches)
Heater
Side
Clearance
(Inches)
Top 24 Top 24
Back 24 Back 24
Right Side 24 Right Side 24
Left Side 24 Left Side 24
Vent* 6
Table A: Minimum Clearances from Combustible
Construction
*Vent includes factory supplied drafthood and does not include field
supplied vent systems above the drafthood. On Models 2100-4001
drafthood is built into heater.
For servicing provide a front clearance as shown below:
Model 926/962-758/1826 - 24”
Model 2100-4001 - 48”
WARNING: The heater shall not be located in an
area where water sprinklers, or other devices, may
cause water to spray through the cabinet louvers
and into the heater. This could cause heavy internal
rusting or damage some electrical components, and
this would void the warranty.
Fig. 2: Minimum Distance from Openings
CAUTION: Combustion air must not be
contaminated by corrosive chemical fumes which
can cause unwarrantable damage to the heater.

7
(ANSI Z223.1/NFPA 54).
The “two-opening” method requires:
1. Free combustion air 1 sq. in. per 1000 BTU input
within 12” of the floor.
2. Free ventilation air 1 sq. in. per 1000 BTU input
within 12” of the ceiling level.
Venting Connections
Drafthood (Indoor) Models 962-1826
Locate and assemble as shown in Fig. 3. Secure with
screws supplied in envelope in carton. Do not modify
the drafthood. The height of the relief openings above
the cabinet is critical to proper operation.
Models 2100-4001 have built-in drafthoods that must
be properly vented to the outside.
Vent Piping
Vent piping the same size or larger than the drafthood
outlet is recommended, however, when the total vent
height is at least ten (10) feet (drafthood relief opening
to vent terminal), the vent pipe size may be reduced
as specified in the National Fuel Gas Code, ANSI
Z223.1/NFPA 54 - latest edition. Avoid long horizontal
runs of vent pipe and too many elbows. If installa-
tion requires horizontal or non-vertical runs, the vent
pipe must have a minimum of 1/4 inch per foot rise
and should be supported at not more than five foot
intervals. Plumber’s tape, criss-crossed, will serve to
space both horizontal and vertical piping.
Gas vents supported only by the flashing and extend-
ing above the roof more than five feet should be
securely guyed or braced to withstand snow and wind
loads. We recommend use of insulated vent pipe
spacer through the roofs and walls.
For protection against rain or blockage by snow, the
vent pipe must terminate with a vent cap which com-
plies with the local codes or, in the absence of such
codes, to the latest edition of the National Fuel Gas
Code, ANSI Z223.1/NFPA 54.
The discharge opening must be a minimum of two feet
vertically from the roof surface and at least two feet
higher than any part of the building within ten feet.
Vent stack shall be at least five feet in vertical height
above the drafthood outlet. The vent cap location shall
have a minimum clearance of 4 feet horizontally from,
and in no case above or below, unless a 4-foot hor-
izontal distance is maintained, from electric meters,
gas meters regulators and relief equipment.
The weight of the vent stack or chimney must not rest
on heater drafthood. Support must be provided in
compliance with applicable codes. The heater top
and drafthood must be readily removable for mainte-
nance and inspection. Vent pipe should be adequately
supported to maintain proper clearances from com-
bustible construction.
Type “B” double-wall or equivalent vent pipe, certified
for Category I conditions, is recommended. However,
single-wall metal vent pipe may be used as specified
in the latest edition of the National Fuel Gas Code
ANSI Z223.1/NFPA 54.
NOTE: If the room the heater is installed in is
located against an outside wall and air openings
communicate directly with the outdoors, the openings
may be 1/4 the size specified above (ANSI Z223.1/
NFPA 54, latest edition)
Fig. 3: Indoor Drafthood
WARNING: An indoor heater requires a drafthood
that must be connected to a vent pipe and properly
vented to the outside. Failure to follow this procedure
can cause fire or fatal carbon monoxide poisoning.
5' MIN
2' MIN
10' OR LESS
2' MIN
VENT CAP
VENT PIPE
DRAFT HOOD
HEATER
Fig. 4: Venting Clearances

