HTP MODCON1000 Installation manual

120 Braley Rd. P.O. Box 429 East Freetown, MA 02717 www.htproducts.com
LP- 428 REV. 9.2.14
Mod Con
INSTALLATION
START-UP
MAINTENANCE
PARTS
Models
1000 / 1700*
*Boilers with a Suffix of HL Equipped with High and Low Gas
Pressure Switches
THIS MANUAL IS FOR USE WITH REV. 1 MOD CON 1000 and 1700 BOILERS
MANUFACTURED AFTER AUGUST 13, 2013
Heat Exchanger Bears the ASME “H” Stamp
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.
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 substantial property damage, severe personal injury, or death.

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LP- 428 REV. 9.2.14
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 APPLIANCE.
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- 428 REV. 9.2.14
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.
NOTICE
NOTICE is used to address practices not related to personal injury.
FOREWORD
This manual is intended to be used in conjunction with other literature provided with the appliance. 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 appliance 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 Z223.1-2002.
INSTALLATIONS MUST COMPLY WITH:
Authority Having Jurisdiction, 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.
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 substantial property damage, severe personal injury, or death.

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LP- 428 REV. 9.2.14
Code for the Installation of Heat Producing Appliances (latest version), from American Insurance Association, 85 John Street, New
York, NY 11038.
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 the boiler underwent tests specified in
ANSI Z21.13 –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.
NOTICE
The CSD-1 ASME Code, Section CW-400 requires that hot water heating and supply boilers have a) a UL 353 temperature control
device, b) at least one (1) temperature-actuated control to shut off the fuel supply when system water reaches a preset operating
temperature, c) a high temperature limit control that prevents the water temperature from exceeding the maximum allowable
temperature by causing a safety shutdown and lockout, and d) its own sensing element and operating switch.
The temperature control system integrated into the 926 control provided with this heating appliance complies with the requirements of
CSD-1 Section CW-400 as a temperature operation control. The control monitors the temperature difference between the inlet and the
outlet sensor, which is affected by boiler water flow. If this temperature difference exceeds 55°F (typically because of low water flow or
very low heat load), the control will reduce the maximum fan speed. If the temperature difference exceeds 60°F, the control will
effectively sense there is little or no water flow or heat load and shut the boiler down. The controller will restart automatically once the
temperature difference has dropped below 55°F and the minimum off time (anti-cycle time) has expired. In addition, if the control
senses that the outlet water temperature has reached 210°F, the boiler is put into a hard lockout and requires manual reset to restart.
TABLE OF CONTENTS
PART 1 –GENERAL SAFETY INFORMATION..........................................................................................................................7
A. PRECAUTIONS..........................................................................................................................................................................7
B. GAS ............................................................................................................................................................................................7
C. IMPROPER COMBUSTION .......................................................................................................................................................7
D. WHEN SERVICING THE BOILER..............................................................................................................................................7
E. BOILER OPERATION.................................................................................................................................................................8
F. BOILER WATER.........................................................................................................................................................................8
G. FREEZE PROTECTION.............................................................................................................................................................8
PART 2 –BEFORE YOU START................................................................................................................................................8
A. WHAT’S IN THE BOX .................................................................................................................................................................8
B. HOW BOILER OPERATES.........................................................................................................................................................8
C. OPTIONAL EQUIPMENT ...........................................................................................................................................................9
PART 3 –PREPARE BOILER LOCATION ...............................................................................................................................10
A. BEFORE LOCATING THE BOILER..........................................................................................................................................10
B. FLOORING...............................................................................................................................................................................11
C. LEVELING AND DIMENSIONS................................................................................................................................................11
D. CLEARANCES FOR SERVICE ACCESS.................................................................................................................................12
E. EXHAUST VENT AND INTAKE PIPE.......................................................................................................................................13
1. DIRECT VENT INSTALLATION OF EXHAUST VENT AND INTAKE PIPE................................................................................13
2. INDOOR COMBUSTION AIR INSTALLATION IN CONFINED OR UNCONFINED SPACE.......................................................14

