HTP Munchkin T50M User manual

120 Braley Rd. P.O. Box 429 East Freetown, MA 02717-0429 www.htproducts.com
LP-185 Rev. 9.9.14
Munchkin
Gas-Fired Boiler
INSTALLATION
START-UP
MAINTENANCE
PARTS
Models
T50M / T80M
80M / 140M / 199M / 399M
Heat Exchanger Bears the “ASME” Stamp
When installing models manufactured after July 7, 2008, you will notice additional selections on the control installer menu that will not
apply to this unit. DO NOT CHANGE THESE FACTORY SETTINGS. Refer to the Control Program Reference Chart within this manual
for selections that apply to this model.
This manual must be used by a qualified installer/service technician. Read all instructions in this manual before installing. Perform steps
in the given order. Failure to comply could result in substantial property damage, severe personal injury, or death.
NOTICE: HTP reserves the right to make product changes or updates without notice and will not be held liable for typographical errors
in literature.
NOTE TO CONSUMER: PLEASE KEEP ALL INSTRUCTIONS FOR FUTURE REFERENCE.

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LP-185 Rev. 9.9.14
IF THE INFORMATION IN THIS MANUAL IS NOT FOLLOWED EXACTLY, A FIRE OR EXPLOSION MAY RESULT, CAUSING
PROPERTY DAMAGE, PERSONAL INJURY, OR LOSS OF LIFE. DO NOT STORE GASOLINE OR OTHER FLAMMABLE VAPORS
AND LIQUIDS IN THE VICINITY OF THIS OR ANY OTHER BOILER.
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 provided by a qualified installer,
service agency, or the gas supplier.

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LP-185 Rev. 9.9.14
The following defined terms are used throughout this manual to bring attention to the presence of hazards of various risk
levels, or to important product information.
DANGER indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury.
WARNING indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.
CAUTION indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury.
CAUTION used without the safety alert symbol indicates a potentially hazardous situation which, if not avoided, may result in property
damage.
FOREWORD
This manual is intended to be used in conjunction with other literature provided with the MC Series Gas-Fired Boiler. This includes all
related control information. It is important that this manual, all other documents included with this system, and additional publications
including the National Fuel Gas Code, ANSI Z223.1-2002, be reviewed in their entirety before beginning any work.
Installation should be made in accordance with the regulations of the Authority Having Jurisdiction, local code authorities, and utility
companies which pertain to this type of water heating equipment.
Authority Having Jurisdiction (AHJ) –The Authority Having Jurisdiction may be a federal, state, local government, or individual such
as a fire chief, fire marshal, chief of a fire prevention bureau, labor department or health department, building official or electrical
inspector, or others having statutory authority. In some circumstances, the property owner or his/her agent assumes the role, and at
government installations, the commanding officer or departmental official may be the AHJ.
NOTE: HTP, Inc. reserves the right to modify product technical specifications and components without prior notice.
FOR THE INSTALLER
This boiler must be installed by qualified and licensed personnel. The installer should be guided by the instructions furnished with the
boiler, and with local codes and utility company requirements. In the absence of local codes, preference should be given to the National
Fuel Gas Code, ANSI Z223.1 –latest edition.
INSTALLATIONS MUST COMPLY WITH:
Local, state, provincial, and national codes, laws, regulations and ordinances.
The latest version of the National Fuel Gas Code, ANSI Z223.1, from American Gas Association Laboratories, 8501 East Pleasant
Valley Road, Cleveland, OH 44131.
In Canada –CGA No. B149 (latest version), from Canadian Gas Association Laboratories, 55 Scarsdale Road, Don Mills, Ontario,
Canada M3B 2R3. Also, Canadian Electrical Code C 22.1, from Canadian Standards Association, 5060 Spectrum Way, Suite 100,
Mississauga, Ontario, Canada L4W 5N6.
Code for the installation of Heat Producing Appliances (latest version), from American Insurance Association, 85 John Street, New
York, NY 11038.
This manual must only be used by a qualified heating installer/service technician. Read all instructions in this manual before installing.
Perform steps in the order given. Failure to comply could result in severe personal injury, death or substantial property damage.

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LP-185 Rev. 9.9.14
The latest version of the National Electrical Code, NFPA No. 70.
NOTE: The gas manifold and controls met safe lighting and other performance criteria when undergoing tests specified in ANSI
Z21.10.3 –latest edition.
The hydronic supply and return connections of these products are for installation in closed loop systems ONLY! Use of this
product in any manner other than described in this manual may result in premature product failure, substantial property damage, severe
personal injury, or death. Damage or failure of this product (or the system in which it is installed) due to unauthorized use IS NOT
COVERED BY WARRANTY.
IMPORTANT
In accordance with Section 325 (f) (3) of the Energy Policy and Conservation Act, HTP, Inc. has provided this boiler with
multiple features designed to save energy by reducing the boiler water temperature as heating load decreases.
These features include:
A modulating combustion system that adjusts firing rate based on heat demand.
Adjustment of boiler set point based on inferred heat load as determined by an outdoor sensor. The outdoor sensor
is supplied by HTP, Inc. with this boiler.
This boiler does not include a standing pilot.
This boiler is designed and shipped to assure the highest efficiency operation possible. Such high efficiency is
achieved by limiting heating circuit water temperature to 140°F when there is no anticipated heat load, based upon
the outdoor sensor and the Outdoor Reset Curve (sensor response curve) in the boiler software.
This feature may be over-ridden as described below in specific installations:
The boiler control is equipped with an outdoor sensor override for use with building management systems or in
cascaded systems (for systems with total input of 300,000 BTU/hr or greater).
See statement below for an important notice on the use of the override.
IMPORTANT
In accordance with Section 325 (f) (3) of the Energy Policy and Conservation Act, this boiler is equipped with a feature that
saves energy by reducing the boiler water temperature as the heating load decreases. This feature is equipped with an
override which is provided primarily to permit the use of an external energy management system that serves the same
function. THIS OVERRIDE MUST NOT BE USED UNLESS AT LEAST ONE OF THE FOLLOWING CONDITIONS IS TRUE:
An external energy management system is installed that reduces the boiler water temperature as the heating load
decreases.
This boiler is not used for space heating.
This boiler is part of a modular or multiple boiler system having a total input of 300,000 BTU/hr or greater.
This boiler is equipped with a tankless coil.
TABLE OF CONTENTS
PART 1 –GENERAL SAFETY INFORMATION..........................................................................................................................7
A. PRECAUTIONS..........................................................................................................................................................................7
B. IMPROPER COMBUSTION........................................................................................................................................................7
C. GAS............................................................................................................................................................................................7
D. WHEN SERVICING THE BOILER..............................................................................................................................................7
E. BOILER SYSTEM.......................................................................................................................................................................8
F. WATER CHEMISTRY*................................................................................................................................................................8
G. WINTERIZING............................................................................................................................................................................8
PART 2 –BEFORE YOU START................................................................................................................................................8
A. WHAT’S IN THE BOX .................................................................................................................................................................8
B. HOW THE BOILER OPERATES.................................................................................................................................................9
C. OPTIONAL EQUIPMENT .........................................................................................................................................................10

