Pentair MASTERTEMP MT125HD User manual

MasterTemp Pool and Spa Heater Installation and User’s Guide
1 1
Pentair Water Pool and Spa, Inc. USA – 1620 Hawkins Ave., Sanford, NC 27330, USA • [phone] • [phone] –
INSTALLATION AND USER’S GUIDE
MASTERTEMP™125 POOL AND SPA EURO
DO NOT store or use gasoline or other ammable vapors and liquids in the vicinity
of this or other appliances.
FOR
YOUR
SAFETY
Improper installation, adjustment,
alteration, service or maintenance
can cause property damage, personal injury or death.
Installation and service must be performed by a qualied
installer, service agency or the gas supplier.
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 re department.
MT125, EURO
MT125HD, EURO
FOR YOUR SAFETY - This product must be installed and serviced by authorized personnel, qualified in pool/spa
heater installation. Improper installation and/or operation can create carbon monoxide gas and flue gases which can
cause serious injury, property damage, or death. For indoor installations, as an additional measure of safety, Pentair
Aquatic Systems strongly recommends installation of suitable Carbon Monoxide Detectors in the vicinity of this
appliance and in any adjacent occupied spaces. Improper installation and/or operation will void the warranty.
FOR YOUR SAFETY - READ BEFORE OPERATING
If you do not follow these instructions exactly, a re or explosion may result, causing
property damage, personal injury or loss of life. For additional free copies of this
manual; call USA [phone]
• If you do not follow these instructions exactly, a fire or explosion may result, causing property damage,
personal injury or loss of life.
• Improper installation, adjustment, alteration, service or maintenance can cause property damage, personal
injury or death. Installation and service must be performed by a qualified installer, service agency or the
gas supplier.
• Do not place articles or against this appliance.
• Do not use or store flammable materials near this appliance.
• Do not spray aerosols in the vicinity of this appliance while it is in operation.
OWNER:
Retain For
Future
Reference
Pentair Water Pool and Spa, Inc. EMEA – Head Office: Industriepark, Wolfstee, Toekomstlaan 30, 2200 Herentals - Belgium.
10951 W. Los Angeles Ave., Moorpark, CA 93021, USA • [phone] • [phone]
www. pentaireurope.com - www.pentairwater.com.au - www.pentairpool.com - www.staritepool.com
FOR YOUR SAFETY
0087
1312
NOx CLASS 5
COUNTRY OF DESTINATION:
GB, BE, FR, DE
Natural Gas
Models
(G20, G25)
Propane Gas
(G31)
461078 461079
460902 460903
(240 VAC)

MasterTemp Pool and Spa Heater Installation and User’s Guide
Technical Data
| Technical Data
i
P/N 475106 Rev. D 2/2017
General Specifications
GAS TYPE:
GAS GROUP:
GAS SUPPLY PRESSURE:
TYPE OF APPLIANCE:
COUNTRY OF DESTINATION:
WARNING!
READ THE TECHNICAL INSTRUCTIONS BEFORE INSTALLING THIS APPLIANCE.
READ THE INSTALLATION AND USER’S GUIDE BEFORE LIGHTING THIS APPLIANCE.
0087
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6
0087
1312
THIS HEATER IS EQUIPPED TO BURN
OUTPUT
ALTITUDE
MINIMUM CLEARANCE FROM COMBUSTIBLE
CONSTRUCTED 15 CM REAR, 15 CM TOP
DO NOT INSTALL THIS HEATER UNDER AN OVERHANG
LESS THAN 1 METER FROM THE TOP. THE AREA UNDER
THE OVERHANG MUST BE OPEN ON THREE (3) SIDES.
APPROVED FOR INDOOR AND OUTDOOR INSTALLATIONS ELECTRICAL COMPLIANCE: IN ACCORDANCE
WITH LOCAL ELECTRICAL CODES.
THIS APPLIANCE MUST BE INSTALLED IN ACCORDANCE WITH THE EUROPEAN STANDARD INSTALLATION
CODES, AND WITH THE REQUIREMENTS OF THE AUTHORITY HAVING JURISDICTION.
REFER TO THE OPERATING INSTRUCTIONS FOR
APPROVED WATER TREATMENT.
TYPE G23
G20:
G31:
TEST POINT PRESSURE
MAX. WORKING PRESSURE
mbar
mbar
mbar
3.45 mbar
ELECTRICAL RATINGS:
VOLTS:
HERTZ:
AMPS:
12 A
APPLIANCE CATEGORY
COUNTRY OF DESTINATION
YEAR OF MANUFACTURE
MODEL NO.
SERIAL NO.
DESIGN AND MANFACTURED BY PENTAIR WATER POOL AND SPA, INC.
INPUT RATE
ORIFICE SIZE
MASTERTEMP™POOL HEATER
GAS
kW
mm
2000 m
kW
Label P/N
GB, BE, DE, FR
Hz
V
GAS SUPPLY PRESSURE:
G25:
mbar,

MasterTemp Pool and Spa Heater Installation and User’s Guide
Contents
Technical Data / Heater Identification Information (HIN) ............................................................................................ ii - iii
Code Requirements / References ............................................................................................................................. iv
Consumer Information and Safety / Warnings and Safety Instructions / General Specifications................................ v - vii
Section 1. Operations ............................................................................................................................ 1
Overview / Important Notices / Warranty Information ...................................................................................... 1
Using the Heater’s Control Panel ................................................................................................................. 2
Operating Instructions / Basic System Operation............................................................................................ 3
Basic System Operation / HSI (Hot-Surface Ignition) Lighting/Operation........................................................ 3
Start-up and Operation.................................................................................................................................... 3
Operating Instructions ..................................................................................................................................... 4
To Turn Off Gas to Appliance........................................................................................................................... 4
Safety Controls: Air Flow Switch (AFS) / Water Pressure Switch / Height Limit Devices ................................ 5
Operation of Ignition Module ........................................................................................................................... 6
Temperature Setting / Maximum Temperature Set Point ................................................................................. 6
Section 2. Installation ............................................................................................................................ 7
Heater Description................................................................................................................................................................................ 7
Sequence of Operation......................................................................................................................................................................... 7
Putting the Heater into Service............................................................................................................................................................. 8
Specifications ....................................................................................................................................................................................... 8
Plumbing Connections.......................................................................................................................................................................... 9
Valves................................................................................................................................................................................................... 9
Manual By-Pass ................................................................................................................................................................................... 9
Water Connections ............................................................................................................................................................................... 10
Below Pool Installation ......................................................................................................................................................................... 10
Gas Connections .................................................................................................................................................................................. 11
Gas Pipe Sizing ................................................................................................................................................................................................. 11
Sediment Trap/Drip Leg ...................................................................................................................................................................... 11
Testing Gas Leaks and Gas Pressure.................................................................................................................................................. 12
Gas Pressure Requirements ................................................................................................................................................................ 12
Outdoor Installation / Heater Clearances ............................................................................................................................................. 13 - 14
Indoor Venting—General Requirements / Heater Clearances / Outside Vent Removal ) .................................................................... 15- 16
Combustion Air Supply .................................................................................................................................................................... 15
Vent Installation (Indoor Installation or Outdoor Shelter) - Vertical Venting ................................................................................................. 16
Direct Air Intake Duct with 76 mm (3 in - UK) PVC Pipe (Indoor Installation) .................................................................................. 16
Horizontal or Vertical Venting - Using Single-Wall Stainless Gas Vent .......................................................................................... 17
Connecting Single-Wall Stainless Steel Vent to the Heater ............................................................................................................. 18 - 19
Corrosive Vapors and Possible Causes ............................................................................................................................................................ 20
Control Panel Indexing ......................................................................................................................................................................... 20
Final Installation Check ........................................................................................................................................................................ 20
Electrical Connections .......................................................................................................................................................................... 21
Fireman’s Switch Connection/Remote Control Connections................................................................................................................ 21 - 22
MasterTemp Wiring Diagram / Electrical Schematic Ladder Diagram ................................................................................................. 23 - 24
Section 3. Troubleshooting.................................................................................................................... 25
Initial Troubleshooting and Troubleshooting Chart............................................................................................................................... 25
Heater Will Not Fire Troubleshooting (A, B, C, D) ................................................................................................................................ 26 - 29
LED Diagnostics (AGS, AFS, HLS, PS Thermistor) ............................................................................................................................. 30 - 31
Burner / Heat Exchanger Troubleshooting ........................................................................................................................................... 32
Section 4. Maintenance Instructions.................................................................................................... 33
Care and Maintenance ......................................................................................................................................................................... 33
Pressure Relief Valve ........................................................................................................................................................................... 33
After Start-Up........................................................................................................................................................................................ 34
Spring, Fall (Autumn) and Winter Operation ....................................................................................................................................... 34
Maintaining Pool Temperature / Energy Saving Tips ........................................................................................................................... 35
Chemical Balance................................................................................................................................................................................. 35 - 36
Section 5. Replacement Parts .............................................................................................................. 37-41
ii
Contents |