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LP- 428 REV. 9.2.14
F. PREVENT COMBUSTION AIR CONTAMINATION..................................................................................................................14
G. REMOVING A BOILER FROM A COMMON VENT SYSTEM..................................................................................................15
H. UNCRATING AND MOVING BOILER ......................................................................................................................................15
PART 4 –BOILER PIPING........................................................................................................................................................15
A. GENERAL PIPING INFORMATION..........................................................................................................................................16
B. RELIEF VALVE.........................................................................................................................................................................16
C. BACKFLOW PREVENTER.......................................................................................................................................................16
D. SYSTEM WATER PIPING METHODS.....................................................................................................................................17
E. CIRCULATORS ........................................................................................................................................................................17
F. HYDRONIC PIPING WITH CIRCULATORS, ZONE VALVES, AND MULTIPLE BOILERS......................................................17
G. CIRCULATOR SIZING .............................................................................................................................................................18
H. FILL AND PURGE HEATING SYSTEM....................................................................................................................................20
I. FREEZE PROTECTION FLUIDS...............................................................................................................................................20
J. ZONING WITH ZONE VALVES.................................................................................................................................................21
K. ZONING WITH CIRCULATORS ...............................................................................................................................................21
L. MULTIPLE BOILERS ................................................................................................................................................................21
M. BOILER PIPING DETAILS .......................................................................................................................................................22
PART 5 –VENTING, COMBUSTION AIR AND CONDENSATE REMOVAL............................................................................26
A. GENERAL.................................................................................................................................................................................26
B. APPROVED MATERIALS FOR EXHAUST VENT AND INTAKE PIPE ....................................................................................26
D. REQUIREMENTS FOR INSTALLATION IN CANADA..............................................................................................................27
E. EXHAUST VENT AND INTAKE PIPE LOCATION....................................................................................................................28
F. EXHAUST VENT AND INTAKE PIPE SIZING ..........................................................................................................................31
G. EXHAUST VENT AND INTAKE PIPE INSTALLATION ............................................................................................................31
H. BOILER REMOVAL FROM A COMMON VENT SYSTEM .......................................................................................................32
I. VENTING DRAWINGS...............................................................................................................................................................32
1. DIRECT VENT INSTALLATION OF EXHAUST VENT AND INTAKE PIPE................................................................................32
2. ROOM AIR, INDOOR COMBUSTION, AND VENTILATION AIR INSTALLATION REQUIREMENTS.......................................36
PART 6 –GAS PIPING..............................................................................................................................................................37
A. GAS CONNECTION .................................................................................................................................................................37
B. GAS PIPING .............................................................................................................................................................................38
C. GAS TABLE..............................................................................................................................................................................38
D. CHECK INLET GAS PRESSURE.............................................................................................................................................39
E. GAS VALVE..............................................................................................................................................................................40
PART 7 –FIELD WIRING..........................................................................................................................................................42
A. INSTALLATION MUST COMPLY WITH:..................................................................................................................................42
B. FIELD WIRING..........................................................................................................................................................................42
C. LINE VOLTAGE WIRING FOR STANDARD BOILER ..............................................................................................................42
D. ALARM CONNECTIONS (TOP BOILER CONNECTION)........................................................................................................42
E. LOW VOLTAGE CONNECTIONS.............................................................................................................................................43
F. THERMOSTAT..........................................................................................................................................................................43

