ATH HeatNet KN-2 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-
freeairsupply.Follow the instruction manualprocedurestoductairtotheboilerairintake.Iftheboiler has been contaminatedbyoperation
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.
Cast Iron Condensing
Boilers
Models KN - 2 and KN - 4
HeatNet® Manual
KN-2/4-CM2-0714
42-9452
Control Adjustment and Operation Instructions
for Mestek Firmware Version 2.8
Also read and follow:
KN Boiler Manual
KNVent/Air Manual
KN - 2 only

2
KN USER’S CONTROL MANUAL
The KN boiler — HeatNet® control
Control overview
e KN HeatNet control monitors boiler temperature and limit
circuit inputs, modulating boiler ring rate to meet demand.
e control uses microprocessor electronics, watching time-
average response from the system to anticipate how much heat
thesystemneeds.Coupledwiththe ve-to-oneturndown of the
KN boiler, this results in maximum possible condensing-mode
operation. e KN boiler will provide unmatched seasonal
eciency.
Indoor air reset (IAR)
KN’s unique approach to boiler output regulation is its Indoor
Air Reset function. e control monitors the demand from up
to 8 dierent zones. Watching the demand duration and response
to supply temperature, averaging over time, the HeatNet control
anticipates system needs. It sets boiler maximum ring rate and
adjustssupplywatertemperaturetone-tuneboiler heatoutput.
All that is required to enable IAR is to connect thermostat
circuit wires to the IAR inputs. e HeatNet control can also
be congured for outdoor reset operation, but IAR provides
response based on system behavior rather than just looking at
outdoor temperature.
The HeatNet platform
HeatNet controls are designed to provide an integrated boiler
management system on every boiler. e platform provides
multiple levels of selectivity. HeatNet electronics can be
operated as a simple single-boiler control, while still providing
intelligent regulation of boiler ring rate to match system
demand. With a few key strokes on the key pad, the HeatNet
control can operate as a sophisticated multiple-boiler controller,
using simple RJ45 cable interfacing between units. e control
can even accept external control commands from building
managements systems (Modbus standard, with optional bridge
for BACnet or LonWorks) or 20-milliamp analog input from an
external controller.
e control method used by the HeatNet control is based on
digital communications, which eliminates the need for analog
control signals. Analog signal inputs are supported, but a higher
level of control precision, repeatability and feedback is gained
with digital communications.
e HeatNet control can be versatile, providing for operation
in multiple ways:
• Operation as a stand-alone boiler.
• Operation as a boiler in a boiler network, using the on-board
HeatNetprotocol.
• Operation as a member boiler in a boiler management
system.
• Operation as a member of a remotely-controlled boiler
network (20-milliamp regulation).
• Setpoint can be determined by the HeatNet control or by a
20-milliamp input signal.
• Network boilers can be operated by override commands
for increased versatility.
PID response
e HeatNet control uses proportional-integral-derivative
calculations to determine the response to boiler water
temperature changes. is means it not only looks at how far
away the water temperature is from the setpoint temperature,
but how fast the temperature is changing and how it has
respondedovertime.isensurestheboilerwon’tmakesudden
unnecessary changesinringrate.
Multiple boiler operation
e HeatNet control easily interfaces with other HeatNet
controls. Multiple boiler operation using HeatNet protocol only
requires RJ45 cables daisy-chained from boiler to boiler and a
few key strokes seing up control behavior. e master boiler is
automatically selected by connecting a sensor lead to its
HEADER sensor terminals. e HeatNet control recognizes
the sensor and congures the boiler as the master. Other boilers
only need to have an address assigned.
Among the advanced design features of the HeatNet control is
theMOD-MAX seing. is limits thering rateofall boilersto
a pre-set maximum (50% by default). is means all of the
boilers will be run at a very ecient level until all boilers are on.
Only then can ring rate increase above this seing. Boiler
rotationcanberst-on/rst-o,rst-on/last-o,ortruerotation
(the HeatNet control monitors the total on time of all boilers,
and rotates their usage so the total on time is the same for all).
Firmware Version 2.5 and greater is now compatible with
HeatNet Mixed Boiler Systems. For more information on the
operation of HeatNet Mixed Boiler Systems see the KN6-30
HeatNet Control Manual V3.47, which is available at www.
knseries.com.
External limit monitoring
& annunciation
In addition to controlling the boiler, the HeatNet control
monitors external limits wired into the limit circuit connections.
econtrolshuts downthe boiler ifa limit opens,and thedigital
display shows which limit failed. Monitored limits include high
limit aquastat, ow, ignition control fault, inlet pressure, ue
pressure and other optional or user-selectable limits.”