8
At the time of removal of an existing heater, the fol-
lowing steps shall be followed with each appliance
remaining connected to the common venting system
placed in operation, while the other appliances remain-
ing connected to the common venting system are not
in operation.
(a) Seal any unused openings in the common venting
system.
(b) Visually inspect the venting system for proper
size and horizontal pitch and determine there is
no blockage or restriction, leakage, corrosion and
other deficiencies which could cause an unsafe
condition.
(c) Insofar as is practical, close all building doors and
windows and all doors between the space in which
the appliances remaining connected to the com-
mon venting system are located and other spaces
of the building. Turn on clothes dryers and any
appliance not connected to the common venting
system. Turn on any exhaust fans, such as range
hoods and bathroom exhausts, so they will oper-
ate at maximum speed. Do not operate a summer
exhaust fan. Close fireplace dampers.
(d) Place in operation the appliance being inspected.
Follow the lighting instructions. Adjust thermostat
so appliance will operate continuously.
(e) Test for spillage at the drafthood relief opening
after 5 minutes of main burner operation. Use the
flame of a match or candle, or smoke from a ciga-
rette, cigar or pipe.
(f) After it has been determined that each appliance
remaining connected to the common venting sys-
tem properly vents when tested as outlined above,
return doors, windows, exhaust fans, fireplace
dampers and any other gas burning appliance to
their previous conditions of use.
(g) Any improper operation of the common venting
system should be corrected so the installation
conforms with the latest edition of the National
Fuel Gas Code, ANSI Z223.1/NFPA 54. When
re-sizing any portion of the common venting
system, the common venting system should be
re-sized to approach the minimum size as deter-
mined using the appropriate tables in the National
Fuel Gas Code, ANSI Z223.1/NFPA 54.
For special venting applications that require reduced
vent sizes or through-the-wall venting, the optional D
Series Power Vent can be used. Consult the factory or
your local Raypak representative.
Gas Supply Connections
Per NFGC requirements, gas piping must have a
sediment trap ahead of the heater gas controls, and a
manual shut-off valve located outside the heater jack-
et. All gas piping should be tested after installation in
accordance with local codes.
A minimum of 7 in. WC and a maximum of 10.5 in. WC
upstream pressure under load, and no load conditions
must be provided for natural gas or a minimum of 11
in. WC and a maximum of 13 in. WC for propane gas.
Gas Pressure Regulator
The gas pressure regulator is preset and sealed at 4
in. WC for natural gas, and 11 in. WC for propane gas.
Between the gas valve and the burners is a 1/8” pipe
plug. The pressure at this point, taken with a manome-
ter, should be about 3.7 in. WC natural gas and 10.5 in.
WC propane gas. If an adjustment is needed, remove
seal and turn adjustment screw clockwise
, to increase pressure or counter-clockwise
, to decrease pressure.
SEDIMENT
TRAP
MANUAL
SHUT-OFF
VALVE
Fig. 5: Gas Piping
CAUTION: The heater and its manual shut-off
valve must be disconnected from the gas supply
during any pressure testing of that system at
test pressures in excess of 1/2 psig (3.45 KPA).
Dissipate test pressure in the gas supply line before
reconnecting the heater and its manual shut-off
valve to gas supply line. FAILURE TO FOLLOW
THIS PROCEDURE MAY DAMAGE THE GAS
VALVE. OVER PRESSURIZED GAS VALVES ARE
NOT COVERED BY WARRANTY. The heater and
its gas connections shall be leak tested before
placing the appliance in operation. Use soapy water
for leak test. DO NOT use open flame.
CAUTION: Do not use Teflon tape on gas line
pipe thread. A pipe compound rated for use with
natural and propane gases is recommended. Apply
sparingly only on male pipe ends, leaving the two
end threads bare.