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LP- 428 REV. 9.2.14
G. OUTDOOR SENSOR...............................................................................................................................................................43
H. INDIRECT SENSOR (TOP BOILER CONNECTION)...............................................................................................................43
I. OPTIONAL 0-10 VOLT BUILDING CONTROL SIGNAL ............................................................................................................43
J. OPTIONAL HIGH GAS PRESSURE SWITCH ..........................................................................................................................44
K. OPTIONAL LOW GAS PRESSURE SWITCH ..........................................................................................................................44
L. OPTIONAL FLOW SWITCH......................................................................................................................................................44
M. OPTIONAL UL353 LOW WATER CUT-OFF INTERFACE KIT................................................................................................44
N. WIRING OF THE CASCADE SYSTEM COMMUNICATION BUS............................................................................................45
PART 8 –START-UP PREPARATION......................................................................................................................................49
A. CHECK / CONTROL WATER CHEMISTRY.............................................................................................................................49
B. FREEZE PROTECTION (WHEN USED) ..................................................................................................................................50
C. FILL AND TEST WATER SYSTEM ..........................................................................................................................................50
D. PURGE AIR FROM WATER SYSTEM.....................................................................................................................................50
E. CHECK FOR GAS LEAKS........................................................................................................................................................51
F. CHECK THERMOSTAT CIRCUIT(S)........................................................................................................................................51
G. CONDENSATE REMOVAL ......................................................................................................................................................51
H. FINAL CHECKS BEFORE STARTING BOILER.......................................................................................................................52
I. CASCADE SYSTEM –MOD CON 1000 AND 1700 MODELS...................................................................................................52
PART 9 –START-UP PROCEDURE.........................................................................................................................................53
A. CONTROL OVERVIEW ............................................................................................................................................................53
B. NAVIGATION OF THE DISPLAY..............................................................................................................................................53
C. OPERATING INSTRUCTIONS.................................................................................................................................................54
D. PROGRAMMING BOILER SETTINGS.....................................................................................................................................54
E. PROGRAMMING THE SYSTEM SETTING..............................................................................................................................55
F. SYSTEM SETTING PROGRAM NAVIGATION.........................................................................................................................55
G. RESETTING THE MAINTENANCE SCHEDULE......................................................................................................................57
PART 10 –START-UP PROCEDURES FOR INSTALLER.......................................................................................................58
A. BOILER CONTROL STATUS MENU........................................................................................................................................58
B. BOTTOM BOILER (MASTER) MENU ONLY............................................................................................................................60
C. BOILER TEST MODE...............................................................................................................................................................60
PART 11 –SHUTDOWN............................................................................................................................................................61
A. SHUTDOWN PROCEDURE.....................................................................................................................................................61
B. VACATION PROCEDURE........................................................................................................................................................61
C. FAILURE TO OPERATE...........................................................................................................................................................61
PART 12 –TROUBLESHOOTING ............................................................................................................................................61
A. BOILER ERROR CODE............................................................................................................................................................61
B. BOILER ERROR.......................................................................................................................................................................61
C. BOILER FAULT ........................................................................................................................................................................62
D. USER INTERFACE DISPLAY ..................................................................................................................................................62
PART 13 –MAINTENANCE ......................................................................................................................................................67
A. MAINTENANCE PROCEDURES..............................................................................................................................................67

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B. COMBUSTION CHAMBER COIL CLEANING INSTRUCTIONS FOR HEATER ......................................................................68
BOILER START-UP REPORT...................................................................................................................................................76
MAINTENANCE REPORT.........................................................................................................................................................76
MAINTENANCE NOTES..................................................................................................................................................................80
HTP CUSTOMER INSTALLATION RECORD FORM......................................................................................................................81
PART 1 –GENERAL SAFETY INFORMATION
A. PRECAUTIONS
This appliance 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 appliance has been
approved for closet installation. Do not install this appliance directly on carpeting. This appliance may be installed on combustible
flooring. For use with 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.
DO NOT USE THIS APPLIANCE IF ANY PART HAS BEEN SUBMERGED IN WATER. Immediately call a qualified service technician.
The appliance MUST BE replaced if it has been submerged. Attempting to operate an appliance 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 appliance could result in property damage, severe personal injury,
or death.
NOTE: Appliance damage due to flood or submersion is considered an Act of God, and IS NOT covered under product warranty.
NOTE: If the boiler is exposed to the following, do not operate until all corrective steps have been made by a qualified serviceman:
FIRE
DAMAGE
WATER
Any claims for damage or shortage in shipment must be filed immediately against the transportation company by the consignee.
Due to low water content of the boiler, improperly sizing the boiler in regard to heating system load will result in excessive boiler 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. GAS
Should overheating occur or gas supply fail to shut off, do not turn off or disconnect electrical supply to the circulator. Instead, shut off
the gas supply at a location external to the appliance.
C. IMPROPER COMBUSTION
D. WHEN SERVICING THE BOILER
To avoid electric shock, disconnect electrical supply before performing maintenance.
Do not obstruct the flow of combustion and ventilating air. 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.