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LP-185 Rev. 9.9.14
PART 3 –PREPARE BOILER LOCATION ...............................................................................................................................10
A. BEFORE LOCATING THE BOILER..........................................................................................................................................10
B. LEVELING ................................................................................................................................................................................14
C. CLEARANCES FOR SERVICE ACCESS.................................................................................................................................15
D. RESIDENTIAL GARAGE, CLOSET, AND ALCOVE INSTALLATIONS....................................................................................15
E. EXHAUST VENT AND INTAKE PIPE.......................................................................................................................................15
F. PREVENT COMBUSTION AIR CONTAMINATION..................................................................................................................16
G. REMOVING AN EXISTING BOILER FROM AN EXISTING COMMON VENT SYSTEM .........................................................16
PART 4 –PREPARE BOILER...................................................................................................................................................17
A. REMOVE BOILER FROM PACKAGING...................................................................................................................................17
B. WALL MOUNTING CONSIDERATIONS...................................................................................................................................17
C. WALL MOUNTING INSTRUCTIONS........................................................................................................................................17
PART 5 –BOILER PIPING........................................................................................................................................................18
A. GENERAL PIPING INFORMATION..........................................................................................................................................18
B. RELIEF VALVE.........................................................................................................................................................................19
C. SEPARATE LOW WATER CUTOFF........................................................................................................................................19
D. BACKFLOW PREVENTER.......................................................................................................................................................20
E. SYSTEM WATER PIPING METHODS .....................................................................................................................................20
F. CIRCULATORS.........................................................................................................................................................................20
G. HYDRONIC PIPING WITH CIRCULATORS, ZONE VALVES, AND MULTIPLE BOILERS .....................................................20
H. CIRCULATOR SIZING..............................................................................................................................................................21
I. ZONING WITH ZONE VALVES..................................................................................................................................................23
J. ZONING WITH CIRCULATORS................................................................................................................................................23
K. MULTIPLE BOILERS................................................................................................................................................................23
L. FILL AND PURGE HEATING SYSTEM ....................................................................................................................................23
M. PIPING DETAILS .....................................................................................................................................................................24
PART 6 –PIPING WITH OPTIONAL VISION 1 SYSTEM.........................................................................................................31
A. VISION 1 SYSTEM PIPING......................................................................................................................................................31
B. ZONING WITH ZONE VALVES USING VISION 1....................................................................................................................31
C. ZONING WITH CIRCULATORS USING VISION 1...................................................................................................................31
D. PIPING DETAILS WITH THE VISION 1 SYSTEM....................................................................................................................32
PART 7 –VENTING, COMBUSTION AIR, AND CONDENSATE REMOVAL...........................................................................42
A. GENERAL.................................................................................................................................................................................42
B. APPROVED MATERIALS FOR EXHAUST VENT AND INTAKE PIPE ....................................................................................42
C. REQUIREMENTS FOR INSTALLATION IN CANADA..............................................................................................................43
D. EXHAUST VENT AND INTAKE PIPE LOCATION....................................................................................................................43
1. DETERMINE EXHAUST VENT LOCATION........................................................................................................................................................ 43
2. DETERMINE INTAKE PIPE LOCATION............................................................................................................................................................. 44
E. EXHAUST VENT AND INTAKE PIPE SIZING..........................................................................................................................45
G. LONGER VENT RUNS.............................................................................................................................................................45
H. EXHAUST VENT AND INTAKE PIPE INSTALLATION ............................................................................................................46