3
KN USER’S CONTROL MANUAL
The KN boiler — HeatNet® control
components
Wiring connections
1. Power wiring, 120 vac
2. Heat demand input
3. DHW demand input
4. Low re terminals
5. High re terminals
6. To boiler outlet water
temperature sensor
7. To optional outdoor
temperature sensor
8. To optional boiler return
water temperature sensor
9. To optional header
temperature sensor
10. To boiler postpurge pump
(factory piped and wired)
11. To boiler circulator
12. Alarm output dry contacts
13. To external high limit and/or
low water cuto if desired
14. To ow switch, when used
15. Used to activate combustion
air damper if desired
16. To combustion air damper proving
switch, required when controlling
combustion air damper
17. Indoor air reset inputs — connect
to up to 8 zone thermostats
18. Optional 20 ma control signal input
19. Remote enable to start when
operating on 20 ma input
20. Optional HeatNet
communications board
21. Boiler wiring socket to blower
and gas valve
22. Boiler wiring socket to pressure
switches and ignition control
23. Boiler wiring socket to
control panel
24. Boiler wiring socket to
control panel
25. Boiler wiring socket to
power switch
26. Boiler wiring socket to transformer
27. Termination DIP switches

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KN USER’S CONTROL MANUAL
1 Method 1: HeatNet modulation – control. . . . . .page 5
• e KN HeatNet control can control up to (16) KN boilers using built-in soware and
hardware.
• Install a RS485 interface on each boiler and connect with RJ45 HeatNet cables
(or shielded wires).
• e header water temperature setpoint can be set by the master boiler or by a 4-20ma
input from an external controller.
• Member boilers can override master boiler control if they receive a contact closure on
the Heat Demand or DHW Demand terminals.
2 Method 2: HeatNet modulation – BMS . . . . . page 14
• is method uses the KN control’s built-in communications capabilities to accept
Modbusprotocolinputs from a buildingmanagementsystem.emasterboiler control
sequences and modulates the boiler network to accomplish the demands from the
building management system.
• Each boiler requires the RS485 interface board and cable, above.
• Boiler setup is essentially the same as for method 1, with the exception that each boiler
must be assigned both a HeatNet network address and an address for the Modbus
interface.
• An additional bus is required to interface with systems using BACnet or LonWorks protocol.
• e master boiler will take control and regulate the boiler network if signal from the
BMS is lost or times out.
3 Method 3: External 4-20ma control . . . . . .page 16
• Up to 5 boilers can be controlled by an external control that provides a 4-20ma input
signal. e external controls must also activate each boiler by closing a contact across
the boiler’s 4-20ma Remote Enable contacts.
• Member boilers can override external boiler control if they receive a contact closure on
the Heat Demand or DHW Demand terminals.
4 Failsafe modes . . . . . . . . . . . . . . . . . . . . . . . . . .page 22
5 Control menus and adjustments . . . . . . . . .page 23
• Operating parameters and control behaviors are set using the KN control’s display/
keypad interface.
• Refer to this section for the menu structure and explanations of the seing options.
6 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . .page 35
7 Communication Registers . . . . . . . . . . . . . . .page 40
Contents
HeatNet
Control panel