MasterTemp Pool and Spa Heater Installation and User’s Guide
To identify the heater, see the data rating plate on the inner front panel of the heater. There are two designators for
each heater, one is the Model Number and the other is the Heater Identication Number (HIN).
Heater Identication Number (HIN)
The following example simplies the identication system:
1) MT : MasterTemp
2) Model Size : (125) : Input rating (Gross BTU/hr)
3) Fuel Type : (LP = Propane gas or NA = Natural gas)
4) Construction : (STD = Standard Model)
MT 125NA STD
MT = MASTERTEMP
FUEL TYPE =
CONSTRUCTION =
MODEL SIZE = BTU GROSS INPUT in 1000 of BTU / HR
H. I. N.
HEATER IDENTIFICATION NUMBER
ID DESIGNATOR FOR PENTAIR AQUATIC SYSTEMS MASTERTEMP 125 HEATER
NA = NATURAL GAS
LP = PROPANE GAS
Example:
1 2 3 4
®
STD = STANDARD MODEL
Heater Identification Information (HIN)
Heater Data Rating Plate Location
The heater data rating plate is located on the inner front panel of the heater. To access the data rating plate, unbolt and
remove the side door access panel as shown below.
Heater Data Rating Plate
Door Acess Panel
Top Panel
Door Acess Panel
| Heater Identification Information
iii
0087
1312
THIS HEATER IS EQUIPPED TO BURN
OUTPUT
ALTITUDE
MINIMUM CLEARANCE FROM COMBUSTIBLE
CONSTRUCTED 15 CM REAR, 15 CM TOP
DO NOT INSTALL THIS HEATER UNDER AN OVERHANG
LESS THAN 1 METER FROM THE TOP. THE AREA UNDER
THE OVERHANG MUST BE OPEN ON THREE (3) SIDES.
APPROVED FOR INDOOR AND OUTDOOR INSTALLATIONS ELECTRICAL COMPLIANCE: IN ACCORDANCE
WITH LOCAL ELECTRICAL CODES.
THIS APPLIANCE MUST BE INSTALLED IN ACCORDANCE WITH THE EUROPEAN STANDARD INSTALLATION
CODES, AND WITH THE REQUIREMENTS OF THE AUTHORITY HAVING JURISDICTION.
REFER TO THE OPERATING INSTRUCTIONS FOR
APPROVED WATER TREATMENT.
TYPE G23
G20:
G31:
TEST POINT PRESSURE
MAX. WORKING PRESSURE
mbar
mbar
mbar
3.45 mbar
ELECTRICAL RATINGS:
VOLTS:
HERTZ:
AMPS:
12 A
APPLIANCE CATEGORY
COUNTRY OF DESTINATION
YEAR OF MANUFACTURE
MODEL NO.
SERIAL NO.
DESIGN AND MANFACTURED BY PENTAIR WATER POOL AND SPA, INC.
INPUT RATE
ORIFICE SIZE
MASTERTEMP
™
POOL HEATER
GAS
kW
mm
2000 m
kW
Label P/N
GB, BE, DE, FR
Hz
V
GAS SUPPLY PRESSURE:
G25:
mbar,