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LP-185 Rev. 9.9.14
I. DIAGRAMS FOR SIDEWALL VENTING....................................................................................................................................48
J. DIAGRAMS FOR VERTICAL VENTING....................................................................................................................................50
PART 8 –GAS PIPING..............................................................................................................................................................51
A. GAS CONNECTION .................................................................................................................................................................51
B. GAS PIPING .............................................................................................................................................................................52
C. CHECK INLET GAS PRESSURE.............................................................................................................................................52
D. GAS VALVE..............................................................................................................................................................................53
PART 9 –FIELD WIRING..........................................................................................................................................................54
A. INSTALLATION MUST COMPLY WITH: ..................................................................................................................................54
B. FIELD WIRING..........................................................................................................................................................................54
C. LINE VOLTAGE WIRING..........................................................................................................................................................54
D. THERMOSTAT.........................................................................................................................................................................54
PART 10 –FIELD WIRING –VISION 1 OPTION ......................................................................................................................57
PART 11 –START-UP PREPARATION....................................................................................................................................58
A. CHECK/CONTROL WATER CHEMISTRY...............................................................................................................................58
B. FREEZE PROTECTION (WHEN USED) ..................................................................................................................................59
C. FILL AND TEST WATER SYSTEM ..........................................................................................................................................59
D. PURGE AIR FROM WATER SYSTEM.....................................................................................................................................59
E. CHECK FOR GAS LEAKS........................................................................................................................................................60
F. CHECK THERMOSTAT CIRCUIT(S)........................................................................................................................................60
G. CHECK CONDENSATE REMOVAL.........................................................................................................................................60
H. FINAL CHECKS BEFORE STARTING BOILER.......................................................................................................................60
PART 12 –START-UP PROCEDURE.......................................................................................................................................61
A. OPERATING INSTRUCTIONS.................................................................................................................................................61
B. ADJUSTING THE SET POINT..................................................................................................................................................61
C. STATUS MENU........................................................................................................................................................................62
D. TEST MODE.............................................................................................................................................................................62
PART 13 –START-UP PROCEDURES WITH VISION 1 OPTION ...........................................................................................63
A. PROGRAMMING THE VISION I OPTION................................................................................................................................63
B. VISION 1 PROGRAM ACCESS................................................................................................................................................63
C. VISION 1 PROGRAM NAVIGATION........................................................................................................................................63
PART 14 –TROUBLESHOOTING ............................................................................................................................................65
A. ERROR CODE..........................................................................................................................................................................65
B. BOILER ERROR.......................................................................................................................................................................65
C. BOILER FAULT ........................................................................................................................................................................65
PART 15 –MAINTENANCE ......................................................................................................................................................68
A. MAINTENANCE PROCEDURES..............................................................................................................................................68
B. MAINTENANCE SCHEDULE FOR THE SERVICE TECHNICIAN ...........................................................................................68
C. COMBUSTION CHAMBER COIL CLEANING INSTRUCTIONS ..............................................................................................69
BOILER START-UP REPORT...................................................................................................................................................76
MAINTENANCE REPORT.........................................................................................................................................................76

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LP-185 Rev. 9.9.14
MAINTENANCE NOTES ........................................................................................................................................................................................ 80
HTP CUSTOMER INSTALLATION RECORD FORM ............................................................................................................................................. 81
PART 1 –GENERAL SAFETY INFORMATION
A. PRECAUTIONS
This boiler is for indoor installations only. Clearance to combustible materials: 0” top, bottom, sides and back. Front must have room for
service, 24” recommended. (A combustible door or removable panel is acceptable front clearance.) This boiler has been approved for
closet installation. Do not install this boiler directly on carpeting. Category IV vent systems only.
INSTALLER –Read all instructions in this manual before installing. Perform steps in the order given.
USER –This manual is for use only by a qualified heating installer/service technician. Refer to user’s information manual for your
reference. Have this boiler serviced/inspected by a qualified service technician annually.
FAILURE TO ADHERE TO THE GUIDELINES ON THIS PAGE AND HAVE THIS BOILER SERVICED/INSPECTED ANNUALLY
CAN RESULT IN SUBSTANTIAL PROPERTY DAMAGE, SEVERE PERSONAL INJURY, OR DEATH.
NOTE: When inquiring about service or troubleshooting, reference the model and serial numbers from the boiler rating label.
DO NOT USE THIS BOILER IF ANY PART HAS BEEN SUBMERGED IN WATER. Immediately call a qualified service technician. The
boiler MUST BE replaced if it has been submerged. Attempting to operate a boiler that has been submerged could create numerous
harmful conditions, such as a potential gas leakage causing a fire and/or explosion, or the release of mold, bacteria, or other harmful
particulates into the air. Operating a previously submerged boiler could result in property damage, severe personal injury, or death.
NOTE: Boiler damage due to flood or submersion is considered an Act of God, and IS NOT covered under product warranty.
Be sure to disconnect electrical power before opening boiler cabinet or performing service. Failure to do so could result in an electrical
shock that could result in property damage, serious personal injury, or death.
NOTE: If the boiler is exposed to the following, do not operate until all corrective steps have been made by a qualified serviceman:
1. FIRE
2. DAMAGE
3. WATER
Any claims for damage or shortage in shipment must be filed immediately against the transportation company by the consignee.
Due to the low water content of the boiler, improper sizing of the boiler with regard to heating system load will result in excessive cycling
and accelerated component failure. HTP DOES NOT warrant failures caused by improperly sized boiler applications. DO NOT oversize
the boiler to the system. Modular boiler installations greatly reduce the likelihood of boiler oversizing.
B. IMPROPER COMBUSTION
Do not obstruct combustion and ventilating air flow. Adequate air must be provided for safe operation. Failure to keep the exhaust vent
and intake pipe clear of ice, snow, or other debris could result in property damage, serious personal injury, or death.
C. GAS
Should overheating or gas supply fail to shut off, do not turn off or disconnect electrical supply to circulator. Instead, shut off the gas
supply at a location external to the boiler.
D. WHEN SERVICING THE BOILER
To avoid electric shock, disconnect electrical supply before performing maintenance.
To avoid severe burns, allow boiler to cool.