9
MANOMETER
GAS PRESSURE
TEST AT GAS
VALVE
GAS PRESSURE TEST
AT HEATER
MANUAL
SHUTOFF
VALVE
GAS PRESSURE
TEST UPSTREAM
Model
No.
1” 1-1/4” 1-1/2” 2” 2-1/2” 3” 4”
N P N P N P N P N P N P N P
926/962 15 20 45 45 110 150 360 400
1083/1125 10 15 35 35 80 120 300 300
1178/1223 25 25 60 85 220 200
1287/1336 25 20 55 75 180 170 325 560
1414/1468 20 15 45 65 150 165 300 500
1571/1631 15 15 35 50 20 125 250 400
1758/1826 15 10 30 40 100 100 225 340
2100 10 10 25 30 80 75 175 260
2500 15 20 55 55 135 160 400 600
3001 10 15 35 40 85 120 250 500
3500 10 30 30 45 80 200 400 600
4001 5 20 25 35 65 160 300 400
Natural Gas, 1000 BTU/FT3.60 Specific Gravity @ 0.5 in. WC Pressure Drop
Propane Gas, 2500 BTU/FT31.53 Specific Gravity @ 0.6 in. WC Pressure Drop
Table B: Maximum Equivalent Pipe Length
Fig. 6: Gas Pressure Test Points
Venting of Diaphragm Gas
Components
Heaters with gastrain components that have dia-
phragms in their construction are supplied with a bleed
line connection that must be connected to the outside
atmosphere as required by the National Fuel Gas
Bleed Line
Connection
Fig. 7: Bleed Line Connection
Code. Under NO circumstances shall bleed lines ter-
minate in the gas utilization equipment flue or exhaust
system.

the low temperature piping. A fireman switch included
in the time clock may be used for this purpose with
instructions not to override this sequence manually.
See wiring diagram section for electrical hookup loca-
tion of the fireman switch in the electrical circuit.
All Models With H-Bypass or CWR
These heaters must be installed using primary/sec-
ondary piping. For multiple-heater installations, use
reverse-return logic to ensure equal duty cycles. Flow
in the main line must be at least 120% of the heater
flow. See pages 16-17.
CONTROLS
Flow Switch
This dual purpose control shuts off the boiler in the
case of a pump failure or low water condition. It is
mounted and wired in series to the main gas valve.
Standard on all units except on UG models.
10
Water Connections
Location
Models 926-1223 With UG
The heater requires water flow and positive pressure
to fire and operate properly. It must therefore be
installed downstream of the discharge side of the filter
pump. A typical installation is plumbed as follows:
1. The inlet side of the filter is plumbed directly to the
discharge side of the filter pump;
2. The outlet side of the filter is then plumbed to the
inlet of the heater; and
3. The outlet of the heater is plumbed to the return
line to the pool or spa. The pump, filter and heater
are thus plumbed in series.
Heater must be located so that any water leaks will not
damage the structure of adjacent area. High-
temperature plastic pipe (CPVC) may be connected
directly into the heater, if local codes permit and if
controls operate the pump for at least fifteen minutes
after the heater is turned off.
When local codes permit the use of less than four feet
of high-temperature piping or two elbows, provisions
should be made to always shut the heater off a min-
imum of 15 minutes prior to pump shutdown in order
to carry away residual heat and prevent damage to
CAUTION: NEVER install PVC directly into heater.
Four feet of copper or high temperature pipe and
two elbows are required between the heater and the
PVC connections. See Fig. 8 below.
Fig. 8: Plumbing
NOTE: If piping is used into the heater, this piping
(copper) must be anchored or screwed into the
flange (metal) if operating pressures above 30 PSI
are encountered.
NOTE: Flow switch will not operate if flow is less
than:
Models 926-1223 60 gpm
Models 1287-1826 85 gpm
Models 2100-4001 180 gpm
Fig. 9: Flow Switch