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LP- 428 REV. 9.2.14
To avoid severe burns, allow boiler to cool before servicing.
E. BOILER OPERATION
Do not block flow of combustion or ventilation air to boiler.
Should overheating occur 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 appliance.
Do not use this boiler if any part has been under water. Immediately
call a qualified service technician to inspect the boiler and replace
any part of the control system and any gas control that has been
under water.
F. BOILER WATER
Do not use petroleum-based cleaning or sealing compounds in a
boiler system. These products may damage gaskets and seals in the
system. This can result in substantial property damage.
Do not use “homemade cures” or “boiler 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.
G. FREEZE PROTECTION
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 water boilers, are poisonous if consumed, and can cause injury or death.
Consider piping and installation when determining boiler location.
NOTE: Damages resulting from incorrect installation or from use of products not approved by HTP, Inc. ARE NOT covered by warranty.
PART 2 –BEFORE YOU START
A. WHAT’S IN THE BOX
Also included with the boiler:
Pressure and Temperature Gauge
Outdoor Sensor
Installation Manual
Warranty
CSD-1 Form
H-3 Data Sheet
B. HOW BOILER OPERATES
Mod Con boilers are designed to meet the needs of the most challenging new and retrofit installations. Mod Con 1000 and 1700 models
incorporate two individual heating systems that are piped, wired, and programmed to work as one, providing built-in system redundancy
and maximum turndown and efficiency. Outlined below are features of the system and how each operates.
Stainless Steel Heat Exchanger - The highly efficient stainless steel heat exchanger is designed to use the cold return water from the
system and extract the last bit of heat before it is exhausted.
Modulating Combustion System - The combustion system will modulate the output of the burner during operation to match the
system demand and achieve the control set point while in operation. The set point can change by internal or external signals which
enhance the overall performance of the system.

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LP- 428 REV. 9.2.14
Control –The integrated control system monitors the system and regulates fan speed, controlling the output of each boiler and staging
the individual heating circuits to maximize overall efficiency. This allows the Mod Con to deliver only the amount of heat energy required
and nothing more. The system can be further enhanced by installing with an indirect water heater to provide domestic hot water.
The control can regulate the output of multiple boilers through its cascade system function. The cascade system is capable of
connecting up to eight boilers together in such a way that they function as one boiler system. This allows for greater turn down ratios
and provides systematic control of the multiple boilers in an installation to minimize downtime and maximize efficiency.
The cascade system works by establishing one boiler as the master and the other connected boilers as followers. The master boiler
requires a cascade system sensor and a cascade pump in addition to its own boiler pump. Each of the follower boilers has an individual
pump.
System Display and Operational LED Light Indicators –The display allows the user to change the system parameters and monitor
system outputs.
Gas Valve –Senses suction from the blower, allowing gas to flow only if powered and combustion air is flowing.
Integrated Venturi (1000 Models) or Swirl Plate (1700 Models) –Controls air and gas flow into the burner.
Burner –Constructed of high grade stainless steel, the burner uses premixed air and gas fuel to provide a wide range of firing rates.
Spark Ignition –The burner is ignited by applying high voltage through the system spark electrode. This causes the spark from the
electrode to ignite mixed gas from the burner.
Supply Water Temperature Sensor –This sensor monitors the boiler outlet water temperature (System Supply). The control adjusts
the boiler firing rate so the supply temperature will match the boiler set point.
Return Water Temperature Sensor –This sensor monitors the boiler return water temperature (System Return).
System Sensor –This sensor is mounted in the boiler common piping and monitors the water temperature of the outlet of both boilers
simultaneously. The master boiler uses this sensor as its primary feedback to control the outlet water temperature of a cascaded boiler
system.
Temperature and Pressure Gauge –Allows the user to monitor system temperature and pressure.
Electrical field connections with terminal strips –The electrical cover allows easy access to the line voltage and low voltage
terminals strips which are clearly marked to facilitate wiring of the boiler.
Condensation Collection System –This boiler is a high efficiency appliance, therefore the boiler will produce condensate. The
collection system has a float switch which monitors the condensation level and prevents condensation from backing up into the
combustion system. Inside the collection system there is a built in trap which seals the combustion system from the connected drain.
This condensate should be neutralized to avoid damage to the drainage system or piping.
Flow Protection –The optional flow switch is designed to protect the boiler in the event of low flow conditions. The boiler control will
also monitor flow through the heat exchanger by monitoring the return and supply sensors and will shut down the burner before
overheating occurs.
Outdoor Sensor –This sensor monitors outdoor temperature. Data from this sensor is monitored by the control, which adjusts the unit
set point to provide greater efficiency.
Indirect Tank Sensor (optional) –Monitors storage tank temperature.
C. OPTIONAL EQUIPMENT
Below is a list of optional equipment available from HTP. These additional options may be purchased through your HTP distributor.
Remote System Sensor (Part # 7250P-324)
Indirect Tank Sensor (Part # 7250P-325)
6” Stainless Steel Outside Termination Vent Kit (V3000)
High and Low Gas Pressure Switch Kit with Manual Reset (Part # 7350P-600) (Two (2) are required)
U.L. 353 Compliant Low Water Cut-Off Interface Kit with Manual Reset (Part # 7350P-601) (Two (2) are required)
Alarm System (Part # 7350P-602) (to monitor any failure) (Top Boiler Only)
PC Connection Kit (Part # 7250P-320)
Condensate Neutralizer (Part # 7350P-611)
Caster Kit (Part # 7350P-227)
Flow Switch Kit (Part # 7350P-741) (Two (2) are required)

