HydroTherm HeatNet KN6 User manual

is manual is intended only for use by a qualied heating installer/technician. Read and follow this manual, all supplements and related
instructional information provided with the boiler. Install, start and service the boiler only in the sequence and methods given in these
instructions. Failure to do so can result in severe personal injury, death or substantial property damage.
Do not use the boiler during construction. Construction dust and particulate, particularly drywall dust, will cause contamination of
the burner, resulting in possible severe personal injury, death or substantial property damage. e boiler can only be operated with a dust-
free air supply. Follow the instruction manual procedures to duct air to the boiler air intake. If the boiler has been contaminated by operation
with contaminated air, follow the instruction manual guidelines to clean, repair or replace the boiler if necessary.
Ax these instructions near to the boiler/water heater. Instruct the building owner to retain the instructions for future use by a qualied
service technician, and to follow all guidelines in the User’s Information Manual.
10/12 Copyright 2010 Hydrotherm
Cast Iron Condensing Boilers
Models KN
- 6, KN-10, KN-16,
KN-20, KN-26 and KN-30
Boiler Manual
Installation and Operation
Instructions
MEA #444-05-E
MASS Plumbers
#G1-06-04-28
IOMKN-2-0213
42-9533
Also read and follow:
KN Control Manual

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Cast Iron Condensing Boilers – Installation Manual
If the information in this manual is not followed
exactly, a fire or explosion may result causing
property, personal injury or loss of life.
Do not store or use gasoline or other flammable vapors
and liquids in the vicinity of this or any other appliance.
WHATTO 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 phone
outside of the building. Follow the gas supplier’s
instructions.
• If you cannot reach your gas supplier, call the fire
department.
Installation and service must be performed by a qualified
installer, service agency or the gas supplier.
Assurez-vous de bien suivre les instructions
données dans cette notice pour réduire au
minimum le risque d’incendie ou d’explosion ou
pour éviter tout dommoge matériel, toute
blessure ou la mort
Ne pas entreposer ni utiliser d’essence ou ni d’autres
vapeurs ou liquides inflammables à proximité de cet
appareil ou de tout autre appareil.
QUE FAIRE SIVOUS SENTEZ UNE ODEUR DE GAZ:
• Ne pas tenter d’allumer d’appareil.
• Ne touchez à aucun interrupteur; ne pas vous servir
des téléphones se trouvant dans le bâtiment.
• Appelez immédiatement votre fournisseur de gas
depuisunvoisin.Suivezlesintructionsdu fournisseur.
• Si vous ne purvez rejoindre le fournisseur, appelez le
service des incendies.
L’installation et l’entretien doivent être assurés par un
installateur ou un service d’entretien qualifié ou par le
fournisseur de gaz.
Failure to properly vent this unit can cause
excessive amounts of carbon monoxide resulting
in severe personal injury or death!
Do not use automotive anti-freeze in the boiler
waterways. If the use of anti-freeze is necessary
an anti-freeze specifically formulated for hydronic
heating systems must be used or damage to the
boiler may occur voiding the warranty!
DESIGNED AND TESTED ACCORDING TO A.S.M.E.
BOILER AND PRESSURE VESSEL CODE, SECTION IV
FOR A MAXIMUM ALLOWABLE WORKING PRESSURE
OF 100 PSI, 700 kPa WATER.
INSTALLER, THESE INSTRUCTIONS TO BE AFFIXED
ADJACENTTO THE BOILER / WATER HEATER.
CONSUMER, RETAIN THESE INSTRUCTIONS FOR
FUTURE REFERENCE PURPOSES.
CONTENTS
BeforeYour Start.................................................page 2
Ratings & Capacities..........................................page 3
Location..............................................................page 3
Combustion Air &Ventilation..............................page 3
Venting Guidelines..............................................page 5
Common Vent Systems ...................................page 12
General Piping Requirements ..........................page 13
Heating System Piping.....................................page 14
Domestic Water Supply Piping.........................page 17
Condensate Piping...........................................page 19
Gas Supply Piping............................................page 19
Electrical Wiring................................................page 20
Boiler Operation................................................page 21
Operating Instructions ......................................page 21
Sequence of Operation.....................................page 24
Ignition Troubleshooting....................................page 26
Checking & Adjustment....................................page 27
Diagnostics.......................................................page 28
Maintenance.....................................................page 29
Pressure Switches............................................page 30
Wiring ...............................................................page 32
Start-Up............................................................page 35
Repair Parts......................................................page 37
Warranty...........................................................page 48
BEFOREYOU START
This manual covers the application, installation,
operation and maintenance of a KN series boiler.
To obtain the safe, dependable, efficient operation and
long life for which this boiler was designed, these
instructions must be read, understood and followed.
The KN boiler series has been design certified by CSA
for use with natural gas under the latest revision of
ANSI-Z21.13/CSA 4.9, Gas-Fired Hot Water Boilers and
CAN1-3.1, Industrial and Commercial Gas Fired
Packaged Boilers. Each unit has been constructed and
hydrostatically tested for a maximum working pressure
of 100 psi, 700 kPa, in accordance with Section IV of the
A.S.M.E.Boiler and Pressure Vessel Code.
All aspects of the boiler installation must conform to the
requirements of the authority having jurisdiction, or, in
the absence of such requirements, to the National Fuel
Gas Code, ANSI Z223.1/NFPA 54-latest revision.Where
required by the authority having jurisdiction, the
installation must conform to the Standard for Controls
and Safety Devices for Automatically Fired Boilers,
ANSI/ASME CSD-1.
Ifinstalledinthe Commonwealth of Massachusetts,you
MUSTFOLLOWtheadditional instructions contained in
HydroTherm’s instruction sheet MACODE-3.Please
refer to the back of this manual for required regulations.
In Canada, the installation must be in accordance with
the requirements of CSA B149.1 or .2, Installation Code
for Gas Burning Appliances and Equipment.