11
Water Pressure Switch
On Models 926-1223 built with a Unitherm Governor
(UG), a water pressure switch is provided in the heater
instead of a flow switch, to shut down the gas valves in
the event the water supply to the heater is interrupted.
It is very important to verify that the switch electrically
opens and shuts off the gas valve when water flow to
the heater is interrupted.
Otherwise, rapid and severe damage to the heater
will likely occur. (The water pressure switch should
be checked and adjusted for proper operation by a
qualified service person at the time of installation and
periodically checked thereafter. Refer to pressure
switch servicing instructions on page 24).
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 (eg,
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.
WARNING: Operation of the heater without water
circulation will cause rapid and severe damage to
the heater.
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.
Unitherm Governor Operation
The patented Unitherm Governor (UG) is a thermo-
static mixing valve specifically designed to maintain
constant heater internal temperature between 105°
and 115°F despite continually changing flow rates from
the filter and changing pool temperatures. This narrow
range is needed to prevent damaging condensation on
the burners which will occur if the heater runs for any
length of time with an inlet temperature below 105°F.
It is also needed to inhibit scale formation in the tubes
by maintaining temperatures well below accelerated
scaling temperatures.
The Unitherm Governor is the default configuration on
models 926 through 1223. Where installed, it is built
into the inlet/outlet header. The larger sizes, models
1287 through 4001, do not have a UG option. Instead,
they have an externally-mounted bypass pump that is
designed to maintain the water entering the heater at
the proper temperature to prevent condensation and
scale. Thermometers are provided on the inlet and
outlet to the heater.
Companion Flange
Connections
(Models 926-1223 with UG)
DO NOT use petroleum base assembly fluids (such as
Petroleum Jelly or Lubricating Oil). If assembly lube is
required use a silicone base such as Armoral etc.
The inlet/outlet header flange accepts a 2” copper
tube as a slip connection directly into the header.
The flange is also threaded for a 2 NPT copper male
adapter.
Fig. 10: Companion Flange Connections
(Models 926–1223 with UG)

12
Raypak recommends the installation of an air bleed
vent at a suitable location (usually the highest point in
the plumbing) to remove air from the piping system.
These units should be available at your local whole-
sale supplier. Raypak does not provide this item.
Models with H-bypass are equipped with an external
pump and bypass arrangement that blends outlet
water with the inlet to increase the inlet water tempera-
ture, thereby reducing the likelihood of condensation
forming on the heat exchanger. The pump also serves
to circulate water through the heater from the main
system piping. Adjust the bypass to maintain 105ºF
inlet.
To complete the installation of the pool heater, the
poolstat needs to be installed in the main return water
line. This will ensure that the heater will be energized
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 poolstat adjacent to the main line and run
wires back to the heater. Follow the instructions listed
below to install the poolstat.
Mounting the Poolstat Control
with Front-Mounted Loop
Using Mounting Slots
For heater models:
1287, 1336, 1414, 1468, 1571, 1631, 1758, 1826,
2100, 2500, 3001, 3500, 4001.
1. Remove the poolstat control cover by removing
the two cover screws at the top. See Fig. 13 & 14.
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.
NOTE: For more detail on piping, refer to the
diagrams on pages 15, 16 & 17.
Fig. 11: Companion Flange Connections
(Models 926/962–1287/1336 with H-Bypass)
2"
Slip
Ball
Valve
3" Outlet 3" Inlet
2 H.P.
Pump
Inlet/Outlet
Header
Fig. 12: Companion Flange Connections
(Models 2100–4001)
Model No. Connection
Size
Minimum
gpm
Maximum
gpm
926–1223
with UG 2” FPT 60 100
1287–1826 2-1/2” FPT
Refer to Table D
2100–4001 3” FPT
Table C: Water Connections
Model No. Loop* Flow Rates
(gpm)
Heater Flow
Rates (gpm)
1287/1336 30–50 85
1414/1468 35–55 85
1571/1631 40–65 85
1758/1826 45–70 85
2100 50–80 180
2500 60–95 180
3001 75–115 180
3500 90–135 180
4001 100–150 180
Table D: Flow Rates
*Loop is secondary piping to heater from main system.