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Stainless to PVC Vent Adapter (6” - Part # 7350P-275, 8” Part # 7350P-375)
Intake / Exhaust Screen (6” – Part # SSV6.6, 8” – Part # SSV8.6)
NOTE: When using an optional system sensor, pipe insulation must be wrapped around it to improve temperature measurement
accuracy and increase overall system efficiency.
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.
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.

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Incorrectly-sized expansion tank
6. Clean and flush system when reinstalling a boiler.
NOTE: This boiler must be installed within the prescribed clearances. If local building codes require additional clearance, these codes
supersede HTP’s. It is recommended to make note of the boiler model and serial number before finalizing installation.
B. FLOORING
Assure that the floor and structure of the installation location are sufficient to support the full installed weight of the boiler, including
water content of the heat exchanger and related piping. Failure to ensure the floor and structure of the installation location are
structurally sound before installation of the boiler can result in structural failure, substantial property damage, severe personal injury, or
death.
This boiler is approved for installation on combustible flooring, but must never be installed on carpeting. Installing this boiler on
carpeting could result in fire, explosion, property damage, severe personal injury, or death.
C. LEVELING AND DIMENSIONS
NOTE: It is recommended that the boiler be installed on a 4 –6” raised boiler pad, rated for the weight of the fully operational boiler and
related piping. If flooding is a concern, it is recommended to further elevate the boiler pad to prevent water from reaching the boiler.
Figure 1 - Leveling
In order for the condensate to properly flow out of the collection system, the area where you locate the boiler must be level. The boiler
comes equipped with leveling feet. Should you find the floor beneath the boiler is uneven, adjust the leveling feet with a wrench.

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Figure 2 –Specifications and Dimensions
D. CLEARANCES FOR SERVICE ACCESS
See Figure 3 for recommended service clearances. If you do not provide the minimum clearances shown, it might not be possible to
service the boiler without removing it from the space.
Space must be provided with combustion / ventilation air openings correctly sized for all appliances located in the same space as the
boiler. The boiler venting cover must be securely fastened to prevent it from drawing air from 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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Check with your local Authority Having Jurisdiction for requirements when installing boiler. 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.
E. EXHAUST VENT AND INTAKE PIPE
The appliance 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.
NOTE: The venting options described here (and further detailed in the Venting section of this manual) are the lone venting
options approved for this appliance. Failure to vent the appliance in accordance with the provided venting instructions will
void the warranty.
Failure to vent the appliance properly will result in serious personal injury or death.
Vents must be properly supported. Appliance exhaust and intake connections are not designed to carry heavy weight. Vent support
brackets must be within 1’ of the appliance and the balance at 4’ intervals. Appliance must be readily accessible for visual inspection for
the first 3’ from the appliance.
1. DIRECT VENT INSTALLATION OF EXHAUST VENT AND INTAKE PIPE
If installing a direct vent option, combustion air must be drawn from the outdoors directly into the appliance intake, and exhaust must
terminate outside. There are three basic direct vent options detailed in this manual: 1. Side Wall Venting, 2. Roof Venting, and 3.
Unbalanced Venting.
Be sure to locate the appliance such that the exhaust vent and intake piping can be routed through the building and properly
terminated. Different vent terminals can be used to simplify and eliminate multiple penetrations in the building structure (see Optional
Equipment in Venting Section). The exhaust vent and intake piping lengths, routing and termination methods must all comply with the
methods and limits given in the Venting section of this manual.
When installing a combustion air intake from outdoors, care must be taken to utilize uncontaminated combustion air. NOTE: To
prevent combustion air contamination, see Table 1.
Figure 3 –Service Clearances