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LP-185 Rev. 9.9.14
E. BOILER SYSTEM
Do not use petroleum-based cleaning or sealing compounds in a boiler system. Gaskets and seals in the system may be
damaged. This can result in substantial property damage.
Do not use “homemade cures” or “patent medicines”. Substantial property damage, damage to boiler, and/or serious personal
injury may result.
Continual fresh make-up water will reduce boiler life. Mineral buildup reduces heat transfer, overheats the stainless steel heat
exchanger, and causes failure. Addition of oxygen by make-up water can cause internal corrosion in system components.
Leaks in the boiler or piping must be repaired at once.
If you have an old system with cast iron radiators, thoroughly flush the system (without boiler connected) to remove sediment.
The high-efficiency heat exchanger can be damaged by build-up or corrosion due to sediment.
NOTE: Damages resulting from incorrect installation or from use of products not approved by HTP, Inc. ARE NOT covered by warranty.
F. WATER CHEMISTRY*
Sodium less than 20mGL.
Water pH between 6.0 and 8.0
oMaintain water pH between 6.0 and 8.0. Check with litmus paper or have it chemically analyzed by water treatment
company.
oIf the pH differs from above, consult local water treatment company for treatment needed.
Hardness less than 7 grains
oConsult local water treatment companies for unusually hard water areas (above 7 grains hardness).
Chlorine concentration less than 100 ppm
oUsing chlorinated fresh water should be acceptable as levels are typically less than 5 ppm.
oDo not connect the boiler to directly heat swimming pool or spa water.
oDo not fill boiler or operate with water containing chlorine in excess of 100 ppm.
*NOTE: It is recommended to clean heat exchanger at least once a year to prevent lime scale buildup. To clean the heat
exchanger, follow the maintenance procedure in Part 15, Section B of this manual.
Hardness: 7 grains
Chloride levels: 100 ppm
pH levels: 6-8
TDS: 2000 ppm
Sodium: 20 mGL
G. WINTERIZING
NEVER use any toxic chemical, including automotive, standard glycol antifreeze, or ethylene glycol made for hydronic (non-potable)
systems. These chemicals can attack gaskets and seals in boilers, are poisonous if consumed, and can cause injury or death.
Consider piping and installation when determining boiler location.
To winterize the boiler, drain the entire system. Then apply air pressure to the drain valve and allow air and water to escape from the
purge valve (see piping instructions).
Once you have evacuated as much water as possible, pump non-toxic, NSF food grade propylene glycol, FDA rated as GRAS
(Generally Recognized As Safe), into the system. Consult the glycol manufacturer for specific instructions on concentration percentage
as well as freeze and burst protection methods. Check the volume and concentration of antifreeze to assure protection is adequate to
protect the entire system from freezing. When pumping, allow air and remaining water to escape from purge valve. When the stream
coming out of the purge valve matches the color of the non-toxic glycol, the system is adequately filled.
Finally, it is recommended to start the circulation pump and allow the system to circulate for at 30 minutes to completely blend any
trapped water that might be in the system with the glycol.
PART 2 –BEFORE YOU START
A. WHAT’S IN THE BOX
Also included with the boiler:
Temperature and Pressure Relief Valve
Pressure and Temperature Gauge

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LP-185 Rev. 9.9.14
Intake PVC Tee with Screens
Exhaust PVC Coupling with Screens
Installation Manual
Warranty
B. HOW THE BOILER OPERATES
Modulation Condensing Technology is an intelligent system that delivers highly efficient hydronic heating, while maximizing
efficiency by measuring the data parameters of your system.
Stainless Steel Heat Exchanger
The highly efficient and durable stainless steel heat exchanger is designed to extract the last bit of energy from flue gas before it is
exhausted.
Modulating Combustion System
Modulation during operation is based on supply temperature and desired temperature set point. The set point used for the control
depends upon the programmed central heating curve. The heating curve slope can be changed by the installer to better fit system
needs. The control monitors the system to regulate burner output during operation to match system demand. This increase in efficiency
allows for substantial fuel savings.
Gas Valve
The gas valve senses suction from the blower, allowing gas to flow only if the gas valve is energized and combustion air is flowing.
Supply Water Temperature Sensor
This sensor monitors boiler output water temperature (system outlet/supply). The control module adjusts the boiler firing rate so the
outlet/supply temperature is correct.
Return Water Temperature Sensor
This sensor monitors the return water temperature (system inlet/return). The control module reduces or increases boiler input,
depending on how close the inlet/return water temperature is to the outlet water temperature.
Temperature and Pressure Gauge
Allows the user to monitor system temperature and pressure.
Control
The integrated control system monitors inlet/return and outlet/supply water temperature and regulates fan speed to regulate the unit’s
BTU output. This allows the unit to deliver the required amount of heated energy and nothing more.
Burner
Constructed of high grade stainless steel, the burner uses pre-mixed air and gas and provides a wide range of firing rates.
Electrical Field Connections with Terminal Strips
The electrical cover plate allows access to the line voltage and low voltage terminal strips. Attach line voltage conduits to the three
holes at the right of the line voltage terminal strip for power, CH pump and DHW pump. Route low voltage wires through the opening to
the left of the low voltage terminal strip (see Field Wiring Instructions, Part 9).
Condensate Drain Connection
As this is a condensing high efficiency appliance, the unit has a condensate removal system. Condensate is nothing more than water
vapor, derived from combustion products and similar to an automobile when it is initially started. It is very important that the condensate
line slopes away from the boiler and down to a suitable inside drain.
If the condensate outlet on the boiler is lower than the drain, you must use a condensate removal pump (kit p/n 554200 available from
HTP.) In addition, local authorities may require a condensate neutralizer to neutralize the condensate. Condensate neutralizers are
made up of lime crystals, marble or phosphate chips. Neutralizers can be purchased from HTP (p/n 7450P-218).
It is also very important not to expose the condensate line to freezing temperatures or any type of blockage. Plastic tubing must be the
only material used for the condensate line. Steel, brass, copper or other materials will be subject to corrosion or deterioration. A second
vent may be necessary to prevent condensate line vacuum lock on a long horizontal run. Also, an increase in pipe size may be
necessary to allow condensate to drain properly. Support of the condensation line may be necessary to avoid blockage of the
condensate flow.
Spark Ignition
The burner flame is ignited by applying a high voltage to the system spark electrode. This causes a spark from electrode to ground.
The Vision 1 Optional System
By controlling the temperature delivered to the central heating circuits based on outside temperature, the Vision 1 System allows the
installer to take this highly efficient boiler and make it even more efficient. The Vision 1 System is a two temperature system, using one