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Cast Iron Condensing Boilers – Installation Manual
The owner should maintain a record of all service work
performed with the date and a description of the work
done. Include the name of the service organization for
future reference.
Direct all questions to your HydroTherm distributor or
contact the HydroTherm Customer Service Department
at: 260 North Elm Street, Westfield, MA 01085. Always
include the model and serial numbers from the rating
plate of the boiler in question.
RATINGS & CAPACITIES
Before installing the KN boiler check the rating plate to
ensure that the unit has been sized properly for the job.
Also ensure that the unit has been set up for the type
of gas available at the installation site. Other important
considerations are the availability of an adequate
electrical supply, fresh air for combustion and a suitable
vent system.
BOILER LOCATION
1. This boiler is suitable for indoor installations only.
Locate the boiler in an area that provides good
access to the unit. Servicing may require the
removal of jacket panels. Allow the minimum
clearances between adjacent construction and the
boiler as listed in Table 1.
Service clearances are not mandatory, but
are recommended to ensure ease of service
should it be required.
Table 1 - Clearances
2. An optimum site will be level, central to the piping
system, close to a chimney or outside wall and have
adequate fresh air for combustion.Ensure that the
unit is level from front to back and from side to side.
Usemetal shims iflevelingis required.Electrical and
electronic components must be protected from
exposuretowaterduringoperationand maintenance.
DO NOT install this boiler in a location that would
subject any of the gas ignition and other electronic
componentsto directcontactwith waterorexcessive
moisture during operation or servicing.
3. Ensure that the floor is structurally sound and will
support the weight of the boiler.
The KN may be installed directly on
combustible flooring, but never on carpeting.
4. Locate the boiler in an area that will prevent water
damage to adjacent construction should a leak
occur or during routine maintenance.
5. DO NOT place this boiler in a location that would
restrict the introduction of combustion air into the
unit or subject it to a negative pressure unless the
combustion air is piped from the outside, see the
COMBUSTION AIR & VENTILATION section.
6. NEVER place this boiler in a location that would
subject it to temperatures at or near freezing.
Never store combustible materials, gasoline
or any product containing flammable vapors
orliquids inthevicinity ofthe boiler. Failureto
comply with this warning can result in an
explosion or fire causing extensive property
damage,severepersonal injury ordeath!
COMBUSTION AIR &VENTILATION
Thisboiler mustbesupplied withcombustion
air in accordance with Section 5.3, Air for
Combustion & Ventilation, of the latest
revisionof theNationalFuel GasCode,ANSI
Z223.1/NFPA 54 and all applicable local
building codes. Canadian installations must
comply with CSA B149.1 or .2 Installation
Code for Gas Burning Appliances and
Equipment, or applicable provisions of the
local building codes. Failure to provide
adequatecombustionairforthis boiler/water
heatercanresultinexcessivelevelsofcarbon
monoxidewhichcanresultinseverepersonal
injury or death!
To operate properly and safely this boiler requires a
continuous supply of air for combustion. NEVER store
objects on or around the boiler!
Combustion air contaminated with fluoro-
carbons or other halogenated compounds
such as cleaning solvents and refrigerants
will result in the formation of acids in the
combustion chamber.These acids will cause
premature failure of the boiler voiding the
warranty!
If the boiler is operated while the building is
under construction it must be protected from
wood, concrete, sheet rock and other types
of dust. Failure to properly protect the unit
from construction dust will damage the unit
voiding the warranty!
Clearance to Combustibles Service Clearance
in mm in mm
Top 6 153 24 610
Back 6153 24 610
Left Side 6 153 6152
Right Side 6 153 6152
Front 6 153 36 914
Flue 6 153

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Cast Iron Condensing Boilers – Installation Manual
Buildings will require the installation of a fresh air duct
or other means of providing make-up air if the intake
air option isn't used. Any building utilizing other gas
burning appliances, a fireplace, wood stove or any type
of exhaust fan must be checked for adequate
combustion air when all of these devices are in
operation at one time.Sizing of an outside air duct must
be done to meet the requirements of all such devices.
Never operate the KN in an environment
subjected to a negative pressure unless it is
Direct Vented. Failure to comply with this
warning can result in excessive levels of
carbon monoxide causing severe personal
injury or death!
All Air From InsideThe Building
If the boiler is to be located in a confined space the
minimum clearances listed in Table 1 must be
maintained between it and any combustible construction.
When installed in a confined space without the intake
air option two permanent openings communicating with
an additional room(s) are required. The combined
volume of these spaces must have sufficient volume to
meet the criteria for an unconfined space.The total air
requirements of all gas utilization equipment, fireplaces,
wood stoves or any type of exhaust fan must be
considered when making this determination. Each
opening must have a minimum free area of 1 in2/1000
Btu/hr, 2200 mm2/kW based on the total input rating of
ALL gas utilization equipment in the confined area.Each
opening must be no less than 100 in2, 64,516 mm2in
size.The upper opening must be within 12 in, 300 mm
of, but not less than 3 in, 80 mm from, the top of the
enclosure. The bottom opening must be within 12 in,
300 mm of, but not less than 3 in, 80 mm from, the
bottom of the enclosure.
All Air From OutsideThe Building
When installed in a confined space without the intake
air option two permanent openings communicating
directly with, or by ducts to, the outdoors or spaces that
freely communicate with the outdoors must be present.
The upper opening must be within 12 in, 300 mm of,
but not less than 3 in, 80 mm from, the top of the
enclosure. The bottom opening must be within 12 in,
300 mm of, but not less than 3 in, 80 mm from, the
bottom of the enclosure.
Where directly communicating with the outdoors or
communicatingwith the outdoors through vertical ducts,
each opening shall have a minimum free area of 1in2/
4000 Btu/hr, 550 mm2/kW of the total input rating of all
oftheequipment in the enclosure.
Where communicating with the outdoors through hori-
zontal ducts, each opening shall have a minimum free
area of 1 in2/2000 Btu/hr, 1100 mm2/kW of the total
input rating of all of the equipment in the enclosure.
When ducts are used, they must have the same cross-
sectional area as the free area of the opening to which
they connect.
Table 2 - Make-up Air Duct Sizing
When calculating the free area necessary to meet the
make-up air requirements of the enclosure,
consideration must be given to the blockage effects of
louvers, grills and screens.
Screens must have a minimum mesh size of 1/4 in,
6.4 mm. If the free area through a louver or grill is not
known ducts should be sized per Table 2.
Direct Intake Air Option - General
This configuration provides combustion air directly to the
boiler’s air intake using a dedicated pipe when using the
direct vent option. Combustion air can be drawn in
horizontally through an outside wall or vertically through
the roof, see Figures 2, 3, 4 & 5. It must be sized per
Table 3.
Single wall galvanized smoke pipe, single wall aluminum
pipe, flexible aluminum pipe, PVC or CPVC pipe can be
used for the intake air pipe.
Table 3 - Intake Air Pipe Sizing
Required Cross Sectional Duct Area
Input
(MBH)
1/4 in, 6.4 mm
Wire Screen
Metal
Louvers
Wooden
Louvers
in2cm2in2cm2in2cm2
600 150 967 200 1292 600 3869
1000 250 1612 334 2154 1000 6448
1600 400 2580 533 3439 1600 10,322
2000 500 3224 668 4308 2000 12,896
2600 650 4194 894 5595 2600 16,772
3000 750 4836 1002 6462 3000 19,344
Model
Size
Pipe Diameter
in2mm2
600 5 127
1000 6152
1600 6152
2000 9229
2600 8203
3000 8203