MasterTemp Pool and Spa Heater Installation and User’s Guide
CODE REQUIREMENTS / REFERENCES
Installation must be in accordance with the code requirements:
• Manufacturer’s Installation Instructions
• Local Gas Fitting Regulations
• Municipal Building Codes
• EN 437: 2003 + A1 (2009) Test Gases - Test
pressures appliances categorizes.
• EN 60335-2-102/A1 - Household and similar
electric appliances - Safety - 2- 2012
• BS 6891 Specification for installation of
low pressure gas pipe work.
• BS5482:1 Code of practice for domestic
butane and propane gas burning
installations. Building Regulations|
Part L1.
• Local Electrical Regulations
• Any other statutory regulations
• EN 15502-1 : 2012 Gas fired heating
boilers general requirements test.
• BS 6644 : 2011 Specifications for
the installation and maintenance
of gas fired hot water boilers
between 70Kw - 1.8 mW, (2nd.
and 3rd. gas family).
Code Requirements / References | iV
IMPORTANT NOTICE:
DO NOT directly connect any external control device to this appliance, unless noted in this Installation and User’s Guide or
recommended by the manufacturer. Any installed control device not recommended by the manufacturer could violate the
Gas Safety Regulations (the installation and use), the above described regulations and the appliance warranty.
The manufacturer’s notices DO NOT supersede any legal requirements.
Gas Safety (Installation and Use) Regulations, (as amended).
It is the law that all gas appliances are installed by a competent person (e.g. a CORGI registered operative) in accordance with Regulations.
Failure to install appliances correctly could lead to prosecution. The installation of the Heater MUST also be in accordance with the
current I.E.E.. Wiring Regulations, the European Building Standards, the Bye Laws of the Local Water Undertaking, any relevant
requirements of the Local Authority, and Health and Safety document No 635, “Electricity at Work Regulations”.
Detailed recommendations are contained in the following European Standard Codes of Practice.
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MasterTemp Pool and Spa Heater Installation and User’s Guide
| Code Requirements / References
V
WARNING
The Consumer Product Safety Commission warns that carbon monoxide is an “invisible killer”. Carbon monoxide is a
colorless and odorless gas.
1. Carbon monoxide is produced by burning fuel, including natural gas and propane.
2. Proper installation, operation and maintenance of fuel-burning appliances in the home is the most important factor in
reducing carbon monoxide poisoning.
3. Be sure that fuel burning appliances such as heaters are installed by professionals according to manufacturer’s instructions
and codes.
4. Always follow the manufacturer’s directions for safe operation.
5. Have the heating system (including vents) inspected and serviced annually by a trained service technician.
6. Examine vents regularly for improper connections, visible cracks, rust or stains.
7. Installbattery-operatedcarbonmonoxidealarms.Thealarmsshouldbecertiedtotherequirementsofthemostrecent
UL, CE, IAS, CSA and IAPMO standard for carbon monoxide alarms. Test carbon monoxide alarms regularly and
replace dead batteries.
WARNING
The Consumer Product Safety Commission warns that elevated water temperature can be hazardous. See below for
water temperature guidelines before setting temperature.
1. Spa or hot tub water temperatures should never exceed 40° C. A temperature of 37° C. is considered safe for a healthy
adult. Special caution is suggested for young children. Prolonged immersion in hot water can induce hyperthermia.
2. Drinking of alcoholic beverages before or during spa or hot tub use can cause drowsiness which could lead to
unconsciousnessandsubsequentlyresultindrowning.
3. Pregnantwomenbeware!Soakinginwaterabove37°C.cancausefetaldamageduringtherstthreemonthsofpregnancy
(resulting in the birth of a brain-damaged or deformed child). Pregnant women should stick to the 37° C. maximum
rule.
4. Before entering the spa or hot tub, the user should check the water temperature with an accurate thermometer. Spa or
hot tub thermostats may error in regulating water temperatures by as much as -15° C.
5. Persons with a medical history of heart disease, circulatory problems, diabetes or blood pressure problems should obtain
their physician’s advice before using spas or hot tubs.
6. Personstakingmedicationwhichinducedrowsiness,suchastranquilizers,antihistaminesoranticoagulantsshouldnot
use spas or hot tubs.
DANGER
CARBON MONOXIDE GAS IS DEADLY – Exhaust from this pool heater contains toxic levels of carbon monoxide, a dangerous,
poisonous gas you cannot see or smell.
THE MASTERTEMP HEATER IS CLASSIFIED AS A CLASS 5 LOW NOX BOILER.
WARNING
Should overheating occur or the gas supply fail to shut off, turn off the manual gas control valve to the heater. Do not
use this heater if any part has been under water. Immediately call a qualified service technician to inspect the heater
CONSUMER INFORMATION AND SAFETY

MasterTemp Pool and Spa Heater Installation and User’s Guide
WARNINGS AND SAFETY INSTRUCTIONS
The MasterTemp pool heaters are designed and manufactured to provide many years of safe and reliable service when
installed, operated and maintained according to the information in this manual. Throughout the manual, safety warnings and
cautions are identified by the “ “ symbol. Be sure to read and comply with all of the warnings and cautions.
DANGER — CARBON MONOXIDE GAS IS DEADLY
• • READ OWNERS MANUAL COMPLETELY BEFORE OPERATING. • •
THIS PRODUCT MUST BE INSTALLED AND SERVICED BY A PROFESSIONAL SERVICE
TECHNICIAN, QUALIFIED IN POOL HEATER INSTALLATION. Some jurisdictions require
that installers be licensed. Check with your local building authority about contractor licensing
requirements. Improper installation and/or operation could create carbon monoxide gas and flue
gases which could cause serious injury or death. Improper installation and/or operation will void the
warranty.
Exhaust from this pool heater contains carbon monoxide, a dangerous, poisonous gas you
cannot see or smell. Symptoms of carbon monoxide exposure or poisoning include dizziness,
headache, nausea, weakness, sleepiness, muscular twitching, vomiting and inability to think
clearly. IF YOU EXPERIENCE ANY OF THE ABOVE SYMPTOMS, IMMEDIATELY TURN OFF
THE POOL HEATER, LEAVE THE VICINITY OF THE POOL OR SPA AND GET INTO FRESH
AIR IMMEDIATELY. THE POOL HEATER MUST BE THOROUGHLY TESTED BY A GAS
PROFESSIONAL BEFORE RESUMING OPERATION.
EXCESSIVE CARBON MONOXIDE EXPOSURE CAN CAUSE BRAIN DAMAGE OR
DEATH.
Install this pool heater far from open windows, doors, vents and other openings, see page 16 for
minimum distances.
Pentair strongly recommends that all vents, pipes and exhaust systems be initially and periodically
tested for proper operation. This testing can be accomplished by using a hand-held carbon
monoxide meter and/or by consulting with a gas professional.
Pool heaters must be used in conjunction with carbon monoxide detectors installed near the pool
heater. The carbon monoxide detectors must be periodically inspected for proper operation so as
to insure continued safety. Broken or malfunctioning carbon monoxide detectors must be replaced
immediately.
WARNING — This heater is equipped with an unconventional gas control valve that is factory set with
a manifold pressure of 1.1 ± 0.5 mbar. Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal injury or loss of life. Installation or service must
be performed by a qualified installer, service agency or the gas supplier. If this control is replaced, it
must be replaced with an identical control.
Do not attempt to adjust the gas flow by adjusting the regulator setting.
WARNING — Risk of fire or explosion from incorrect fuel use or faulty fuel conversion. Do not try to run a
heater set up for G20, G25 or G31 gas or vice versa. Only qualified service technicians should attempt
to convert heater from one fuel to the other. Do not attempt to alter the rated input or type of gas by
changing the orifice. If it is necessary to convert to a different type of gas, consult your Pentair dealer.
Serious malfunction of the burner can occur which may result in loss of life. Any additions, changes,
or conversions required in order for the appliance to satisfactorily meet the application needs must
be made by a Pentair dealer or other qualified agency using factory specified and approved parts.
The heater is available for use with G20, G25 or G31 gas only. It is not designed to operate with any
other fuels. Refer to the nameplate for the type of gas the heater is equipped to use.
• Use heater only with the fuel for which it is designed.
• If a fuel conversion is necessary, refer this work to a qualified service technician or gas supplier
before putting the heater into operation.
Warnings and Safety Instructions | vi