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LP-185 Rev. 9.9.14
temperature for central heating and the other for use with an indirect water heater. This allows the user to increase the temperature
supplied to the indirect water heater to get a faster recovery by prioritizing the flow at a higher temperature than may be needed for the
central heating circuits (this requires two separate circulators). You must follow the piping, wiring, and programming instructions located
in the Vision One section of this manual.
C. OPTIONAL EQUIPMENT
Below is a list of optional equipment available from HTP:
Indirect Tank Sensor (Part # 7250P-325)
Outdoor sensor (Part # 7250P-319)
2” Stainless Steel Outside Termination Vent Kit (V500)
3” Stainless Steel Outside Termination Vent Kit (V1000)
2” PVC Concentric Vent Kit (Part # KGAVT0501CVT)
3" PVC Concentric Vent Kit (Part # KGAVT0601CVT)
3” Polypro Vent Kit (Part # 8400P-001)
3” Polypro Pipe (33’ length Part # 8400P-002, 49.5’ length Part # 8400P-003)
U.L. 353 Compliant Low Water Cut-Off Interface Kit with Manual Reset (Part # 7450P-225)
Alarm System (Part # 7350P-602) (to monitor any failure)
Condensate Pump (Part # 554200)
Condensate Neutralizer (Part # 7450P-218)
Vision 1 Outdoor Sensing System (Part # 7250P-622)
These additional options may be purchased through your HTP distributor.
PART 3 –PREPARE BOILER LOCATION
Carefully consider installation when determining boiler location. Please read the entire manual before attempting installation. Failure to
properly take factors such as boiler venting, piping, condensate removal, and wiring into account before installation could result in
wasted time, money, and possible property damage and personal injury.
A. BEFORE LOCATING THE BOILER
Incorrect ambient conditions can lead to damage to the heating system and put safe operation at risk. Ensure that the boiler installation
location adheres to the information included in this manual. Failure to do so could result in property damage, serious personal injury, or
death.
Failure of boiler or components due to incorrect operating conditions IS NOT covered by product warranty.
1. Installation Area (Mechanical Room) Operating Conditions
Ensure ambient temperatures are higher than 32oF/0oC and lower than 104oF/40oC.
Prevent the air from becoming contaminated by the products, places, and conditions listed in this manual, Part 3, Section F.
Avoid continuously high levels of humidity
Never close existing ventilation openings
The service life of the boiler’s exposed metallic surfaces, such as the casing, as well as internal surfaces, such as the heat exchanger,
are directly influenced by proximity to damp and salty marine environments. In such areas, higher concentration levels of chlorides from
sea spray coupled with relative humidity can lead to degradation of the heat exchanger and other boiler components. In these
environments, boilers must not be installed using direct vent systems which draw outdoor air for combustion. Such boilers must be
installed using room air for combustion. Indoor air will have a much lower relative humidity and, hence, potential corrosion will be
minimized.
This boiler is certified for indoor installations only. Do not install the boiler outdoors. Failure to install this boiler indoors could result in
substantial property damage, severe personal injury, or death.

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2. Check for nearby connections to:
System water piping
Venting connections
Gas supply piping
Electrical power
Condensate drain
3. Check area around boiler. Remove any combustible materials, gasoline, and other flammable liquids.
Failure to keep boiler area clear and free of combustible materials, liquids, and vapors can result in substantial property damage,
severe personal injury, or death.
4. Gas control system components must be protected from dripping water during operation and service.
5. If the boiler is to replace an existing boiler, check for and correct any existing system problems, such as:
System leaks
Location that could cause the system and boiler to freeze and leak.
Incorrectly-sized expansion tank
6. Clean and flush system when reinstalling a boiler.
NOTE: When installing in a zero clearance location, it may not be possible to read or view some product labeling. It is recommended to
make note of the boiler model and serial number.

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Figure 1 –Dimensions –T-50M / T-80M / 80M

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Figure 2 –Dimensions - 140M / 199M / 399M

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LP-185 Rev. 9.9.14
Table 1 –Specifications
Before considering location, many factors need to be addressed. Piping, Venting, and Condensation Removal are just a few of the
issues that need attention prior to the installation of the boiler. Please read the entire manual, as it could save time and money.
B. LEVELING
Figure 3 –Boiler Leveling
In order for the condensate to properly flow out of the collection system, the boiler must be installed with 1/8” per foot pitch toward the
back. The location must also support the boiler when it is full of water. The boiler comes equipped with leveling feet. Should the floor
beneath the boiler be uneven, use a wrench to adjust the feet so the boiler is pitched back at 1/8” per foot.