5
KN USER’S CONTROL MANUAL
Method 1: HeatNet modulation – local control
1
Overview — control setup sequence
Follow the Boiler manual — Install the boilers according to the KN
Boiler manual before aempting to set up the control system.
1. Install all boilers per the Boiler manual.
2. Close the external gas valve on every boiler.
3. Wire all boilers following the guidelines in this section.
4. Aach a header sensor to the master boiler ONLY. e KN-2 control automati-
cally congures the boiler with a header sensor as the master.
5. Set the master boiler control parameters using its display/keypad.
6. Set the master boiler’s termination DIP switches.
7. Set the termination DIP switches on the member boilers.
8. Set the member boilers’ control parameters using their display/keypads.
9. Follow the instructions in the Boiler manual to start up each boiler before proceeding
further.
10. Finish by connecting cables between the communications boards of all of the boilers
and verifying network operation.
Add communications modules
1. Insert aRS485 communicationsmodule ontoeach ofthe boilers’electrical connection
panels, as shown in Figure 1.
Power supply (120 VAC)
1. See Figure 1 and Figure 2.
2. Connect minimum 14awg copper wire to the power connection as shown in Figure 2.
3. Install a fused service switch, mounted and installed in accordance with all
applicable codes.
Figure 1 Electrical connection board (see item 10,
page 3 for location — Also see the wiring
summary illustrations on the next pages)
Figure 2 120VAC power service terminals on electrical
connection board — See Figure 15 for location
of the power terminal strip
Electrical shock hazard — Disconnect all electrical power
sources to the boiler before making any electrical connections.
Label all wires prior to disconnection when servicing controls.
Wiring errors can cause improper and dangerous operation!
Verify proper operation aer servicing.
Failureto comply with theabovecouldresultin severepersonal
injury, death or substantial property damage.
e 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 to CSA C22.1 Canadian
Electrical Code Part I if installed in Canada. Install a separate
120 volt 15 amp circuit for the boiler. A properly rated shut-
o switch should be located at the boiler. e 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 eld wiring of any controls or other devices must
use copper conductors with a minimum size of #14 awg. Use
appropriate wiring materials for units installed outdoors.

6
KN USER’S CONTROL MANUAL
Method 1: HeatNet modulation – local control (cont.)
1
Figure 3 Wiring the boiler circulator using a circula-
tor relay (required for motors over 1/4 hp)
Figure 4 Wiring the boiler circulator using a relay or
starter (required for motors over 1/4 hp)
Circulator wiring
Postpurge circulator (KN-2 only)
• The circulator shipped installed with the boiler
cannot be used for system circulation. It must be used
as supplied from the factory. It circulates water aer the
boiler stops ring to prevent potential damage from heat
pocketing in the top of the heat exchanger.
• epostpurgecirculatoris factory-piped and pre-wired. Do
not change the usage, the wiring, the location or the piping.
Boiler circulator
• See the Boiler manual for circulator piping.
• Figure 3, Figure 4, and Figure 5 show wiring of the Boiler
circulator (or boiler/system circulator) to the terminal strip
of the KN-2 electrical connection board.
• DO NOT directly connect a circulator with a motor larger
than 1/4 hp. For larger motors, install a circulator relay or
motor contactor . Figure 3 and Figure 4 show the correct
ways to install the boiler circulator using a relay or motor
starter.
(KN-2 only)
Figure 5 Circulator wiring terminal strip (see Figure 1
for location) — Also see the wiring
summary illustrations on the next pages)