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Cast Iron Condensing Boilers – Installation Manual
All joints in metal intake air systems must be
secured using corrosion resistant fasteners
and sealed using a suitable Silicone caulk.If
PVC or CPVC is used, the joints must be
cleanedwithasuitablesolventand connected
using a solvent based PVC cement. The
intakeair system MUST besupported bythe
building structure not the boiler.
Direct Intake Air Option - Vertical
The maximum equivalent length for the vertical intake air
pipe is 80 ft, 19.7 m for KN-6, 10, 20, 120 ft, 36.6 m for
KN-16, 26, 30. Each 90° mitered elbow and the intake
air cap are equal to 10 ft, 3.3 m of straight pipe. If 90°
long sweep elbows are installed use the manufacturers
recommended equivalent length.
A listed, nonrestrictive intake air cap must be used.The
intake air cap must terminate as shown in Figure 4.The
penetration point in the roof must be properly flashed
and sealed.
Direct Intake Air Option - Horizontal
The maximum equivalent length for the horizontal
intake air pipe is 80 ft, 19.7 m for KN-6, 10, 20, 120 ft,
36.6 m for KN-16, 26, 30.Each 90° mitered elbow and
theintakeairterminal are equalto10 ft,3.3 m of straight
pipe. If 90° long sweep elbows are installed use the
manufacturers recommended equivalent length.
Horizontal runs that exceed 5 ft, 1.5 m must be
supported at 3 ft, 0.98 m intervals with overhead
hangers. The intake air terminal must terminate as
shown in Figures 2, 3 or 5.
GENERALVENTING GUIDELINES
The vent installation must be in accordance
with Part 7, Venting of Equipment, of the
NationalFuel Gas Code,ANSI Z223.1/NFPA
54-latest revision or applicable provisions of
thelocalbuildingcodes.Canadianinstallations
mustcomplywithCSAB149.1or.2Installation
Code. Improper venting can result in
excessive levels of carbon monoxide which
can result in severe personal injury or death!
All vent systems must be fully supported by the building
structure and not by the boiler. Appropriate thimbles and
fire-stops must be used where required.
Improper installation of common positive
pressureventsystemscan resultinexcessive
levels of carbon monoxide which can cause
severe personal injury or death!
A barometric damper or blast gate as
required, must be installed if a Category II
vertical vent system produces a negative
draft in excess of 0.15 in, 3.8 mm WC at the
flue outlet. Size the vent system per local
codes and the vent pipe manufactuers
requirements, using generally accepted
engineering practices).
VENT SYSTEM OPTIONS
The KN may be vented the following ways:
1) Direct Vent (individual venting only) (page
8 & 9) - Positive Pressure, Category IV uses a
stainless steel vent system certified to UL 1738 for
installations in the United States, and a stainless
steel vent system certified to ULC S636 for
installations in Canada. Combustion air is piped
from the outdoors to the blower inlet.
2) SideWallVent (individual venting only) (page 10)
- Positive Pressure, Category IV uses a stainless
steel vent system certified to UL 1738 for
installations in the United States, and a stainless
steel vent system certified to ULC S636 for
installations in Canada. Combustion air is obtained
from the space in which the unit is installed.
To ensure proper operation, boilers that are
sidewall vented and use room air must not
be fired less than 25% input.
3) Vertical Vent (individual venting only) (page
10) - Positive Pressure, Category IV uses a
stainless steel vent system certified to UL 1738 for
installations in the United States, and a stainless
steel vent system certified to ULC S636 for
installations in Canada. Combustion air is obtained
from the space in which the unit is installed.
4) Vertical Vent (individual venting only) (page 11)
- Negative Pressure, Category II uses stainless
steel vent system certified to UL 1738 for
installations in the United States, and a stainless
steel vent system certified to ULC S636 for
installation in Canada. Combustion air is obtained
from the space in which the unit is installed.
5) Common Vent (page 7) - Negative Pressure,
Category II (Positive Pressure, Category IV - KN-16,
26, 30 only) uses a stainless steel vent system
certified to UL 1738 for installations in the United
States, and a stainless steel vent system certified to
ULC S636 for installations in Canada.