MasterTemp Pool and Spa Heater Installation and User’s Guide
WARNINGS AND SAFETY INSTRUCTIONS (continued)
WARNING — Risk of fire or explosion from flammable vapors. Do not store gasoline, cleaning fluids, varnishes,
paints, or other volatile flammable liquids near heater.
WARNING — Risk of explosion if unit is installed near G31 gas storage. G31 gas is heavier than air. Consult
local codes and fire protection authorities about specific installation requirements and restrictions.
Locate the heater away from propane gas storage and filling equipment as specified by the Standard
for the Storage and Handling of G31 (latest edition).
WARNING — Risk of fire. Do not place articles on, near or against the heater.
WARNING — Risk of burn hazard. To reduce the risk of injury, do not touch the side heater vent cover when
the heater is operating. Side heater vent covers are HOT and can burn when touched causing
personal injury. Do not allow children to play on or around heater or associated equipment.
THE AVERAGE TEMPERATURE OF THE HEATERS FLUE EXHAUST IS 204 DEGREES
CELSIUS (°C).
WARNING — Risk of asphyxiation if exhaust is not correctly vented. Follow venting instructions exactly
when installing heater. Do not use a draft hood with this heater, as the exhaust is under
pressure from the burner blower and a draft hood will allow exhaust fumes to blow into the room
housing the heater. The heater is supplied with an integral venting system for outdoor installation.
CAUTION — Label all wires prior to disconnection when servicing controls. Wiring errors can cause improper
and dangerous operation. Wiring errors can also destroy the control board.
• Connect heater to 240 Volt, 50 Hz., Single Phase power only.
• Verify proper operation after servicing.
• Do not allow children to play on or around heater or associated equipment.
• Never allow children to use the pool or spa without adult supervision.
• Read and follow other safety information contained in this manual prior to operating this pool heater.
GENERAL SPECIFICATIONS
NOTICE:
• Combustion air contaminated by corrosive chemical fumes can damage the heater and will void the warranty.
• The Combination Gas Control Valve on this heater differs from most appliance gas controls. If it must be replaced,
for safety reasons replace it only with an identical gas control.
• The access door panels must be in place to provide proper ventilation. Do not operate the heater for more than five (5)
minutes with the access door panels removed.
• This heater is design certified by CERTIGAZ as complying with the Standard for Gas Fired Pool Heaters, and is
intended for use in heating fresh water swimming pools or spas.
• The heater is designed for the heating of chlorine, bromine or salt system swimming pools and spas. It should NOT be
used as a space heating boiler, or general purpose water heater. The heater requires an external 240 VAC
single-phase electric power source.
• The heater should be located in an area where leakage of the heater or connections will not result in damage to the
area adjacent to the heater or to the structure. When such locations cannot be avoided, it is recommended that a
suitable drain pan, adequately drained, be installed under the heater. The pan must not restrict air flow.
• The heater may not be installed within 3.5 m (11.5 ft.) of the inside surface of a pool or spa unless it is separated by a
solid fence, wall or other permanent barrier.
Vent
Cover
vii
| Warnings and Safety Instructions

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
| 1
MasterTemp™ 125 High Performance Heater
Congratulations on your purchase of a MasterTemp™125 high performance heating system. Proper installation and
service of your new heating system and correct chemical maintenance of the water will ensure years of enjoyment. The
MasterTemp is a compact, lightweight, efcient, induced-draft, gas red high performance pool and spa heater that can
be directly connected to 63 mm (2 in) PVC pipe. The MasterTemp also comes equipped with a multifunction temperature
controller which shows, at a glance, the proper functioning of the heater. All MasterTemp heaters are designed with a
direct ignition device, HSI (hot-surface ignition), which eliminates the need for a standing pilot. The MasterTemp heater
operates on 240 VAC 50 Hz.
SPECIAL INSTRUCTIONS TO OWNER: Retain this manual for future reference. This instruction manual provides
operating instructions, installation and service information for the MasterTemp high performance heater. The information
in this manual applies to all MasterTemp models. READ AND REVIEW THIS MANUAL COMPLETELY, it is very
important that the owner/installer read and understand the section covering installation instructions, and recognize the
European Standard Codes of Practice before installing the MasterTemp. Its use will reduce service calls and chance of
injury and will lengthen product life. History and experience has shown that most heater damage is caused by improper
installation practices.
IMPORTANT NOTICES
THIS PRODUCT MUST BE INSTALLED AND SERVICED BY A PROFESSIONAL SERVICE TECHNICIAN,
QUALIFIED IN POOL HEATER INSTALLATION.
For the installer and operator of the MasterTemp pool and spa heater: The manufacturer’s warranty may be void
if, for any reason, the heater is improperly installed and/or operated. Be sure to follow the instructions set forth in
this manual. If you need more information or if you have any questions regarding to this pool heater, please contact
Pentair Water Pool and Spa, Inc. EMEA – Head Ofce: Industriepark, Wolfstee, Toekomstlaan 30, 2200 Herentals
- Belgium or Pentair Water Pool and Spa, USA – at [phone] • [phone] • [phone].
WARRANTY INFORMATION
The MasterTemp pool heater is sold with a limited factory warranty. Specic details are described on the warranty
registration card which is included with the product. Return the warranty registration card after lling in the serial
number from the rating plate inside the heater.
High standards of excellence include a policy of continuous product improvement results in your state-of-the-art heater.
We reserve the right to make improvements which change the specications of the heater without incurring an obligation
to update the current heater equipment.
These heaters are designed for the heating of chlorine, bromine or salt system swimming pools and spas or in
non-stationary installations, and should never be employed for use as space heating boilers or general purpose
water heaters. The manufacturer’s warranty may be void if, for any reason, the heater is improperly installed
and/or operated. Be sure to follow the instructions set forth in this manual.
CAUTION
OPERATING THIS HEATER CONTINUOUSLY AT WATER TEMPERATURE BELOW 20°C. WILL CAUSE
HARMFUL CONDENSATION AND WILL DAMAGE THE HEATER AND VOID THE WARRANTY. Do not use
the heater to protect pools or spas from freezing if the final maintenance temperature desired is below
20°C, as this will cause condensation related problems.
Section 1: Overview
Section 1. Overview

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
2| Section 1. Overview (Operator Control Panel)
Temperature
Up and Down
Digital Temperature
Display
System Operation
Indicator Lights
Dual Temperature
Controls
Heater "OFF"
Switch
WARNING
Risk of explosion or fire causing burns or death if safety interlocks are disabled. DO NOT attempt to operate
heater when SERVICE HEATER light is on or if blower or burner will not start. Instead, follow instructions
under “To Switch Off Gas to the Appliance,” and call a qualified service technician to repair unit.
USING THE HEATER’S CONTROL PANEL
The MasterTemp heater controls are as follows:
POOL ON Press this button to control the heater operation by the pool temperature setting.
SPA ON Press this button to control the heater operation by the spa temperature setting.
HEATER OFF Press this button to switch off the heater.
 TEMP Press this button to raise the temperature setting.
 TEMP Press this button to lower the temperature setting.
To toggle the display between degrees Centigrade (°C) and degrees Fahrenheit (°F):
1. Press the HEATER OFF button to switch the heater OFF.
2. Press TEMP or TEMP for ve (5) seconds. The display will ash once and change modes (°C to °F or
vice versa).
3. Press the HEATER OFF button to switch the heater ON.
When either the TEMP or TEMP buttons are pressed, the digital display will indicate the temperature setting. After
ve seconds, the display will return to the actual pool/spa temperature.
In addition to the digital temperature LED display, there are ve indicator LEDs:
The POOL ON light indicates that the pool water temperature is governing operation of the heater.
The SPA ON light indicates that the spa water temperature is governing operation of the heater.
The HEATING light comes on and stays on when the heater’s burner chamber is ring. This light should be on whenever
the burner is on. This light blinks when the heater is calling for heat but not ring. If this light is on but the burner fails
to come on, one of the “service” lights should come on, indicating a fault in the system.
The SERVICE SYSTEM light indicates that there is insufcient water ow to the heater. If the pump is operating, this
usually indicates that the lter and/or skimmers should be cleaned (some lters may require back-washing). If the light
remains on after the lter/skimmers have been serviced, the system should be checked by a qualied service technician.
The SERVICE HEATER light indicates a fault in the heater or its controls. If this light comes on, shut down the heater
(See “TO TURN OFF GAS TO THE APPLIANCE” on page 4), and have a qualied service technician check the system.