7
KN USER’S CONTROL MANUAL
Figure 6 Indoor Air Reset wiring to IAR terminals with
4-wire zone valves and no zone controller
(see Figure 7 for terminal block 6location)
Method 1: HeatNet modulation – local control (cont.)
1
IAR (Indoor Air Reset) wiring, when used
• Heat Demand terminal connections — e end switch leads from the zone valves
must connect to the Heat Demand terminals on the electrical connection board as
shown in Figure 7.
• See Figure 6 for typical wiring to the IAR inputs when using 4-wire zone valves
without a zone controller. For other applications, such as circulator relays or zone
controllers, see Appendix A in the Boiler manual..
Polarity — e connections to the IAR positive terminals (IAR +)
must be to the same location on the zone valve as the thermostat wire, as
shown in Figure A1. e connections to the IAR negative terminals
(IAR –) must be from the zone valve terminal connected to the 24VAC
common line, as shown. Connecting the wires incorrectly can cause the
transformer to be shorted out and damaged. Verify the wiring with a
voltmeter.
Always use a voltmeter to check the leads coming from the end switches
of the zone valves. With the thermostat calling for heat, connect the
voltmeter leads across the wires coming from the end switches. If the
meter shows a voltage reading, the zone valve wires are incorrect.
Change the wiring and retest. DO NOT connect the wires to the boiler
until you have tested as described. Incorrect wiring can damage the
boiler control or other system components.
• If there is only one transformer feeding all of the zone valves in the system, you can
omit the wires to the IAR negative terminals (IAR –) on all but one of the zone
valves. is is because these terminals are jumpered internally on the electrical
connection board. If there is more than one transformer, provide one wire from
each transformer common side to one of the IAR negative terminals (IAR –).
Sensor wiring
• Header sensor is required — A header sensor must be installed in the system
supply piping. Connect the header sensor ONLY to the master boiler. Install
the header sensor in an immersion well. Locate the sensor where it will accurately
sense the system water supply temperature. Connect the sensor leads to the
electrical connection board as shown in Figure 8.
• Outdoor reset application — To operate with outdoor reset, purchase and
install an outdoor sensor. Mount the sensor such that it is shielded from direct
sunlight if possible and not likely to be covered by snow dris or debris. Connect
the outdoor sensor leads to the master boiler’s electrical connection board as
shown in Figure 8. (Member boilers could have their own outdoor sensor if they
will be operated in override mode by closing the Heat Demand terminals.)
• Return water temperature sensor — e return water temperature sensor is
optional, only needed if you want to automatically control the boiler postpurge
pump cycle time. Install the sensor in a well in the boiler return piping. Connect
the sensor leads to the electrical connection board as shown in Figure 8, e
Return water sensor can OPTIONALLY be used as a DHW sensor. e control
would then regulate to this sensor for DHW demands. When used in this way the
sensor must be moved to a position where it will sense the temperature of the
water being supplied to the tank. For more information see the DHW SENSOR
description in Table 8.
• Sensor wiring, return water temperature sensor —Firmware Version 2.5
and greater monitors the temperature dierential (Delta T) across the heat
exchanger. If the Delta T exceeds the seing, the input to the boiler can be
optionallylimited.
DHW wiring
• To operate the boiler for domestic water heating with a storage tank, install and pipe
the tank according to the tank manufacturer’s instructions and the recommended
piping diagrams in this manual. Consult the factory for applications not covered.
• e circulator used for DHW must be operated by a circulator relay or zone
controller that is activated when the tank aquastat calls for heat, as shown in
(Figure7-terminal#2).
• Connect the tank enable terminals across the DHW DEMAND terminals on the
master boiler’s electrical connection board as shown in Figure 7. (Member boilers
could be connected to tank aquastats if they are piped appropriately and intended
to operate in override mode.)

8
KN USER’S CONTROL MANUAL
Figure 7 KN wiring summary — wiring to electrical connection board
Method 1: HeatNet modulation – local control (cont.)
1
Also see Figure 2.
J9 Control Inputs
(Connect remote temperature control 4-20mA input wires here
when remote setpoint
is required. The setpoint temperature
will be set by the 4-20mA signal. The corresonding setpoint
values can be set in the 4-20mA INPUT menu.)
Master boiler: Room thermostats,
end switches or relay contacts
(Connect thermostat, zone valve end switches,
or remote start relay contact here. Test when done
to ensure no stray voltage is present on any of the
wires. See the Boiler manual for procedure.)
Master boiler: Connect override contacts only
(Individual boilers, if piped appropriately, can be
activated for override operation, such as DHW
heating or emergency space heating.)
The boiler is shipped with a
jumper across the HEAT DEMAND
terminals. Remove this jumper
when using a thermostat or other
external control to start the boiler.
Tank
Aquastat
GND
DHW Relay
50VA
120VCom
24VAC
24V
Com
RI
DHW Pump Motor
JI4
15
120VAC
Supplied, mounted and wired by installer
Wire Harness 70-2043
Factory Wiring — Do Not Change