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C. CLEARANCES FOR SERVICE ACCESS
See Figure 4 for recommended service clearances. If you
do not provide the minimum clearances shown, it may not
be possible to service the boiler without removing it from
the space.
D. RESIDENTIAL GARAGE, CLOSET, AND
ALCOVE INSTALLATIONS
Check with your local Authority Having Jurisdiction for
requirements when installing boiler in a garage, closet, or
alcove. Please read the entire manual before attempting
installation. Failure to properly take factors such as boiler
venting, piping, condensate removal, and wiring into
account before installation could result in wasted time,
money, and possible property damage and personal
injury.
PRECAUTIONS
If the boiler is located in a residential garage, per ANSI
Z223.1:
Mount the bottom of the boiler a minimum of 18”
above the floor of the garage, to ensure the
burner and ignition devices are well off the floor.
Locate or protect the boiler so it cannot be
damaged by a moving vehicle.
Figure 4 –Required Clearances
For closet or alcove installations, a two pipe venting system must be used. Failure to follow this warning could result in substantial
property damage, severe personal injury, or death.
The space must be provided with correctly sized combustion/ventilation air openings for all other appliances located in the space with
the boiler. Do not install the boiler in an attic. Failure to comply with these warnings could result in substantial property damage, severe
personal injury, or death.
NOTE: For installations using room air for combustion, refer to the boiler venting section, Part 6 in this manual.
E. EXHAUST VENT AND INTAKE PIPE
Vents must be properly supported. Boiler exhaust and intake connections are not designed to carry heavy weight. Vent support
brackets must be within 1’ of the boiler and the balance at 4’ intervals. Boiler must be readily accessible for visual inspection for the first
3’ from the boiler.
Space must be provided with combustion/ventilation air
openings correctly sized for all other appliances located in
the same space as the boiler. The boiler cover must be
securely fastened to prevent the boiler from drawing air
form the boiler room. This is particularly important if the
boiler is in a room with other appliances. Failure to comply
with the above warnings could result in substantial
property damage, severe personal injury, or death.

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LP-185 Rev. 9.9.14
The boiler is rated ANSI Z21.13 Category IV (pressurized vent, likely to form condensate in the vent) and requires a special vent
system designed for pressurized venting.
You must also install intake piping from outdoors to the boiler flue adaptor. The resultant installation is categorized as direct vent
(sealed combustion). NOTE: To prevent combustion air contamination, see Table 2.
Exhaust and intake must terminate near each other and may be vented vertically through the roof or out a side wall. Exhaust vent and
intake piping methods are detailed in the Venting Section. Do not attempt to install the boiler using any other means. Be sure to locate
the boiler such that the exhaust vent and intake piping can be routed through the building and properly terminated. The exhaust vent
and intake piping lengths, routing and termination method must all comply with the methods and limits given in the venting section.
F. PREVENT COMBUSTION AIR CONTAMINATION
Install intake air piping for the boiler as described in the Venting section. Do not terminate exhaust in locations that can allow
contamination of intake air.
PRODUCTS TO AVOID
AREAS LIKELY TO HAVE CONTAMINANTS
Spray cans containing fluorocarbons
Dry cleaning/laundry areas and establishments
Permanent wave solutions
Swimming pools
Chlorinated waxes/cleaners
Metal fabrication plants
Chlorine-based swimming pool chemicals
Beauty shops
Calcium chloride used for thawing
Refrigeration repair shops
Sodium chloride used for water softening
Photo processing plants
Refrigerant leaks
Auto body shops
Paint or varnish removers
Plastic manufacturing plants
Hydrochloric or Muriatic acid
Furniture refinishing areas and establishments
Cements and glues
New building construction
Antistatic fabric softeners used in clothes dryers
Remodeling areas
Chlorine-type bleaches, laundry detergents, and cleaning solvents
Garages and workshops
Adhesives used to fasten building products
Table 2 - Contaminant Table
You must pipe outside air to the boiler air intake. Ensure that the intake air will not contain any of the contaminants listed in Table 2. For
example, do not pipe intake air near a swimming pool. Also, avoid areas subject to exhaust fumes from laundry facilities. These areas
always contain contaminants. Contaminated air will damage the boiler, resulting in possible substantial property damage, severe
personal injury, or death.
G. REMOVING AN EXISTING BOILER FROM AN EXISTING COMMON VENT SYSTEM
Do not install the boiler into a common vent with any other
appliance. This will cause flue gas spillage or appliance
malfunction, resulting in possible substantial property damage,
severe personal injury, or death.
Failure to follow all instructions can result in flue gas spillage and
carbon monoxide emissions, causing severe personal injury or
death.
When removing an existing boiler, follow the steps below with each appliance
remaining connected to the common venting system in operation, while other
appliances remaining connected to common venting system are not operating.
1. Seal any unused openings in the common venting system.
2. Visually inspect the venting system for proper size and horizontal pitch to
determine if there is blockage, leakage, corrosion or other deficiencies that
NOTE: DAMAGE TO THE BOILER CAUSED BY EXPOSURE TO CORROSIVE VAPORS IS NOT COVERED BY WARRANTY.
(Refer to the limited warranty for complete terms and conditions).
Figure 5