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
| 3
BASIC SYSTEM OPERATION
Start pump, make sure the pump is running and is primed, to close the water pressure switch and supply power
to heater. Be sure the pool and/or spa is properly lled with water. Follow the Lighting/Operating instructions below.
Section 1. Operation Instructions
Section 1: Operation Instructions
FOR YOUR SAFETY: READ BEFORE LIGHTING
STARTUP AND OPERATION
START-UP AND SHUTDOWN INSTRUCTIONS ARE ON THE LABEL ATTACHED TO THE COVER OF THE
APPLIANCE CONTROL BOX.
NOTICE: UPON INSTALLATION THE INSTALLER MUST INSTRUCT THE USER IN THE OPERATION AND
SAFETY DEVICES AND PROVIDE A COPY OF THE HEATER’S USER’S GUIDE.
BEFORE STARTUP
MASTERTEMP HSI ELECTRONIC IGNITION LIGHTING/OPERATION
If you do not follow these instructions exactly, a fire or explosion may result causing prop-
erty damage, personal injury or loss of life.
Do not attempt to light the heater if you suspect a gas leak. Lighting the heater can result in
a fire or explosion which can cause personal injury, death, and property damage.
WARNING
A. This appliance does not have a pilot. It is equipped
with an ignition device which automatically lights the
burners. Do not try to light the burners by hand.
B. BEFORE OPERATING, smell all around the appliance
area for gas. Be sure to smell next to the oor because
some gas is heavier than air and will settle on the oor.
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.
C. Use only your hand to turn the gas control on or off.
Never use tools. If you cannot change the ON/OFF
setting by hand, don’t try to repair it, call a qualied
service technician. Forced or attempted repair may result
in a re or explosion.
D. Do not use this heater if any part has been under water.
Immediately call a qualied service technician to inspect
the heater and to replace any part of the control system
and any gas control which has been under water.
E. Do not operate the pool heater unless the pool or spa is
properly lled with water.
F. Before operating the appliance for the rst time or
after it has been off for an extended time, perform the
following checklist:
1. Remove debris or other articles from inside the heater
and the area around the heater and its exhaust vent.
Make sure the ventilation openings are clear of debris
or obstruction. For installations in an enclosed space,
make sure openings for combustion and ventilation
air are unobstructed.
2. Keep heater area clear and free from combustibles,
ammable liquids and chemicals.
3. Check that all water connections are tight.
4. Water must be owing through the heater during
operation. Make sure that pool/spa is lled with water
and have pump operating. Check that water ow is
unobstructed from the appliance. When operating
for the rst time or after an extended shut-down, run
lter pump for several minutes to clear all air from
the system.
THE MASTERTEMP HEATER IS INTENDED FOR INSTALLATION WITH A METERED GAS PRESSURE REGULATOR.
WARNING! DO NOT INTERFERE WITH ANY SEALED COMPONENTS. THIS CAN ONLY BE DONE BY
A QUALIFIED SERVICE PROFESSIONAL.

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
4| Section
OPERATING INSTRUCTIONS
1. STOP! Read the safety information on (page v - vii).
2. Set both pool and spa thermostats to the lowest settings.
3. Turn off all electric power to the appliance.
4. This appliance does not have a pilot. It is equipped with an
ignition device which automatically lights the burner. Do not
try to light the burner by hand.
5. Turn off the outside external manual shut-off gas valve, see
Figure 1.
6. Wait ve (5) minutes to clear out any gas. If you then smell
gas, STOP! Follow “B” in the “Before Start-up” instructions
(page 3). If you don’t smell gas, go to the next step.
7. Turn on the outside external manual shut-off gas valve, see
Figure 1.
8. Set 3-way valves on inlet and outlet to pool or spa, as
appropriate.
9. Turn on all electric power to the appliance.
10. Press either the POOL ON or SPA ON button switch on the operating control.
11. Set the thermostat to desired setting (NOTICE: Set point must be above actual water temperature or burner will not
re). See page 2 “OPERATING THE CONTROL PANEL”.
12. The blower should come on immediately, and after about 20 seconds, the burner should re. When operating for the
rst time, the burner may not re on the rst try because of air in the gas line. If it does not re at rst, push the OFF
switch, wait ve minutes, and again push the POOL or SPA ON switch. The burner should re after about 20 seconds.
You may have to repeat this until all of the air has cleared the gas line.
13. The burner should re until the pool/spa temperature reaches the desired temperature set on the thermostat. The blower
will continue to run for about 45 seconds after the burner shuts off. If any of the safety interlocks should open during
burner operation, the burner shuts off immediately, but the blower continues to run for about 45 seconds. Should
overheating occur or the gas supply fail to shut off, turn off the manual gas control valve to the appliance.
14. If the appliance will not operate, follow the instructions below “TO TURN OFF GAS TO THE APPLIANCE”, and
call your service technician or gas supplier.
15. If the electrical power is lost while the heater is running, the heater will retain all program settings and the unit will
come back to it’s original mode and settings once the power is restored.
TO TURN OFF GAS TO APPLIANCE
1. Press the OFF button on operating control.
2. Switch off all electric power to the unit.
3. Turn off the outside external manual shut-off gas valve, see Figure 1.
Figure 1.
Manual
Shut-off
Valve
1. Operation Instructions