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LP- 428 REV. 9.2.14
2. INDOOR COMBUSTION AIR INSTALLATION IN CONFINED OR UNCONFINED SPACE
This appliance requires fresh, uncontaminated air for safe operation and must be installed in a mechanical room where there is
adequate combustion and ventilating air. NOTE: To prevent combustion air contamination, see Table 1.
Combustion air from the indoor space can be used if the space has adequate area or when air is provided through a duct or louver to
supply sufficient combustion air based on the appliance input. Never obstruct the supply of combustion air to the appliance. If the
appliance is installed in areas where indoor air is contaminated (see Table 1) it is imperative that the appliance be installed as direct
vent so that all combustion air is taken directly from the outdoors into the appliance intake connection.
Unconfined space is space with volume greater than 50 cubic feet per 1,000 Btu/hour (4.8 cubic meters per kW) of the total input
rating of all fuel-burning appliances installed in that space. Rooms connected directly to this space, through openings not furnished with
doors, are considered part of the space.
Confined space is space with volume less than 50 cubic feet per 1,000 Btu/hour (4.8 cubic meters per kW) of the total input rating of
all fuel-burning appliances installed in that space. Rooms connected directly to this space, through openings not furnished with doors,
are considered part of the space.
When drawing combustion air from inside a conventionally constructed building to a confined space, such space should be provided
with two permanent openings: one located 6” (15 cm) below the space ceiling, the other 6” (15cm) above the space floor. Each opening
should have a free area of one square inch per 1,000 Btu/hr (22cm2/kW) of the total input of all appliances in the space, but not less
than 100 square inches (645cm2).
If the confined space is within a building of tight construction, air for combustion must be obtained from the outdoors as outlined in the
Venting Section of this manual.
When drawing combustion air from the outside into the mechanical room, care must be taken to provide adequate freeze protection.
Do not attempt to vent this appliance by any means other than those described in this manual. Doing so will void the warranty, and may
result in severe personal injury or death.
Failure to provide an adequate fresh combustion air can cause poisonous flue gases to enter living space, which could result in severe
personal injury or death. To prevent combustion air contamination, see Table 1.
F. PREVENT COMBUSTION AIR CONTAMINATION
Install intake piping for the boiler as described in the Venting section. Do not terminate exhaust in locations that can allow
contamination of intake air.
You must pipe outside air to the boiler intake. Ensure that the intake air will not contain any of the contaminants below. For example, do
not pipe intake near a swimming pool. 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.
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 1 –Contaminants

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LP- 428 REV. 9.2.14
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).
G. REMOVING A BOILER FROM A COMMON VENT SYSTEM
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, the following steps must be followed.
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 could
cause an unsafe condition.
3. If practical, close all building doors, windows and all doors between the
common venting system 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 so the installation conforms to the National Fuel Gas
Code, ANSI Z223.1. When resizing any portion of the common venting system, the common venting system should be resized to
approach the minimum size as determined using the appropriate tables in Appendix G in the National Fuel Gas Code, ANSI Z 223.1.
H. UNCRATING AND MOVING BOILER
Uncrating Boiler –Any claims for damage in shipment must be filed immediately against the transportation company by the consignee.
Cold Weather Handling –If boiler has been stored in a very cold location (below 0oF) before installation, handle with care until the
plastic components come to room temperature.
The boiler is very heavy. If the location is not level, adjust the boiler’s leveling feet to ensure a level boiler and proper flow of
condensate. If surface flooring is rough, care should be taken not to catch the leveling feet and damage the boiler when moving it into
position.
PART 4 –BOILER PIPING
Failure to follow the instructions in this section WILL VOID the warranty and may result in property damage, serious injury, or death.
Do not install the boiler into a common vent with any other boiler. This will cause flue gas spillage or boiler malfunction, resulting in
possible substantial property damage, severe personal injury, or death.
Figure 4 –CO Warning Label