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LP-185 Rev. 9.9.14
could cause an unsafe condition.
3. If practical, close all building doors, windows and all doors between the space in which the appliance remains connected to the
common venting system located and other spaces in the building. Turn on clothes dryers and any appliances not connected to the
common venting system. Turn on any exhaust fans, such as range hoods and bathroom exhausts, at maximum speed. Do not operate
a summer exhaust fan. Close all fireplace dampers.
4. Place in operation the appliance being inspected. Follow the lighting instructions. Adjust the thermostat so the appliance will operate
continuously.
5. Test for spillage at the draft hood relief opening after 5 minutes of main burner operation. Use the flame of a match or candle or
smoke from a cigarette.
6. After it has been determined that each appliance remaining connected to common venting system properly vents when tested as
outlined, return doors, windows, exhaust fans, fireplace dampers and any other gas burning appliance to their previous condition of use.
7. Any improper operation of the common venting system should be corrected to conform to the National Fuel Gas Code, ANSI Z223.1.
When resizing any portion of the common venting system, the system should approach the minimum size as determined using the
appropriate tables in Appendix G in the National Fuel Gas Code, ANSI Z 223.1.
PART 4 –PREPARE BOILER
UNCRATING BOILER –Any claims for damage or shortage in shipment must be filed immediately against the transportation company
by the consignee.
COLD WEATHER HANDLING –If the boiler has been stored in a very cold location (BELOW 0oF) before installation, handle with care
until the plastic components come to room temperature.
A. REMOVE BOILER FROM PACKAGING
The boiler is easy to handle. Care must be taken to place it in a safe location prior to installation to prevent damage to the mechanical
connections.
B. WALL MOUNTING CONSIDERATIONS
T50M and T80M boilers may be wall mounted. Use only the wall mounting instructions included in installation envelope.
The wall must be capable of carrying the weight of the boiler and its related components. The weights of the boilers are approximately:
T50M –71 lbs.
T80M –74 lbs.
Failure to comply with above could result in substantial property damage, severe personal injury, or death.
C. WALL MOUNTING INSTRUCTIONS
It is recommended and safer to wall mount the boiler with two people. Use caution as to not drop the boiler, which could damage it and
cause property damage and/or personal injury. Verify that the boiler is securely mounted before leaving unsupervised. Failure to comply
with the above and properly mount the boiler could result in substantial property damage, severe personal injury, or death.
1. The wall must be vertically plumb and capable of carrying the weight of the boiler and its related components.
2. The building frame (studs) must be 16" on center. If not, you must use 1/2" minimum plywood 24" x 48", fastened with at least (14)
#12 x 3" (3/16" x 3") round head tapping screws to the frame of the building to provide proper support for the boiler. Alternate methods
of mounting must not be used. (ex. toggle bolts, hollow wall anchors) or any other fastener other than #12 x 3" (3/16" x 3") round head
tapping screws.
If the boiler is not vertically plumb, improper and unsatisfactory operation may occur, causing excessive condensation build-up,
nuisance fault codes, and unnecessary maintenance.

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LP-185 Rev. 9.9.14
3. Prior to lifting the boiler onto the wall, use the enclosed template to level and locate the 2 primary (#12 x 3" [3/16" x 3"]) round head
tapping screws, leaving about 1/4" between the screw head and the wall surface to allow for access to the keyway slot located in the
back of the boiler panel. It is extremely important that the line on the template is level when locating the first 2 screws. Failure to do so
will result in an uneven or out of level installation.
4. Remove the boiler cover. Locate the 2 keyway slots over the screws. Then lower the boiler onto the smallest part of the keyway slot.
5. Once the boiler is mounted on the first 2 screws, finish tightening the screws to the back panel. Then install the 6 additional screws of
the same size to the back panel holes. This will provide additional strength and support to the boiler.
PART 5 –BOILER PIPING
Failure to follow the instructions in this section WILL VOID the warranty and may result in property damage, serious injury, or death.
Plumbing of this product should only be done by a qualified, licensed plumber in accordance with all local plumbing codes. The boiler
may be connected to a storage tank to supply domestic hot water. HTP offers 60/80/119/175 gallon size storage tanks in either
stainless steel or glass-lined construction. These storage tanks can be directly connected to the boiler supply and return connection.
A. GENERAL PIPING INFORMATION
The building piping system must meet or exceed the piping requirements in this manual.
Use two wrenches when tightening water piping at boiler. Use one wrench to prevent the boiler return or supply line from turning.
Failure to prevent piping connections from turning could cause damage to boiler components.
1. The water supply should be shut off while connecting the boiler. A manual control valve must be placed on the inlet connection to the
boiler. Unions can be used on both the hot and cold water lines for future servicing and disconnection of the unit.
2. Purge the water line to remove all debris and air. Debris will damage the water boiler.
3. If the boiler is to be used as a potable water source, it must not be connected to a system that was previously used for non-potable
purposes.
4. Ensure that the water filter on the boiler is clean and installed.
5. New plumbing typically has contamination in the lines. Please flush the system before connection.
The boiler control module uses temperature sensors to provide both high limit protection and modulating temperature control. The
control module also provides low water protection by sensing the water pressure. Some codes/jurisdictions may require additional
external controls.
Never use dielectric unions or galvanized steel fittings when connecting to a stainless steel storage tank or boiler. Use only copper or
brass fittings. Teflon thread sealant must be used on all connections. All piping and components connected to the boiler must be
approved for potable water systems.
The National Standard Plumbing Code, the National Plumbing Code of Canada, and the Uniform Plumbing Code limit the pressure of
the heat transfer fluid to less than the minimum working pressure of the potable water system up to 30 psi maximum. The heat transfer
fluid must be water or other non-toxic fluid having a toxicity of Class 1, as listed in Clinical Toxicology of Commercial Products, 5th
Edition.