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
| 5
WARNING
SAFETY CONTROLS
AIR FLOW SWITCH AFS
The air ow switch, (see Figure 2), is a safety device used to insure that the
combustion air blower (fan) is operating and has been designed to monitor the
vacuum (negative) pressure within the blower housing. The air ow switch
is factory set and is connected upstream of the ignition module. The ignition
module does not operate unless the air pressure switch and all safety switches
are closed.
WATER PRESSURE SWITCH
Hazardous pressure. Do not bypass the Water Pressure Switch or render it inoper-
able.
WATER PRESSURE SWITCH
The water pressure switch, (see Figure 3). If the water ow is restricted,
the water pressure switch may prevent the burner from ring and cause the
“Service System” light to go on. If the light remains on after the lter has
been serviced, have a qualied service technician check the system.
For deck-level heater installations, the Water Pressure Switch is factory set
at 0.2 bar (3.00 psi). NOTE: See, Below Pool Level Installation instructions
on page 10. If the pressure switch is .3M (1 ft.) below or above the pool
water level, reset the switch so that it is open when the pump is off and
closed when the pump is running. Turn the star-wheel on the switch
clockwise
( ) to raise setting (heater below the pool) and counterclockwise
( ) to lower the setting (heater above the pool – see Figure 4. Test the
switch after resetting.NOTICE: When the heater is mounted more than
1.5M (5 ft.) above or 1.2M (4 ft.) below the deck level, a Pressure Switch is
no longer adequate. A Flow Switch must be installed instead.
NOTICE: Heater operation with incorrect
Pressure Switch setting may cause operation
with no water ow. Operation of the heater
without sufcient water ow may severely
damage it and will void the warranty.
HIGH LIMIT SWITCH
A “High Limit”, is a safety device that opens
the electrical circuit and shuts off the heater
based on a water temperature set point within
the “High Limit Device”. The MasterTemp
series of heaters contains two (2) high limit
devices which are located on the main inlet /
outlet header (see page 41 item 6).
Air Flow Switch Figure 2.
Water
Pressure
Switch
Figure 29.
Star Wheel
A reference scale is on
the back of pressure switch
Turn star wheel clockwise to raise
pressure set point if pressure switch is
more than 1.2 m (4 ft) below water level
Turn star wheel counterclockwise to lower
pressure set point if pressure switch is more
than 1.5 m (5 ft) above water level
Figure 30.
1.2 m (4 ft)
1.5 m (5 ft)
Figure 3.
Figure 4.
Section 1. Operation Instructions
HAZARDOUS PRESSURE. DO NOT BYPASS THE WATER
PRESSURE SWITCH OR RENDER IT INOPERABLE.

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
6| Section
Diagnostic LED
1 Flash - Air Flow Fault
2 Flashes - Flame No Call
For Heat
3 Flashes - Ignition
Lockout
Flame Current
Check Point
Figure 5.
SAFETY CONTROLS, (continued)
OPERATION OF IGNITION MODULE
The Ignition Module, (see Figure 5), is microprocessor based
and operates on 24VAC supplied by the transformer. The control
utilizes a microprocessor to continually and safely monitor,
analyze, and control the proper operation of the gas ame holder.
The module with the presence of the ame sensor, using ame
rectication, allows the heater to operate.
TEMPERATURE SETTING
The heater comes factory set at 25.6° C (78° F). for the pool mode and 37.8° C (100° F). for the spa mode. Using the up
and down arrows, you can set the pool/spa thermostats to a minimum temperature of 18.3° C (65° F.), or a maximum of
40° C (104° F). If you desire to heat only one body of water, the thermostat is capable of an off mode. As an example,
if you only wish to heat the spa and not the pool, simply depress and hold the pool down arrow, and the thermostat will
lower its setting to 18.3° C (65° F.) then go to an off mode. See below to change the heater’s factory set temperature
settings.
MAXIMUM TEMPERATURE SET POINT
1. Unbolt and remove the door panels (see Figure 6).
2. Access the control panel board on the underside of the top cover.
Locate the yellow button on the corner of the control board.
3. Push the Max. Temp. Set Point button on the back of the
control board (see Figure 7).
The following sequence should happen:
1. The unit turns on and the POOL ON light will
turn on.
2. Press the TEMP or TEMP button (on TOP of the
control panel) to set maximum pool temperature.
3. Wait up to 30 seconds; the POOL ON light will turn off
and the SPA ON light will turn on. To override the time
delay, push the Max. Temp. Set Point button again.
4. Press the TEMP or TEMP button on the control
panel and set maximum spa temperature to 40°C
(104° F) or less.
5. Wait up to 30 seconds; the SPA ON light will turn off
and the unit will shut down. To override the time delay,
push the Max. Temp. Set Point button again.
6. Reinstall the access door panels.
Door Acess Panel
Top Panel
Door Acess Panel
Figure 6.
S1
SET
M AX
S1
SET
M AX
Figure 7.
1. Operation Instructions

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
| 7
Section 2: Installation
Gas
Air
Mixer
Blower
Inlet
(Cold
Water)
Exhaust
Heating Coils
Outlet
(Mixed
Water)
Burner
Figure 8.
THISPRODUCTMUSTBEINSTALLEDANDSERVICEDBYAPROFESSIONALSERVICETECHNICIAN,QUALIFIED
IN POOL HEATER INSTALLATION. THE MASTERTEMP HEATER IS INTENDED FOR INSTALLATION WITH A
METERED GAS PRESSURE REGULATOR.
Pentair strongly recommends that all vents, pipes and exhaust systems be initially and periodically tested for
proper operation. This testing can be accomplished by using a hand-held carbon monoxide meter and/or by
consulting with a gas professional.
Pool heaters must be used in conjunction with carbon monoxide
detectors installed near the pool heater. The carbon monoxide
detectorsmustbe periodicallyinspected forproper operationso
as to insure continued safety. Broken or malfunctioning carbon
monoxide detectors must be replaced immediately. If not fitted
on the heater, the installer must installed any safety devices
according to the European Standard Codes of Practice.
NOTICE: UPON INSTALLATION THE INSTALLER MUST
INSTRUCT THE USER IN THE OPERATION AND SAFETY
DEVICES AND PROVIDE A COPY OF THE HEATER’S USER’S
GUIDE THIS MANUAL.
HEATER DESCRIPTION
Figure 8 is a diagram of the heater showing how it operates. Precisely
matched orice plates meter the air and gas into the mixer. The blower
draws the air and gas through the mixer and forces it into the burner’s
ame holder. A sealed heat exchanger surrounds the ame holder,
discharging exhaust gases out the ue.
63 mm (2 in - UK) PVC water piping connects directly to the manifold/header on the heat exchanger using 63 mm
(2 in - UK) PVC slip unions provided with the heater. The outer manifold remains cool; no heat sinks are required. A
thermal regulator and an internal bypass regulate the water ow through the heat exchanger to maintain the correct outlet
temperature. The heater operator control panel board assembly is located on top of the heater.
SEQUENCE OF OPERATION
An electronic temperature sensing thermistor in the manifold adapter inlet controls the heater operation. When the inlet
water temperature drops below the temperature set on the operating control, the burner controller supplies power to
the combustion air blower through a series of safety interlocks. The interlocks consist of:
• the pressure switch (PS), which senses that the pump is running,
• the high limit switch (HLS), which opens if the heat exchanger outlet temperature goes above 55° C (131° F), and
• the air ow switch (AFS), which senses the pressure drop across the air metering orice,
• the automatic gas shut-off (AGS) switch, which opens if the heat exchanger outlet temperature goes above 60° C
(140° F).
• the inlet temperature control switch, which opens if the inlet temperature goes above 45° C (110° F).
• the stack ue sensor (SFS), which shuts down the heater if the ue gas temperature reaches 249° C (480° F).
The air ow switch (AFS) senses the pressure drop across the air metering orice. As soon as there is sufcient air ow,
the AFS closes, closing the circuit to the hot surface igniter (HSI), which ignites the fuel mixture. On a call for heat,
the blower and HSI are energized. In about 20 seconds, the gas valve opens and ignition occurs. The HSI then switches
to a sensing mode and monitors the ame.
The heater is equipped with a digital operating control that enables the user to pre-set the desired pool and spa water
temperatures. The control enables the user to select between pool and spa heating, and features a digital display that
indicates the water temperature.
Section 2. Installation