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LP- 428 REV. 9.2.14
Never use dielectric unions or galvanized steel fittings when connecting to a stainless steel storage tank or boiler. Failure to follow this
instruction can lead to premature failure of the boiler system. Such failures ARE NOT covered by warranty.
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 an indirect water heater to supply domestic hot water. HTP offers 119 and 175 gallon size indirect water heaters
in 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 the appliance. Use one wrench to prevent the appliance return or supply line from
turning. Failure to prevent piping connections from turning could cause damage to appliance components.
The 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 level in the heat exchanger. Some codes/jurisdictions may require
additional external controls.
B. RELIEF VALVE
Connect discharge piping to a safe disposal location following the guidelines on the following page.
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.
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, replace it with a new 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.
C. 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 Boiler Piping Details).

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LP- 428 REV. 9.2.14
All piping methods shown in this manual use primary/secondary connection to the boiler loop. This is to avoid the possibility of
inadequate flow through the boiler. For other piping methods, consult your local HTP representative, or refer to Boiler Piping Details in
this manual.
D. SYSTEM WATER PIPING METHODS
EXPANSION TANK AND MAKE-UP WATER
1. Ensure that the expansion tank is sized to correctly handle boiler and system water volume and temperature.
BOILER WATER VOLUME
MODEL
GALLONS
1000
8.4
1700
11.6
Table 2
Undersized expansion tanks cause system water to be lost from the relief valve, causing make-up water to be added. Eventual boiler
failure can result due to excessive make-up water addition. SUCH FAILURE IS NOT COVERED BY WARRANTY.
2. The expansion tank must be located as shown in Boiler Piping Details, or following recognized design methods. See expansion 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.
DIAPHRAGM (OR BLADDER) EXPANSION TANK
Always install an automatic air vent on top of the air separator to remove residual air from the system.
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 an air cushion. An automatic air vent would cause air to leave the system, resulting in improper operation of the expansion tank.
E. CIRCULATORS
DO NOT use the boiler circulator in any location other than the ones shown in this manual. The boiler circulator location is selected to
ensure adequate flow through the boiler. Failure to comply with this caution could result in unreliable performance and nuisance
shutdowns from insufficient flow.
SIZING SPACE HEAT SYSTEM PIPING
1. In all diagrams, the space heating system is isolated from the boiler loop by the primary/secondary connection.
2. Size the piping and components in the space heating system using recognized design methods.
F. HYDRONIC PIPING WITH CIRCULATORS, ZONE VALVES, AND MULTIPLE BOILERS
The boiler is designed to function in a closed loop hydronic system. The included temperature and pressure gauge allows the user to
monitor 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 boiler installation must have an air elimination device that will remove air
from the system.
Install the boiler so the gas ignition system components are protected from water (dripping, spraying, etc.). Allow clearance for basic
service of the boiler circulator, valves, and other components. Observe minimum 1” clearance around all uninsulated hot water pipes
when openings around pipes are not protected by non-combustible materials.
On a boiler installed above radiation level, some states and local codes require a low water cut off device. This is provided standard on
the Mod Con boiler. Check with local codes for additional requirements. If the boiler supplies hot water to heating coils in air handler
units, flow control valves or other devices must be installed to prevent gravity circulation of boiler water in the coils during the cooling
cycle. Chilled water medium must be piped in parallel with the boiler.