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Cast Iron Condensing Boilers – Installation Manual
When horizontal vent runs exceed 5 ft, 1.5m they must
be supported at 3 ft, 0.98 m intervals with overhead
hangers. If any part of a single wall metal vent system
passes through an unheated space it must be insulated
with insulation rated for 400°F, 212°C.
Horizontal vent systems shall terminate at least 4 ft,
1.3 m below, 4 ft, 1.3 m horizontally from or 1 ft,
0.23 m above any door, window or gravity air inlet into
any building. It must not terminate less than 4 ft, 1.3 m
horizontally from, and in no case above or below, unless
a 4 ft, 1.3 m horizontal distance is maintained, from
electric meters, gas meters, regulators and relief
equipment and not less than 7 ft, 2.3 m above adjacent
public walkway.The bottom of the vent terminal(s) shall
be located at least 5 ft, 1.5 m above the air intake
terminal(s) unless thereisa 5 ft, 1.5mdistance between
them.
Avoid terminal locations likely to be affected by winds,
snowdrifts, people and pets. Protect building materials
and vegetation from degradation caused by the flue
gases.
When running horizontal combustion air and venting for
single or multiple units, exhaust and combustion air
terminals must be installed on the same plane (outside
wall) in order to prevent pressure differences due to
prevailingwinds.Incoldclimates,double-wallorinsulated
inlet pipe recommended to prevent condensation.
Vertical Direct Vent Systems - see Figure 4
The vent materials used in positive pressure vent
systems must be certified to UL 1738 for installations in
theUnitedStates, ULCS636forinstallations in Canada.
If any part of a single wall metal vent system passes
through an unheated space it must be insulated with
insulationrated for400°F, 204°C.Structuralpenetrations
must be made using approved fire-stops.
The top of a vertical vent system must extend at least
51/2ft, 1.8 m above the roof surface that it passes
through, 4 ft, 1.3 m above the intake air cap, see Figure
4. In addition the vent system must conform to the
dimensions shown in Figure 4.The penetration point in
the roof must be properly flashed and sealed.
The vent system must be gas tight.All seams and joints
in metal pipes must be joined and sealed in accordance
with the vent system manufacturer's instructions.
Combination Direct Vent Systems - see Figure 5
The boiler can be vented vertically with the intake air
piped horizontally through an outside wall. Follow the
instructions in theINTAKEAIROPTION - HORIZONTAL
GUIDELINES on page 5. Also follow the general
instructions in the COMBUSTION AIR & VENTILATION
andGENERALVENTINGGUIDELINESsections.
The maximum equivalent length for the total
flue outlet vent system for Category IV
conditions is 80 ft, 19.7 m for KN-6, 10, 20;
120 ft, 36.6 m for KN-16, 26, 30. Use Table
4 for equivalent lengths per fitting.Table 4 -
“Category IV Equivalent Length per Fitting”
chart is meant as a guideline for preliminary
sizing. If vent length approaches 75% of
maximum length listed, an engineered vent
system calculation must be performed.
Consult factory.
Table 4 - Category IV Equivalent Length per Fitting
DIRECTVENT
POSITIVE PRESSURE,CATEGORY IV
In this configuration the boiler blower is used to push
the flue products to the outdoors while drawing
combustion air from the outdoors. The INTAKE AIR
OPTION instructions under the COMBUSTION AIR &
VENTILATION SECTION must be followed!
Horizontal Direct Vent Systems - Figures 2 & 3
The vent materials used in positive pressure vent
systems must be certified to UL 1738 for installations in
the United States, ULC S636 for installations in Canada.
To maximize the performance of single wall sheet metal
vent systems locate 90° elbows as far from the boiler as
possible and from one another. For best results,
horizontal vent systems should be as short and straight
as possible.
The vent system must be both gas and water tight.
All seams and joints in metal pipes must be joined and
sealedinaccordancewiththeventsystemmanufacturer’s
instructions.
Model/Outlet Diameter K* KN6 KN10 KN16
5 " 6 " 6 "
Standard Tee 1.25 20 ft 25 ft 25 ft
Boot Tee 0.65 10 ft 15 ft 15 ft
Cap - Low Res (UL) 0.50 10 ft 10 ft 10 ft
45° w/Bird Screen 0.40 10 ft 10 ft 10 ft
Elbow - 90° 0.38 10 ft 10 ft 10 ft
Elbow - 45° 0.15 5 ft 5 ft 5 ft
Model/Outlet Diameter K* KN20 KN26 KN30
8 " 8 " 8 "
Standard Tee 1.25 30 ft 35 ft 35 ft
Boot Tee 0.65 15 ft 15 ft 15 ft
Cap - Low Res (UL) 0.50 15 ft 15 ft 15 ft
45° w/Bird Screen 0.40 10 ft 10 ft 10 ft
Elbow - 90° 0.38 10 ft 10 ft 10 ft
Elbow - 45° 0.15 5 ft 5 ft 5 ft
*Equivalent lengths based on K factors and (5X)
pipe diameters straight length between ttings.

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Cast Iron Condensing Boilers – Installation Manual
Figure 1 - KN Series Multiple Boiler Common Venting
VERTICAL CHIMNEY VENTING -
Vertical venting - multiple boiler
installations:
DO NOT common vent
more than the following
numbers of KN boilers:
KN - 6/10/16 (5) boilers
maximum
KN - 20/26/30 (4) boilers
maximum
Consult factory for
applications requiring
more boilers and/or use
an engineered venting
system solution.
It is required that the boiler nearest
the vertical chimney be fired first
when the horizontal distance exceeds
50% of the vertical distance. Refer to
the HeatNet manual on how to select
the lead boiler.
Whensizedfora(CATII)configuration,
a negative pressure of 0.02 to 0.15 in
WC is required in each boiler’s riser
when all boilers are operating at full
input. A barometer damper must be
installed as illustrated. [Exception: if
the vent system is designed using
accepted engineering practices, and
the design calculations prove there is
no need for barometric dampers, the
barometric dampers maybe omitted.]
When required by applicable codes,
install a thermal spill switch on each
barometric damper.
When engineered for a CAT IV
configuration (KN-16, 26, 30 only) do
notexceeda positivepressure of 0.50
inches WC in each boiler riser when
all boilers are operating at high fire.
1. Connect each boiler riser to the
common vent with aY or boot T.
2. Install an approved vent cap at
each vent termination.
3. Dimensions:
B = breeching length
C = chimney height
D = breeching diameter
F = riser diameter
(No smaller than the
dimension given inTable 4,
page 6.)
4. Size the chimney and breeching
per local codes and vent pipe
manufacturer’s requirements,using
generally accepted engineering
practices. (Consult factory for
vertical heights beyond100 ft.)