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
8| Section
These installation instructions are designed for use by qualied personnel only, trained especially for installation of this
type of heating equipment and related components. Some states require installation and repair by licensed personnel. If
this applies in your state, be sure your contractor bears the appropriate license. See Figure 9 for Outdoor Installations.
SPECIFICATIONS
Figure 9.
(5.5")
140 mm
(21")
533 mm
(21")
533 mm
(29.43")
747 mm
(23")
584 mm
(11")
280 mm
(11")
280 mm
(17.5")
445 mm
ELECTRICAL
CONDUIT PORT
FRONT VIEWTOP VIEW
EXHAUST SIDE VIEWPLUMBING SIDE VIEW
(1.5" - UK)
50 mm
DIMENSIONS IN CENTIMETERS & INCHES
PUTTING THE HEATER INTO SERVICE
If the heater is installed below the level of the pool, or more than 0.6 meters (2 feet) above pool level, the pressure switch
setting should be adjusted. See “WATER PRESSURE SWITCH” in the “SAFETY CONTROLS Section” (page 5) and
the “CAUTION” under “BELOW POOL INSTALLATION Section” (see page 10).
Before putting the heater into service for the rst time, follow the instructions under “BEFORE START-UP” (page 3) in
the front of this manual. Check for proper operation of the heater by following the steps under, see page 4 “OPERATION
INSTRUCTIONS.”
Notice: Damage to equipment caused by improper installation or repair will void the warranty.
1. Installation

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
| 9
PUMP
FILTER
HEATER
MANUAL
BY-PASS
TO
POOL
GATE
VALVE
FROM
POOL
FROM
FILTER
Figure 10.
Table 1.
Cool water in
Warm water out
OUTLET TO POOL
INLET FROM HEATER
1. Set Manual By-Pass Valve.
2. Remove Handle.
See page 33 for Pressure Relief Valve Installations.
Figure 11.
Model Min. L/m
(GPM)
Max. L/m (GPM)
*
125 76 (20) 265 (70)
* DO NOT EXCEED THE MAXIMUM RECOMMENDED FLOW RATE FOR THE
CONNECTING PIPING.
Section 2. Installation
PLUMBING CONNECTIONS
The MasterTemp™ heater has the capability of direct PVC
water piping plumbing connections. A set of bulkhead
ttings is included with the MasterTemp to insure conformity
with Pentair’s recommended PVC plumbing procedure.
Other plumbing connections can be used. See Figure 11 for
plumbing connections.
CAUTION Before operating the heater on a
new installation, turn on the circulation pump and
bleed all the air from the filter using the air relief
valve on top of the filter. Water should flow freely
through the heater. Do not operate the heater
unless water in the pool/spa is at the proper level.
If a manual by-pass is installed, temporarily close
it to insure that all air is purged from the heater.
VALVES
When any equipment is located below the surface of the pool or spa, valves should be placed in the circulation piping
system to isolate the equipment from the pool or spa. Check valves are recommended to prevent back-siphoning. Back-
siphoning is most likely to occur when the pump stops, creating a pressure-suction differential. Do NOT sanitize the
pool by putting chlorine tablets or sticks into the skimmer(s). When the pump is off, this will cause a high concentration
of chlorine to enter the heater, which could cause corrosion damage to the heat exchanger.
CAUTION
Exercise care when installing chemical feeders so as to not allow back siphoning of chemical into the
heater, filters or pump. When chemical feeders are installed in the circulation of the piping system,
make sure the feeder outlet line is down stream of the heater, and is equipped with a positive seal
noncorrosive “Check Valve”, (P/N R172288), between the feeder and heater.
MANUAL BYPASS VALVE  WATER FLOW RATE
A bypass valve MUST be installed to regulate water ow to ensure the
ow does not exceed the maximum allowed rate of 265 L/m. After
installing the bypass valve, adjust the valve to bring the ow rate within
the acceptable range. Then remove the valve handle or lock it in place
to avoid tampering. See Figure 11.

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
10 | Section
Pool
Main
Drain
Spa
From Pool 3-Way
Valve
3-Way
Valve
3-Way
Valve
Chlorinator
Heater
Pump
Check Valve
Filter
WATER CONNECTIONS
The heater requires proper water ow and pressure for its
operation. See Figure 12 for the recommended installation.
The lter pump discharges to the lter, the lter discharges
to the heater, and the heater discharges directly to the pool
or spa.
A manual bypass valve MUST be installed across the heater
when the pump ow exceeds 265 L/m (120 GPM). See
“WATER FLOW RATE” on page 9 - Table 1 for setting of
the manual by-pass valve.
Make sure that the outlet plumbing from the heater contains
no shut-off valves or other ow restrictions that could prevent
ow through the heater (except for below pool as noted below,
or winterizing valves where needed). To switch ow between
the pool and spa, use a diverter valve. Do not use any valve
that can shut off the ow. Do not use a shut-off valve to isolate
the heater unless it is below the level of the pool or spa.
Install the chemical feeder downstream of the heater. Install
a chemical resistant one-way check valve between the heater and the chemical feeder to prevent back-siphoning through
the heater when the pump is off.
NOTICE: If the heater is plumbed in backwards, it will cycle continuously. Make sure piping from lter is not reversed
when installing heater.
Connect the heater directly to 50 mm (1.5 in - UK) PVC pipe, using the integral unions provided. Heat sinks are not
required. The low thermal mass of the heater will prevent overheating of the piping connected to the pump even if the
heater shuts down unexpectedly. Occasionally a two-speed pump will not develop enough pressure on the low speed to
operate the heater. In this case, run the pump at high speed only to operate the heater. If this does not solve the problem,
do not try to run the heater. Instead, correct the installation.
Do not operate the heater while an automatic pool cleaner is also operating. If the circulation pump suction is plugged
(for example by leaves), there may not be adequate ow to the heater. Do not rely on the pressure switch in this case.
If European Standard Codes of Practice require the installation of a pressure relief valve (PRV), see page 33 for
“PRESSURE RELIEF VALVE INSTRUCTIONS”.
BELOW POOL INSTALLATION
If the heater is below water level, the pressure switch must be adjusted. This adjustment must be done by a qualied
service technician. See following CAUTION before installation.
CAUTION
BELOW OR ABOVE POOL INSTALLATION
The Water Pressure Relief Valve Switch is set in the factory at 0.20 bar (3.00 psi). This setting is for a
heater installed at pool level. If the heater is to be installed more than 0.3 m above or below, the water
pressure switch must be adjusted by a qualified service technician. See page 3, Figure 5.
FLOW SWITCH INSTALLATION
If the heater is installed more than 1.5 m above the pool or more than 1.2 m below the pool level, you will
be beyond the limits of the pressure switch and a flow switch must be installed. Locate and install the
flow switch externally on the outlet piping from the heater, as close as possible to the heater. Connect
the flow switch wires in place of the water pressure switch wires.
Figure 12.
2. Installation