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LP-185 Rev. 9.9.14
B. RELIEF VALVE
The relief valve must comply with the standard for Relief Valves and Automatic Gas Shutoff Devices for Hot Water Supply Systems
(ANSI Z21.22) and/or the standard Temperature, Pressure, Temperature and Pressure Relief Valves and Vacuum Relief Valves,
CAN1-4.4, as well as all local codes. In addition, the relief valve must be rated to the maximum BTU/hr rating of the boiler.
The American National Standard (ANSI Z21.10.3) / Canadian Standard (CSA 4.3) do not require a combination temperature and
pressure relief valve for this boiler. However, a combination temperature and pressure relief valve may be required by local codes.
Connect discharge piping to safe disposal location. See the following guidelines.
To avoid water damage or scalding due to relief valve operation:
Discharge line must be connected to relief valve outlet and run to a safe place of disposal. Terminate the discharge line in a
manner that will prevent possibility of severe burns or property damage should the relief valve discharge.
Discharge line must be as short as possible and the same size as the valve discharge connection throughout its entire length.
Discharge line must pitch downward from the valve and terminate at least 6” above the floor drain, making discharge clearly
visible.
The discharge line shall terminate plain, not threaded, with a material serviceable for temperatures of 375oF or greater.
Do not pipe discharge to any location where freezing could occur.
No shutoff valve may be installed between the relief valve and boiler or in the discharge line. Do not plug or place any
obstruction in the discharge line.
Test the operation of the relief valve after filling and pressurizing the system by lifting the lever. Make sure the valve
discharges freely. If the valve fails to operate correctly, immediately replace with a new properly rated relief valve.
Test relief valve at least once annually to ensure the waterway is clear. If valve does not operate, turn the boiler “off” and call
a plumber immediately.
Take care whenever operating relief valve to avoid scalding injury or property damage.
For boilers installed with only a pressure relief valve, the separate storage vessel must have a temperature and pressure relief
valve installed. This relief valve shall comply with Relief Valves for Hot Water Supply Systems, ANSI Z21.22 / CSA4.4.
FAILURE TO COMPLY WITH THE ABOVE GUIDELINES COULD RESULT IN FAILURE OF RELIEF VALVE OPERATION,
RESULTING IN POSSIBILITY OF SUBSTANTIAL PROPERTY DAMAGE, SEVERE PERSONAL INJURY, OR DEATH.
Hot water outlet pipes can be hot to touch. Insulation must be used for hot water pipes below 36” to protect children against injuries due
to scalds.
NOTE: If a relief valve discharges periodically, this may
be due to thermal expansion in a closed water supply
system. DO NOT PLUG THE RELIEF VALVE. An
expansion tank may be required.
C. SEPARATE LOW WATER CUTOFF
A low water cutoff may be required by state and local codes, or by some insurance companies. A low water cutoff is also required if the
boiler is installed above the piping level. Check code requirements before installing the boiler.
If required:
Use an electrode probe type low water cutoff designed for hydronic installations.
APPROXIMATE TIME / TEMPERATURE RELATIONSHIPS IN SCALDS
120oF
More than 5 minutes
125oF
1 ½ to 2 minutes
130oF
About 30 seconds
135oF
About 10 seconds
140oF
Less than 5 seconds
145oF
Less than 3 seconds
150oF
About 1 ½ seconds
155oF
About 1 second
Table 3

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LP-185 Rev. 9.9.14
Install in a tee on the supply piping above the boiler.
Follow low water cutoff manufacturer’s instructions.
D. BACKFLOW PREVENTER
Use a backflow preventer specifically designed for hydronic boiler installations. This valve should be installed on the cold water fill
supply line per local codes. (See piping details at the end of this section.)
All piping methods shown in this manual use primary/secondary connection to the boiler loop. This is to avoid the possibility of noise or
actuator problems in zone valves because of the high-head boiler circulator. For other piping methods, consult your local HTP
representative or refer to separate piping details in this manual.
E. SYSTEM WATER PIPING METHODS
EXPANSION TANK AND MAKE-UP WATER
1. Ensure expansion tank size will handle boiler and system water volume and temperature. Allow 3 gallons for the boiler and its piping;
4 gallons for 399 models and piping.
Expansion tanks must be sized according to total system volume. This includes all length of pipe, all fixtures, appliances, etc. Failure to
properly size system expansion could result in wasted time, money, and possible property damage, personal injury, or death.
Undersized expansion tanks cause system water to be lost from relief valve and make-up water to be added through fill valve. Eventual
failure can result due to excessive make-up water addition. SUCH FAILURE IS NOT COVERED BY WARRANTY.
2. Expansion tank must be located as shown in Piping diagrams, or following recognized design methods. See tank manufacturer’s
instructions for details.
3. Connect the expansion tank to the air separator only if the separator is on the suction side of the circulator. Always install the system
fill connection at the same point as the expansion tank connection to the system.
4. Most chilled water systems are piped using a closed type expansion tank.
DO NOT install automatic air vents on closed-type expansion tank systems. Air must remain in the system and return to the tank to
provide its air cushion. An automatic air vent would cause air to leave the system, resulting in water-logging the expansion tank.
DIAPHRAGM (OR BLADDER) EXPANSION TANK
Always install an automatic air vent on top of the air separator to remove residual air from the system.
F. CIRCULATORS
DO NOT use the boiler circulator in any location other than the ones shown in this manual. The boiler circulator is selected to ensure
adequate flow through the boiler. Failure to comply could result in unreliable performance and nuisance shut downs from insufficient
flow.
SIZING SPACE HEAT SYSTEM PIPING
1. See Piping Details in this section. In all diagrams, the space heating system is isolated from the heating loop by the
primary/secondary connection.
2. Size the piping and components in the space heating system using recognized design methods.
G. HYDRONIC PIPING WITH CIRCULATORS, ZONE VALVES, AND MULTIPLE BOILERS
This boiler may function in a closed loop 15 psi system. A factory installed water pressure switch ensures adequate pressure in the
system. The boiler will not operate without a minimum of 10 psi water pressure. This assures you that if the system does have a leak,
the boiler will lock out (PRO on the display) before it damages the heat exchanger.
The included temperature and pressure gauge allows the user to monitor the system pressure and outlet temperature from the boiler. It
is important to note that the boiler has a minimal amount of pressure drop that must be calculated when sizing the circulators. Each
installation must also have an air elimination device that will remove air from the system.