8
Cast Iron Condensing Boilers – Installation Manual
Figure 2 - Horizontal Air Intake and Venting for a Single DirectVent System
Figure 3 - Horizontal Air Intake and Venting for Multiple DirectVent Systems

9
Cast Iron Condensing Boilers – Installation Manual
Figure 4 -Vertical Air Intake and Venting for Direct Vent System
Figure 5 - Combination Direct Vent Systems

10
Cast Iron Condensing Boilers – Installation Manual
SIDEWALLVENT
POSITIVE PRESSURE,CATEGORY IV
In this configuration the boiler blower is used to push the
flue products horizontally to the outdoors, see Figure 6.
To ensure proper operation, boilers that are
vented sidewall and use room air must not
fire less than 25% input.
The air for combustion is taken from the space in which
the unit is installed. The applicable instructions under
the COMBUSTION AIR & VENTILATION SECTION
must be followed! The vent guidelines under the
HORIZONTAL DIRECT VENT SYSTEMS section must
also be followed.
Figure 6 - SideWallVenting
VERTICALVENT (Recommended)
POSITIVE PRESSURE - CATEGORY IV
In this configuration the boiler blower is used to push
the flue products vertically to the outdoors, see Figure
7. The air for combustion is taken from the space in
which the unit is installed. The applicable instructions
under the COMBUSTION AIR & VENTILATION
SECTION must be followed! The vent guidelines under
the VERTICAL DIRECTVENT SYSTEMS section must
also be followed.
Figure 7 -Vertical Positive Pressure Venting

11
Cast Iron Condensing Boilers – Installation Manual
Figure 8 -VerticalVenting with a Metal Chimney System
The vent system should be sloped up toward the
chimney at a minimum rate of 1/4 in/ft, 2 cm/m.
Always provide a minimum clearance of 6 in, 152 mm
between single wall vent pipe and any combustible
materials.
Failure to maintain minimum clearances
between vent connectors and any
combustible material can result in a fire
causing extensive property damage, severe
personal injury or death!
Exit cones are favorable when used
to increase the velocity of the flue
gas exiting the stack and, may also
help, in cold climates, to reduce ice
build-up. Exit cone terminations must
be supplied by others, installed per
manufacturer’s instructions, and meet
local and federal code.
g
eneric exit cone
Note:
1) All building
structural
modifications
by others.
2) Firestopping per
local building
codes.
Model
Size
Breech & Flue Diameter
in2mm2
600 8 204
1000 12 305
1600 14 356
2000 14 356
2600 14 356
3000 14 356
VERTICALVENT (Optional)
NEGATIVE PRESSURE - CATEGORY II
The KN is listed as a Category II appliance when vented
vertically into a listed metal AL294C S.S. chimney
system, Figure 8. The chimney system must provide a
negative pressure of 0.02 to 0.15 in, 0.51 to 3.8 mmWC
at the boiler flue collar with the unit running.
When using a listed metal chimney system
the chimney system manufacturer’s
instructions must be followed.
Multiple boiler vent systems must be
designed and verified by a qualified
professional and stack manufacturer. The
vent system must prevent backflow of
exhaust gas through idle boilers.
Whenmore thanoneappliance isconnected to thesame
chimney system the system must be large enough to
safely vent the combined output of all of the appliances.
Table 5 lists the equivalent breeching and chimney
sizes required for a single boiler installation.
If an appliance using any type of a
mechanical draft system operating under
positive pressure is connected to a chimney
flue, never connect any other appliances to
this flue. Doing so can result in excessive
levels of carbon monoxide which can cause
severe personal injury or death!
Table 5 - Equivalent Breeching & Chimney Size,
Negative Pressure - Single Boiler
These sizes are based on a 20 ft, 6.1m
chimney height.
Vent Connections
Locate the boiler as close to the chimney system as
possible. Use the shortest, straightest vent connector
possible for the installation. If horizontal runs exceed
5 ft, 1.5 m they must be supported at 3 ft, 0.9 m
intervals with overhead hangers. Use the appropriate
vent connector of the same diameter as the flue collar
to connect the boiler to a listed metal chimney system.
Follow the chimney system manufacturer’s instructions
for proper assembly.

12
Cast Iron Condensing Boilers – Installation Manual
EXISTING COMMON VENT SYSTEMS
If an existing boiler is removed from a common venting
system, the common venting system may then be too
large for the proper venting of the remaining appliances
connected to it. At the time of removal of an existing
boiler, the following steps shall be followed with each
appliance remaining connected to the common venting
system placed in operation, while the other appliances
remaining connected to the common venting system are
not in operation.
Au moment du retrait d'une chaudière existante, les
mesures suivantes doivent être prises pour chaque
appareil toujours raccordé au système d'évacuation
commun et qui fonctionne alors que d'autres appareils
toujours raccordés au système d'évacuation ne fonction-
nent pas: système d'évacuation
a) Seal any unused openings in the common venting
system.
Sceller toutes les ouvertures non utilisées du sys-
tème d'évacuation.
b) Visually inspect the venting system for proper size
and horizontal pitch and determine there is no
blockageor restriction, leakage,corrosionand other
deficiencieswhichcould cause an unsafecondition.
Inspecter de façon visuelle le système d'évacu-ation
pour déterminer la grosser et l'inclinaison
horizontale qui conviennent et s'assurer que le
système est exempt d'obstruction, d'étranglement
de fruite, de corrosion et autres défaillances qui
pourraient présenter des risques.
c) Insofar as is practical, close all building doors and
windows and all doors between the space in which
the appliances remaining connected to the common
venting system are located and other spaces of the
building.Turn on clothes dryers and any appliance
not connected to the common venting system.Turn
on any exhaust fans, such as range hoods and
bathroom exhaust, so they will operate at maximum
speed. Do not operate a summer exhaust fan for a
boiler installation. Close fireplace dampers.
Dans lamesure du possible,fermertoutesles portes
et les fenêtres du bâtiment et toutes les portes entre
l'espace où les appareils toujours raccordés du
système d'évacuation sont installés et les autres
espaces du bâtiment. Mettre en marche les
sécheuses, tous les appareils non raccordés au
système d'évacuation commun et tous les
ventilateurs d'extraction comme les hottes de
cuisinère et les ventilateurs des salles de bain.
S'assurer que ces ventilateurs fonctionnent à la
vitesse maximale. Ne pas faire fonctionner les
ventilateurs d'été. Fermer les registres des
cheminées.
d) Place in operation the appliance being inspected.
Follow the lighting instructions.Adjust thermostat so
appliance will operate continuously.
Mettre l'appareil inspecté en marche. Suivre les
instructions d'allumage. Régler le thermostat de
façon que l'appareil fonctionne de façon continue.
e) After it has been determined that each appliance
remaining connected to the common venting system
properly vents when tested as outlined above, return
doors, windows, exhaust fans, fireplace dampers
and any other gas-burning appliance to their
previous condition of use.
Une fois qu'il a été d éterminé, selon la métode
indiquée ci-dessus, que chaque appareil raccordé
au système d'évacuation est mis à l'air libre de façor
adéquate. Remettre les portes et les fenêtres, les
ventilateurs, les registres de cheminées et les
appareils au gaz à leur position originale.
f) Any improper operation of the common venting
system should be corrected so the installation
conforms with the National Fuel Gas Code, ANSI
Z223.1/NFPA 54.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 F in the National Fuel Gas Code, ANSI
Z223.1/ NFPA 54 and or CSA B149 Installation
Codes.
Tout mauvais fonctionnement du systéme d'évacu-
tioncommundevraitétrécorrigédefaçorquel'instal-
lation soit conforme au National Fuel Gas Code,
ANSIZ223.1/NFPA 54et(ou)auxcodes d'installation
CSA-B149.Si la grosseur d'une section du système
d' évacuation doit étré modifiée, le système devrait
étrémodifiépourrespecterles valeursminimales des
tableauxpertinentsdel'appendice Fdu NationalFuel
Gas Code, ANSI Z223.1/NFPA 54 et (ou) des codes
d'installationCSA-B149.