13
2. Lace metal strapping or clamps, (NOT PROVIDED)
through the ¾” slots on the cover and fasten
securely to pipe as shown in Fig. 15 & 16. Do not
over-tighten clamps.
Fig. 13: Poolstat Control
Fig. 14: Control Cover
Fig. 15: Hose Clamp Slots
Fig. 16: Insert Clamps
3. Remove either the left or right “knock-out” for wir-
ing on the poolstat control as shown in Fig. 17.
4. Attach appropriate conduit and connectors to the
poolstat control.
5. Attach wires to the poolstat wire terminals. See
Fig. 18.
6. Install poolstat control to the cover and fasten
cover screws.
7. Poolstat should be mounted level as shown in Fig.
19.
Fig. 17: Remove Knockout
Fig. 18: Attach Wires
Fig. 19: Mount Level

14
To adjust the temperature:
1. Both isolation valves must be fully open.
2. Adjust Bypass Valve “A” 1/2 open and Balancing
Valve “B” fully open. (See piping configuration
page 15, 16 & 17)
3. Fire your Raypak pool heater and adjust Bypass
Valve “A” to obtain a heater inlet temperature
approximately 105°F. Turning Valve A in the open
direction will raise the heater inlet temperature
and closing Valve “A” will lower the heater inlet
temperature.
4. If the heater inlet temperature remains less than
100°F and Valve “A” is fully open, leave Valve “A”
fully open and throttle Valve “B” until the heater
inlet temperature rises above 105°F.
5. The resultant heater outlet temperature should be
in the range of 120-130°F.
Fig. 22: Installation with Weld O Lets
NOTE: The drawings and instructions above show
only one of several acceptable ways of installing
the dry well into main system loop. The use of
saddle clamps and “Weld O Lets” (shown in Fig.
22) are acceptable. Follow clamp manufacturer’s
instructions.
CAUTION: The inlet water temperature must
be kept above 105°F. Changes in system flow or
valve position may require re-adjustment of the flow
settings. Check the heater bypass settings after
making adjustments. Failure to maintain an inlet
temperature above 105°F may result in damage to
the heater. Failure to comply with this instruction
voids the warranty.
Mounting Well into System
Return Loop Pipe - Front-
Mounted Loop
1. Locate and mark an area on the main system
return loop pipe where the well is always exposed
to the water circulating back from the pool. See
Fig. 20.
2. Shut off water and drain any water from the pipe
as necessary.
3. Drill a 23/32” diameter hole (½” NPT) into the pipe
as shown in Fig. 21.
4. Using a ½” NPT tap and appropriate handle,
thread the tap into the pipe.
5. Apply pipe dope as necessary to male threads
of well and insert into threaded hole. Do not
over-tighten well.
NOTE: For more detail on piping configurations for
large systems, refer to the diagrams on pages 15,
16 & 17.
HEATER
Fig. 20: Installation Location
Fig. 21: Drill Hole in Pipe for Dry Well

15
6. As the pool temperature rises to the desired tem-
perature as controlled by the Pool aquastat, small
adjustments to valves “A” and “B” will be required
for optimum performance. Heater temperatures
should be checked regularly to prevent heater
condensation. The heater inlet temperature can
be higher than 105°F without heater damage but
operating at less than 105°F inlet can cause dam-
age from condensation.
NOTE: Consult factory if target temperatures cannot
be achieved.
Piping Configurations for Raytherm Commercial Pool Heaters
Models 0926 thru 1223 with UG
INTERNAL DIVERTING
BYPASS SYSTEM (UG)
4 PIPE
DIAMETERS
MAX.

16
4 PIPE
DIAMETERS
MAX.
4 PIPE
DIAMETERS
MAX.
4 PIPE
DIAMETERS
MAX.
Models 926-1826 with H-Bypass
BLENDED WATER TEMPERATURE
(THERMOMETER AT HEATER INLET)
HEATER OUTLET TEMPERATURE
THERMOMETER
HEATER THERMOSTAT
RECOMMENDED FIELD INSTALLED
ISOLATION VALVES FOR SERVICE
TI
To
Tc
Piping Configurations for Raytherm Commercial Pool Heaters

17
BLENDED WATER TEMPERATURE
(THERMOMETER AT HEATER INLET)
HEATER OUTLET TEMPERATURE
THERMOMETER
HEATER THERMOSTAT
RECOMMENDED FIELD INSTALLED
ISOLATION VALVES FOR SERVICE
TI
To
Tc
4 PIPE
DIAMETERS
MAX.
4 PIPE
DIAMETERS
MAX.
4 PIPE
DIAMETERS
MAX.
Models 2100 thru 4001 with H-Bypass
Piping Configurations for Raytherm Commercial Pool Heaters