9
KN USER’S CONTROL MANUAL
(KN-2 only)
Note: For multiple boilers with a single combustion air damper
Figure 8 KN wiring summary — wiring to electrical connection board, continued (see Figure 7 for terminal strip locations)
Also see Figure 5.
Method 1: HeatNet modulation – local control (cont.)
1

10
KN USER’S CONTROL MANUAL
External interlocks
1. Wire external limits and ow switch, when used, as shown in Figure 8.
2. If wiring to and from a motorized combustion air damper, follow the guidelines
given in Figure 8. Connect only to the master boiler.
If any of the member boilers is to operate in override mode, and the
system is equipped with a combustion air damper, you must provide
special wiring in order to ensure the damper opens and proves when
the boiler res. is must be done without compromising the wiring
between the master boiler and the damper.
Overrides — Control priorities
3. e KN control can provide override operation for any or all member boilers in
a HeatNet network. is requires the boilers be piped with appropriate isolation
piping and controls.
4. Override is done by closing a contact across the Heat Demand or DHW Demand
terminals of any boiler. ese priority inputs override all network controls or
4-20mA input controls to the boiler.
5. DHW Demand — e DHW Demand closure takes priority for ALL boilers,
including the master and all members. When DHW Demand closes, the boiler
or boilers immediately switch to DHW operation, including seing the water
temperature to the DHW Setpoint.
6. Space heating, Heat Demand — If any member boiler sees closure across its
Heat Demand terminals it will begin operation in space heating mode indepen-
dently of commands from the master boiler or 4-20mA input source.
Do not wire boilers for override operation unless the piping design
provides automatic isolation of the overriding boilers. e master
boiler would be unable to properly control system water temperature
if member boilers were to input heat to the system without control
from the master. DHW operation, in particular, would raise the supply
temperature from overriding boilers to the DHW Setpoint.
Override operation control setup — Boilers must be set up with
operating parameters necessary during their override operation; i.e.,
local setpoint, DHW setpoint, etc.
7. Summary — priority sequence is:
Priority 1 = DHW Demand
Priority 2 = Heat Demand
Priority 3 = HeatNet input
Set termination DIP switches
1. e HeatNet network needs to recognize the beginning and end of the
network. is requires seing the four DIP switches on each boiler’s electrical
connection board.
2. See Figure 9 for location of the switches.
3. See Table 1 for required seings. e table gives seings for HeatNet modulation
— local control and for remote control from a building management system
(Modbus protocol).
4. DO NOT connect the communications cables (or shielded wires) between boilers
until all boilers have had parameters set and then been started up following all
instructions in the KN Boiler manual.
Figure 9 Termination DIP switches (see item 7, Figure 7
for location)
Table 1 Termination DIP switch settings
Boiler HeatNet Modbus
(see note)
Master Switch 1: ON
Switch 2: ON
Switch 3: OFF
Switch 4: OFF
Switch 1: ON
Switch 2: ON
Switch 3: ON
Switch 4: ON
Last member Switch 1: ON
Switch 2: ON
Switch 3: OFF
Switch 4: OFF
Switch 1: ON
Switch 2: ON
Switch 3: OFF
Switch 4: OFF
Other members Switch 1: OFF
Switch 2: OFF
Switch 3: OFF
Switch 4: OFF
Switch 1: OFF
Switch 2: OFF
Switch 3: OFF
Switch 4: OFF
Note: Modbus setup is for applications controlled by a building management system. For
systems using BACnet or LonWorks, a bridge board is used to interface with the KN-2
control. e switch is “on” when in the down position and “o ” when in the up position.
Method 1: HeatNet modulation – local control (cont.)
1