13
Cast Iron Condensing Boilers – Installation Manual
Table 6
Increase flow rates approximately 30% for glycol
mixtures.
Figure 9 - Relief Valve Piping
GENERAL PIPING REQUIREMENTS
Improper piping of this boiler will void the
manufacturer’swarrantyandcancauseboiler
failure resulting in flooding and extensive
propertydamage!
Shut off valves and unions should be
installed at the inlet and outlet connections
of the boiler to provide for isolation of the
unit should servicing be necessary.
ReliefValve
Pipe the discharge of the pressure relief valve as shown
in Figure 9.Mount on rear section or vertically on supply
nipple.
Never install any type of valve between the
boiler and the relief valve or an explosion
causing extensive property damage, severe
personal injury or death may occur!
Flow Switch
The flow switch (optional on KN-6, 10, and 20;standard
on KN-16, 26 and 30) is wired to prevent the boiler from
firing unless there's adequate water flow through the
unit.
If using the optional flow switch, failure to
maintain the minimum flow rates listed in
Table 6 at the boiler outlet will prevent the
flow switch from closing. If a minimum flow
ratecannot be maintainedatthe boiler outlet
theflowswitchwill havetoberelocated inthe
system.
Water
Flow Rates
(GPM)
*ΔT Across
Heat Exchanger
Min. Max. Min. * Max.
KN-6 10 100 20°F 100°F
KN-10 15 150 20°F 100°F
KN-16 24 240 20°F 100°F
KN-20 30 300 20°F 100°F
KN-26 38 380 20°F 100°F
KN-30 45 450 20°F 100°F
*Min/Max Δt corresponds to full input, for applications
requiring operation above and/or below these parameters,
please consult manufacturer.

14
Cast Iron Condensing Boilers – Installation Manual
HEATING SYSTEM PIPING
General Piping Requirements
Allheatingsystem piping mustbe installed bya qualified
technician in accordance with the latest revision of the
ANSI/ASMEBoilerandPressureVessel Code,SectionIV.
Where required, the piping must comply with ANSI/
ASME CSD-1, Standard for Controls and Safety Devices
for Automatically Fired Boilers.
All applicable local codes and ordinances must also be
followed. A minimum clearance of 1in, 25 mm must be
maintained between heating system pipes and all
combustible construction.All heating system piping must
be supported by suitable hangers, not the boiler. The
thermal expansion of the system must be considered
when supporting the system. A minimum system
pressure of 12 psig, 84 kPa must be maintained at
boiler operating conditions. A minimum system pressure
of 25 psig, 172 kPa fill pressure is required, at boiler
operating conditions on glycol mixtures within a closed
loop.
Cleaning, Flushing System
Prior to commissioning the boiler/s, the piping/system
must be cleaned and flushed to prevent contaminants
from settling back into the boiler and fouling the heat
exchanger. Isolate the boiler from the system prior to
the cleaning process. Fill the system with water, add
the cleaning solution and circulate per the chemical
supplier’s instructions until the system TDS is within
10% of the city water TDS. Add the corrosion inhibitor
to the system and follow the chemical supplier’s
instructions.
Boiler Piping Connections
The supply and return connections should be sized to
suit the system, see Table 7.
Table 7 - Supply & Return Pipe Sizing
WaterTreatment
This boiler was designed to operate in a closed loop
heating system.Water treatment is required when fill or
make-up water contains dissolved solids greater than
200 ppm or if PH level is not within the 6.5-11 range.
For systems requiring glycol for freeze protection
use a glycol/water mix that prevents foaming. The air
entrapment within this foam significantly decreases heat
transfer and could potentially result in damage to the
sections. The formation of this foam can be controlled
rather simply by introducing an anti foaming agent to the
water/glycol mix.There are many suppliers of chemical
treatments that are acceptable; the following company
offers a mix with a heat transfer characteristics nearly
identical to water: a mixture of one gallon of anti foaming
agent per 5,000 gallons of system volume (Dow Corning
Anti foaming Agent part #1410 or equivalent).
Pump Requirements
This boiler requires a continuous minimum water flow
for proper operation. The system pump must be sized
to overcome the head loss of the boiler and the heating
system in order to achieve the required temperature rise.
If the system contains hydronic antifreeze this must be
considered when sizing the pump.The temperature rise
across the boiler must never exceed 100°F, 55.6°C.
LowWater Cutoff
Each KN boiler comes equipped with a factory installed
low water cutoff.
ExpansionTank & Air Separator
An expansion tank or other means to control thermal
expansion must be installed in the heating system. An
expansion tank must be installed close to the boiler
on the suction side of the pump. An air scoop and
automatic air vent must also be installed to eliminate air
trapped in the system.
Reverse Return Piping (RECOMMENDED)
Systems using multiple boilers can also be installed
using a reverse return system, Figure 11.
Model
Size
Supply
Size
Return
Size
600 3" NPT 3" NPT
1000 3" NPT 3" NPT
1600 3" NPT 3" NPT
2000 3" NPT 3" NPT
2600 4" NPT 4" NPT
3000 4" NPT 4" NPT