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LP- 428 REV. 9.2.14
Freeze protection for new or existing systems must use glycol specifically formulated for this purpose. This glycol must include
inhibitors that will prevent it from attacking metallic system components. Make certain that the system fluid is checked for the correct
glycol concentration and inhibitor level. The system should be tested at least once a year and as recommended by the producer of the
glycol solution. Allowance should be made for the expansion of the glycol solution in the system piping. Example: 50% by volume glycol
solution expands 4.8% in volume for the temperature increase from 32oF to 180oF, while water expands 3% over the same temperature
rise.
Never use dielectric unions or galvanized steel fittings when connecting to a stainless steel storage tank or boiler. Failure to follow this
instruction can lead to premature failure of the boiler system. Such failures ARE NOT covered by warranty.
The boiler should not be operated as a potable hot water heater. The boiler should not be used as a direct hot water heating device.
Basic steps are listed below that will guide the installation of the boiler.
1. Connect the system return marked “Boiler Return”.
2. Connect the system supply marked “Boiler Supply”.
3. Install purge and balance valve or shut off valve and drain on system return to purge air out of each zone.
4. Install a back flow preventer on the cold feed make-up water line.
5. Install a pressure reducing valve on the cold feed make-up water line (15 PSI nominal on the system return). Check temperature and
pressure gauge when operating. It should read a minimum pressure of 12 PSI.
6. Install a circulator as shown in piping details (this section). Make sure the circulator is properly sized for the system and friction loss.
7. Install an expansion tank on the system supply. Consult the tank manufacturer’s instructions for specific information relating to
expansion tank installation. Size the expansion tank for the required system volume and capacity.
8. Install an air elimination device on the system supply.
9. Install a drain valve at the lowest point of the system. NOTE: The boiler cannot be drained completely of water without purging the
unit with an air pressure of 15 PSI.
10. The relief valve is installed at the factory. A pipe discharge line should be installed to discharge 6” above the drain in the event of
pressure relief. The pipe size must be the same size as the relief valve outlet. NEVER BLOCK THE OUTLET OF THE SAFETY
RELIEF VALVE.
G. CIRCULATOR SIZING
In addition, the boiler heat exchanger has a minimum total water volume that must be taken into account when sizing the circulator.
Minimum boiler flow rates are listed in the table below.
MODEL
MINIMUM BOILER FLOW RATE (GPM)
MODCON1000
66
MODCON1700
109
Table 3 –Minimum Boiler Flow Rates
The boiler heat exchanger does have a pressure drop which must be considered in system design. Refer to the graph in Figure 5 for
pressure drop through the boiler heat exchanger.

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LP- 428 REV. 9.2.14
Figure 5 –Heat Exchanger Pressure Drop Chart
Table 4 represents the various system design temperature rise through the boiler, along with respective flows and friction loss which will
aid in circulator selection.
SYSTEM TEMPERATURE RISE CHART
20o∆t
25o∆t
30o∆t
MODEL
Friction Feet
Flow GPM
Friction Feet
Flow GPM
Friction Feet
Flow GPM
MODCON1000
19
100
11
80
8
66
MODCON1700
35
170
26
130
18
109
Table 4 –Temperature Rise Chart
Figure 6 represents the combined flow rates and pipe sizes when using multiple boilers to design the manifold system for the primary
circuit. To size, simply add up the number of boilers and the required flow rates for the system design temperature.

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LP- 428 REV. 9.2.14
Figure 6 –Multiple Boiler Manifold Piping
H. FILL AND PURGE HEATING SYSTEM
Attach the hose to balance and purge hose connector or drain valve and run hose to nearest drain.
Close the other side of the balance and purge valve or the shut off valve after the drain.
Open first zone balance and purge or drain valve to let water flow out the hose. If zone valves are used, open the valves one
at a time manually. (NOTE: You should check the valve manufacturer’s instructions prior to opening valves manually, so as
not to damage the valves.)
Manually operate fill valve regulator. When water runs out of the hose, you will see a steady stream of water (without bubbles).
Close balance and purge valve or drain to stop the water from flowing. Disconnect the hose and connect it to next zone to be
purged.
Repeat this procedure for additional zones (one at a time).
For installation that incorporates standing iron radiation and systems with manual vents at the high points, follow previous section and,
starting with the nearest manual air vent, open until water flows out. Then close vent. Repeat procedure, working your way toward the
furthest air vent. It may be necessary to install a basket strainer in an older system where larger amounts of sediment may be present.
Annual cleaning of the strainer may be necessary.
Upon completion, make sure that the fill valve is in the automatic position and each zone balance and purge or shut off is in an open
position and zone valves are positioned for automatic operation.
I. FREEZE PROTECTION FLUIDS
Use only inhibited glycol solutions which are specially formulated for hydronic systems. Ethylene glycol is toxic and can attack gaskets
and seals used in hydronic systems. Glycol mixtures should not exceed 50%.
1. Glycol in hydronic applications is specially formulated for this purpose, and includes inhibitors that prevent the glycol from attacking
metallic system components. Make certain that the system fluid is checked for the correct glycol concentration and inhibitor level.