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
| 11
GAS CONNECTIONS
GAS LINE INSTALLATIONS
The gas supply must be installed in accordance with the European Standard Codes of Practice for gas installation as applicable
and all applicable local codes.
THEMASTERTEMPHEATERISINTENDEDFORINSTALLATIONWITHAMETEREDGASPRESSUREREGULATOR.
Before installing the gas line, be sure to check which gas the heater has been designed to burn. This is important because
different types of gas require different gas pipe sizes. The rating plate on the heater will indicate which gas the heater is designed
to burn. Table 2 below shows the recommended gas inlet pipe sizes required for the distance from the gas meter to the heater.
The table is for G20 and G25 at a specic gravity of .65 and G31 at a specic gravity of 1.55.
When sizing gas lines, calculate 0.9 additional meters of straight pipe for every elbow used. When installing the gas line, avoid
getting dirt, grease or other foreign material in the pipe as this may cause damage to the gas valve, which may result in heater failure.
The gas meter should be checked to make sure that it will supply enough gas to the heater and any other appliances that may
be used on the same meter. Insufcient gas supply will cause the heater to operate below its designed performance or not at all.
The gas line from the meter will usually be of a larger size than the gas valve supplied with the heater. Therefore a reduction
of the connecting gas pipe will be necessary. Make this reduction as close to the heater as possible. If the gas pressure is not
adjusted to the correct working pressure, the heater will be over gassed and cause serious damage within minutes. This damage
is not covered under the heater warranty.
Install a manual shut-off valve that conforms with European Standard Codes of Practice, and a sediment trap/drip leg and
union located outside the heater panels, see Figure 13. Do not use a restrictive gas cock.
The heater and any other gas appliances must be disconnected from the gas supply piping system during any pressure testing on
that system, (greater than 6.0 kPa). The heater and its gas connection must be leak tested before placing the heater in operation.
Do not use ame to test the gas line. Use soapy water or another nonammable method.
NOTE
A manual main shut-off valve must be installed externally to the heater.
WARNING
DO NOT INSTALL THE GAS LINE UNION INSIDE THE HEATER CABINET. THIS WILL VOID YOUR
WARRANTY.
GAS PIPE SIZING
SEDIMENT TRAP/DRIP LEG
Install a sediment trap/drip leg and union located outside the heater panels in accordance with European Standard Codes
of Practice requirements. Do not use a restrictive gas cock. The sediment trap/drip leg shall be either a tee tting with
a capped nipple in the bottom outlet which can be removed for cleaning, as illustrated in Figure 14, or an other device
recognized as an effective sediment trap/drip leg. All gas piping should be tested after installation in accordance with
local codes.
Figure 13.
Manual
Shut-off
Valve
Sediment
Trap/Drip Leg
Union
At least 23 cm (9")
At least 8 cm (3")
2.54 cm (1") Dia. or larger
(See "Recommended
Pipe Sizes" Chart
)
45-60 cm x 3/4 in
(18–24" of 3/4")
Gas line from
Valve
Bell
Reducer
Table 2.
Heater Size Distance from the Meter
0 to 15 m 16 to 30 m 31 to 60 m
125 25 mm 32 mm 32 mm
Section 2. Installation

MasterTemp 125 Pool and Spa Heater Installation and User’s Guide
12 | Section
THE MASTERTEMP HEATER IS INTENDED FOR INSTALLATION WITH A METERED GAS PRESSURE REGULATOR. Before
operating the heater, the heater and its gas connections must be leak tested. Do NOT use an open ame to test for leaks.
Test all gas connections for leaks with soapy water.
The gas valve must be completely disconnected from the gas supply piping system during any pressure testing of that
system at test pressures in excess of 6.0 kPa (60 mbar).
TESTING THE GAS PRESSURE THROUGH THE COMBINATION GAS CONTROL VALVE
WARNING
Risk of fire and explosion. Alteration, service, or maintenance of the Combination Gas Control Valve can
lead to fire or explosion, causing loss of life, personal injury, and/or property damage. DO NOT ATTEMPT
TO ADJUST THE GAS CONTROL VALVE.
These instructions are for the use of qualified service technicians only!
1. Shut off the gas supply to the heater.
2. Loosen the small screw inside the pressure tap as shown in Figure 14.
3. Connect the manometer hose.
4. Open the gas supply to the heater.
5. Turn on the heater.
6. Take the gas pressure reading.
7. Turn off the heater.
8. Shut off the gas supply to the heater.
9. Disconnect the manometer hose.
10. Tighten the small screw inside the pressure tap.
11. Open the gas supply to the heater.
12 Verify that the seal connection in the pressure tap is closed by testing for
leaks with soapy water.
Note: If the pressure reading is out of range, (see Table 3), regulate the incoming
gas pressure.
TESTING GAS LEAKS AND GAS PRESSURE
Table 3.
Description Type Gas Supply Pressure
Natural Gas
2H; 2E+; 2N; 2Es, 2Ei;
2ELL
(G20/G25)
20-25 mbar
Propane Gas 3P (G31) 37 mbar
NOTE:THEMINIMUMVALUEAPPROVEDFORINPUTADJUSTMENT.DONOTEXCEEDTHEMAXIMUMSUPPLYPRESSURE.All readings must be taken while heater is operating. Any adjustments or readings made while heater is off will
result in performance problems.
Lightly loosen the
small screw inside the pressure tap,
and attach/connect the manometer hose.
Figure 14.
INLET GAS PRESSURE REQUIREMENTS
This appliance is equipped with an unconventional gas control valve that is factory set with a manifold pressure of
1.1 ± 0.5 mbar. Installation or service must be performed by a qualied installer, service agency, or the gas supplier. If this
control valve is replaced, it must be replaced with an identical gas control. The combination gas valve incorporates dual
shut-off valves and a negative-pressure regulator. For proper operation, the regulated pressure at the outlet manifold of the
valve must be 1.1 ± 0.5 mbar below the reference pressure at the blower mixer inlet, and the gas valve ‘VENT’ tap must
be connected to the end cap air orice as shown in Figure 14. DO NOT attempt to adjust the gas input by adjusting the
regulator setting. The correct gas regulator setting is required to maintain proper combustion and must NOT be
altered.
2. Installation