15
Cast Iron Condensing Boilers – Installation Manual
Figure 10 -Typical Single Boiler Piping (RECOMMENDED)
(Circulator pump must be sized for minimum water flow rate of boiler, including system pressure drop)
HIOM-64
Primary/Secondary Piping
Although acceptable, the system is not as cost effective
as reverse return piping. Figure 12 shows a typical
primary/secondary piping system. A dedicated pump is
used to maintain a constant water flow through the
boiler. Systems using multiple boilers can be installed
using a primary/secondary manifold system, Figure 13.
Piping For UseWith Cooling Units
The boiler, when used in connection with a refrigeration
system, must be installed so the chilled medium is piped
in parallel with the boiler.Appropriate valves must be used
to prevent the chilled water from entering the boiler.
When a boiler is connected to a heating coil that may
be exposed to refrigerated air from an air handling
device, the piping system must be equipped with flow-
control valves or some other automatic means of
preventing gravity circulation of the boiler water during
the cooling cycle.
It is essential that following boiler shut off,
the boiler pump continue to operate for
approximately (5) minutes to dissipate the
heat away from the heat exchanger.

16
Cast Iron Condensing Boilers – Installation Manual
Figure 13 -Typical Multiple Boiler Primary/Secondary Piping
Figure 11 -Typical Multiple Boiler Reverse Return Piping (RECOMMENDED)
(Careful consideration as to minimum boiler and system water flow rates must be taken. Please consult our local
manufactures representative for assistance.)
Figure 12 -Typical Single Boiler Primary/Secondary Piping
NOTE: Not all system valves may be shown.Consult local codes for additional system components which may be
necessary. For HeatNet operation, a sensor is required and installed at a minimum of 12" from primary loop tee.
NOTE: Not all system valves may be shown.Consult local codes for additional system components which may be
necessary. For HeatNet operation, a sensor is required and installed at a minimum of 12" from primary loop tee.
NOTE: Not all system valves may be shown.Consult local codes for additional system components which may be
necessary. For HeatNet operation, a sensor is required and installed at a minimum of 12" from primary loop tee.
HIOM-10 REV .6
HIOM-9 REV .4
HIOM-11 REV .4
Motorized
Valve

17
Cast Iron Condensing Boilers – Installation Manual
DOMESTICWATER SUPPLY PIPING
Proper controls must be used to prevent
water supplied for domestic use from
exceeding 130°F, 54°C or a scald injury will
occur! When higher water temperatures are
required for appliances such as a dish-
washer, a mixing valve or some other
tempering means must be installed.
Households with small children may require
water temperatures less than 120°F, 49°C.
Local codes must be complied with!
General Piping Requirements
The KN boiler can be use in combination with an indirect
tank to provide hot water for domestic use. Piping and
components must be suitable for use with potable water.
The indirect storage tank must be equipped with a
temperature and pressure relief valve that complies with
ANSI Z21.22 or CAN-4.4 and CAN-4.6.
The storage tank must be located as close
to the boiler as possible to prevent excessive
head loss which will reduce flow.
ExpansionTank
An expansion tank or other means to control thermal
expansion must be installed in the water heating system
if back flow prevention devices are installed.
Two typical water heating systems are shown in Figures
14 & 15.
Thermostatic MixingValve-Water Above 140°F, 60°C
Water can be stored a temperatures above 140°F,
60°C provided that a thermostatically controlled mixing
valve is used to temper the hot water to an acceptable
temperature before it's supplied for domestic use. The
mixing valve MUST be set to prevent a scald injury from
occurring, see the caution against scalding above.
Storage of water for domestic use above 140°F, 60°C
will provide an increased quantity of tempered water and
help prevent the growth of water born bacteria.
Figure 14 -Typical Single Boiler with Indirect StorageTank Piping
NOTE: Not all system valves may
be shown.Consult local codes for
additional system components
which may be necessary.
NOTES:
1. When using intermittent pump and pump
delay, locate HeatNet sensor with well in
lower 1/3 of tank.Install sensor with heat
sensing compound.
2. Thermal expansion tank may be required,
check local codes.
3. Hot water tank should be equipped with a
combination temperature and pressure relief
valve.Valve shall discharge to a safe place
with an air gap.Refer to local codes.
4. MA Code requires an 1/8" hole in check
valves to compensate for thermal expansion.
5. Boiler and pump purging required. Air must
be purged from 3-way valve after the boiler
is filled. Use purge valves provided.Purge
valve may be located on pump flange. On
multiple boiler installations the flow switch
may fail due to trapped air.See manual for
procedure.
6. Contractor shall verify, with authority having
jurisdiction, for the requirements of an acid
neutralization kit.
Notice:These drawings show suggested piping
configuration, valving and are diagrammatic.
Check with local codes and ordinances for
specific requirements.

18
Cast Iron Condensing Boilers – Installation Manual
Figure 15 -Typical Multiple Boiler with Indirect StorageTank Piping
NOTE: Not all system valves may
be shown.Consult local codes for
additional system components
which may be necessary.
NOTES:
1. When using intermittent pump and pump delay, locate HeatNet sensor
with well in lower 1/3 of tank.Install sensor with heat sensing compound.
2. Thermal expansion tank may be required, check local codes.
3. Common piping must be sized for maximum combined heater flow.
4. Hot water tank should be equipped with a combination temperature
and pressure relief valve.Valve shall discharge to a safe place with
an air gap.Refer to local codes.
5. MA Code requires an 1/8" hole in check valves to
compensate for thermal expansion.
6. Contractor shall verify, with authority having jurisdiction,
for the requirements of an acid neutralization kit.
Notice:These drawings show
suggested piping configuration,
valving and are diagrammatic.
Check with local codes
and ordinances for specific
requirements.