18
External Auxiliary Bypass
Valve (Where Required)
926-1223 Models Only
An auxiliary bypass valve should be used when flow
rates exceed 100 gpm (usually a high performance
pump size larger than two HP will exceed this flow
rate). This valve is required to complement the func-
tion of the automatic bypass valve, particularly when
starting the heater in winter or early spring when the
spa or pool temperature is below 55°F. It also serves
to eliminate needless pressure drop through the heat-
er and accompanying reduction in the flow rate to the
spa jets, etc.
Auxiliary Bypass Valve
Adjustment
To set bypass: With clean filter, adjustment is made by
feeling the inlet and outlet pipes at the heater. Outlet
pipes should be slightly warmer than inlet and comfort-
able to the touch. If pipe is hot, close bypass; if cold,
open bypass.
Models 926-1223 with UG
The heater is also equipped with a manual bypass
built into the header. This is in addition to the automat-
ic bypass valve. This may be used with flow rates up
to 100 gpm and adjusted as below.
Temperature Controls
High Limits
The pool heater is equipped with two high limits. Both
high limits, the non-adjustable auto reset high limit and
adjustable manual reset high limit are attached to the
outlet side of the in/out header.
Poolstat
The pool heater is equipped with a poolstat that is
attached to the inlet side of the in/out header to control
the pool temperature.
Fig. 23: Auxiliary Bypass Valve
NOTE: Do not use a gate valve as an auxiliary
bypass valve on any heaters.
NOTE: Sooting or liming caused by improper
bypass adjustment voids the warranty.
Bypass Valve
Open Position Closed Position
Fig. 24: Manual Bypass Valve on UG models
NOTE: To avoid water damage or scalding due to
valve operation, drain pipe must be connected to
valve outlet and run to a safe place of discharge.
Drain pipe must be the same size as the valve
discharge connection throughout its entire length
and must pitch downward from the valve. No shut-off
valve shall be installed between the relief valve and
the drain line. Valve lever should be tripped at least
once a year to ensure that waterways are clear.

19
Low Water Cutoff
Automatically shuts down burner whenever water
level drops below probe. A 3 to 5 second time delay
prevents premature lockout due to temporary condi-
tions such as power failure or air pockets. Standard
on Cal Code heaters.
High & Low Gas Pressure Switches
Pressure switches sense either high or low gas pres-
sure and automatically shut down burners if abnormal
pressures exist. Standard on Models 3001-4001.
Electrical Wiring
Electronic Ignition
The intermittent ignition device conserves energy by
automatically extinguishing the pilot when desired
temperature is reached. When additional heat is need-
ed, the pilot re-ignites electrically, eliminating the fuel
costs of maintaining a constant pilot. To ensure safe
operation, the gas valve cannot open until the pilot
relights and is confirmed.
Heater must be electrically grounded and bonded
in accordance with local codes, or, in the absence
of local codes, with the latest edition of the National
Electrical Code, ANSI/NFPA 70.
The heater draws less than 1 amp - not includ-
ing the pump power - when operating on either
120VAC or 240VAC power.
Fig. 25: Low Water Cutoff
Fig. 26: High/Low Gas Pressure Switch
Model
Without Lockout With Lockout
N P N P
926–1826 Standard N/A Optional Standard
2100–4001 N/A N/A Standard Standard
CAUTION: Label all wires prior to disconnection
when servicing controls. Wiring errors can cause
improper and dangerous operation. Verify proper
operation after servicing.
DANGER - SHOCK HAZARD - Make sure
electrical power to the heater is disconnected to avoid
potential serious injury or damage to components.
NOTE: If it is necessary to replace any of the
original wiring, it must be replaced with 105° C wire
or its equivalent.
Table E: Lockout Availability
Fig. 27: Ignition Module
NOTE: Models 2100-4001 require 240VAC power
to the pump.

20
Wiring Diagram—Models 926–1223 with UG