19
Cast Iron Condensing Boilers – Installation Manual
GAS SUPPLY PIPING
Checkthe boilerratingplate tomakesurethat
the boiler is for the type of gas that
will be used. If it isn’t, do not connect the
boilerto thegas supply.Failuretocomplywith
this warning can result in extensive property
damage,severepersonal injury ordeath!
The KN comes from the factory ready to be piped to
the gas supply. If for any reason the boiler is not for the
type of gas available at the installation site, call your
HydroTherm representative to resolve the problem.
Table 8 should be used to ensure that the gas supply
piping is sized properly. If more than one appliance is
supplied by the same supply pipe, the piping must be
sized based on the maximum possible demand.Do not
neglect the pressure drop due to pipe fittings. Table 8
should be used in conjunction with Table 9 to ensure
that the gas supply piping has the capacity to meet the
demand.
Figure 17 depicts the proper way to connect the boiler
to the gas supply piping. The manual shut-off valve
MUST be installed in the supply piping. It should be
installed 5 ft, 1mabove the floor where required by
local codes.Provide a sediment trap at the bottom of the
vertical section of the gas supply pipe upstream of the
gas controls.
A ground joint union should be installed between the
boiler gas controls and the supply piping. Each of these
items are needed to ensure long life and ease of
servicing. Always use a pipe sealant that is suitable for
use with with the type of gas (NG/LP) being used.
Table 8 - Gas Pipe Capacity
Figure 16 - KN Series Condensate Drain
CONDENSATE PIPING
The condensate trap provided with the boiler must be
attached to the bottom pan and piped to a suitable floor
drain (consult local code) or condensate pump. If a
condensate neutralization device is required by local
code, it must be positioned prior to boiler room drain.Fill
thecondensate trapwithwater,checkand maintainwater
level in trap during operation prior to start-up.
Maximum pipe capacity in ft3/hr based on 0.60 specic gravity gas
at a pressure of 0.5 psig or less and a 0.3" WC pressure drop.
Nominal
Iron Pipe
Size
Pipe length in feet
10 20 30 40 50 60 80 100 150
Maximum gas volume of pipe (ft3/hr)
1" 520 350 285 245 215 195 170 150 120
11/4" 1050 730 590 500 440 400 350 305 250
11/2" 1600 1100 890 760 670 610 530 460 380
2" 3050 2100 1650 1450 1270 1150 990 870 710
Note: Multiply the gas volume by 0.62 for propane ow capacity in
ft3/hr. Multiply the propane ow capacity by 2500 Btu/ft3 to determine
the propane Btu/hr capacity for a given pipe size and length.

20
Cast Iron Condensing Boilers – Installation Manual
Never use an open flame to test for gas
leaks. Always use an approved leak
detection method. Failure to comply with
this warning can cause extensive property
damage, severe personal injury or death!
Whenever the gas supply piping is pressure tested
the boiler gas controls must be protected. If the test
pressure is equal to, or less than 1/2 psig, 3.5 kPa
isolate the boiler by closing its' manual shut off valve,
see Figure 17. If the test pressure is greater than, or
equal to 1/2 psig, 3.5 kPa, disconnect the boiler and its
individual shut-off valve.
ELECTRICALWIRING
Electrical Power Connections
Label all wires prior to disconnection when
servicing controls. Wiring errors can cause
improper and dangerous operation! Verify
proper operation after servicing.
ATTENTION. Au moment de l'entretien des
com-mandes,étiquetez tous les filsavantde
les débrancher. Des erreurs de câblage
peuvent entraîner un fonctionnement
inadéquat et dangereux. S'assurer que
l'appareil fonctionne adéquatement une fois
l'entretirn terminé.
The electrical connections to this boiler must be made
in accordance with all applicable local codes and the
latest revision of the National Electrical Code, ANSI /
NFPA-70. Installation should also conform with CSA
C22.1 Canadian Electrical Code Part I if installed in
Canada. Install a separate 120 volt 15 amp circuit for
each KN-6 or KN-10 boiler. Install a separate 230 volt
1Ø with neutral 20 amp circuit for each KN-16, KN-20
boiler, 230 volt 3Ø 20 amp circuit required on KN-26,
KN-30. A properly rated shut-off switch should be
located at the boiler. The boiler must be grounded in
accordance with the authority having jurisdiction, or if
none, the latest revision of the National Electrical Code,
ANSI/NFPA-70.
Line voltage field wiring of any controls or other devices
must use copper conductors with a minimum size of
#14 awg.
Refer to point of connection diagram in back of this
manual and the wiring diagram supplied with the boiler
for proper wiring connections.
Table 9 - Equivalent Pipe Length Chart
Figure 17 - Gas Supply Piping
A lockup style regulator, supplied by others,
must be installed, see Figure 17, if gas
pressure exceeds (14 in WC).The regulator,
when installed as shown, must be installed
at a distance of at least 10 pipe diameters
from the boiler main gas valve.All boilers are
calibrated and factory test fired at
(7 in ± 22) WC.
Aminimumof(2 inWC -KN6, KN10,KN20;3
in WC - KN16, KN26, KN30) and maximum
of (14 inWC) must be maintained to the inlet
of the boiler gas train not to exceed a
maximum of (1 inWC) drop when firing from
minimum input to full load of the gas supply
lineandall the appliances running.
Always use a wrench on the gas valve body
when making gas connections to it. Never
over-tighten the piping entering the gas
valve body or gas valve failure may result!
Safe lighting and other performance criteria were met
with the gas manifold and control assembly provided
on the boiler. All gas connections MUST be leak tested
before putting the boiler into operation.
Nominal
Iron Pipe
Size
Type of pipe tting
90° Elbow Tee1Gas Valve2Gas Cock2
Equivalent pipe length, (ft)
1" 2.6 5.2 0.6 1.5
11/4"3.5 6.9 0.8 1.9
11/2"4.0 8.0 0.9 2.3
2" 5.2 10.3 1.2 3.0
Notes: 1. For ow through branch.
2. For ow at full open.