HydroTherm KN-2 Use and maintenance 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 instructionmanualprocedurestoductairtotheboilerairintake. 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.
P/N 42-9452 8/08 Copyright Hydrotherm
Cast iron condensing boilers
Models KN
- 2 and KN - 4
Cast iron condensing boilers
Models KN
- 2 and KN - 4
Control manual
Control adjustment and
operation instructions
Control manual
Control adjustment and
operation instructions
Also read and follow:
KN Boiler manual
KN Vent/air manual
Also read and follow:
KN Boiler manual
KN Vent/air manual
KN-2/4-CM2-808
KN
Series

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KN USER’S CONTROL MANUAL
The KN boiler — HeatNetTM 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 the system needs. Coupled with the ve-to-one turndown 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)
Hydroerm’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 adjusts supply water temperature to ne-tune boiler heat output. 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 HeatNet protocol.
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.
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 responded over
time. is ensures the boiler won’t make sudden unnecessary changes in ring rate.
Multiple boiler operation
e HeatNet control easily interfaces with other HeatNet controls. Multiple boiler operation usingHeatNet
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 the MOD-MAX seing. is limits the
ring rate of all boilers to 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
rotation can be rst-on/rst-o, rst-on/last-o, or true rotation (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).
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HeatNet
Control panel

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

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KN USER’S CONTROL MANUAL
The KN boiler — with HeatNetTM control

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KN USER’S CONTROL MANUAL
1 Method 1: HeatNet modulation – control. . . . . .page 6
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
Modbus protocol inputs from a building management system. e master boiler con-
trol 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 in-
terface.
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 Control menus and adjustments . . . . . . . . .page 22
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.
5 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . .page 31
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Contents
HeatNet
Control panel

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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.
Install all boilers per the Boiler manual.
Close the external gas valve on every boiler.
Wire all boilers following the guidelines in this section.
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.
Set the master boiler control parameters using its display/keypad.
Set the master boiler’s termination DIP switches.
Set the termination DIP switches on the member boilers.
Set the member boilers’ control parameters using their display/keypads.
Follow the instructions in the Boiler manual to start up each boiler before proceeding
further.
Finish by connecting cables between the communications boards of all of the boilers
and verifying network operation.
Add communications modules
Insert aRS485 communicationsmoduleonto each oftheboilers’electricalconnection
panels, as shown in Figure 1.
Power supply (120 VAC)
See Figure 1 and Figure 2.
Connect minimum 14awg copper wire to the power connection as shown in Figure 2.
Install a fused service switch, mounted and installed in accordance with all appli-
cable codes.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
1.
1.
2.
3.
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.
Failuretocomplywith 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.

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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 can-
not 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 pocket-
ing in the top of the heat exchanger.
epostpurgecirculator is factory-pipedandpre-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.
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(KN-2 only)
Figure 5 Circulator wiring terminal strip (see Figure 1,
page 6, for location) — Also see the wiring
summary illustrations on the next pages)

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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, page 9 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, page 9.
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
sensethe systemwatersupplytemperature. Connect the sensorleadstotheelectri-
cal connection board as shown in Figure 8, page 10.
Outdoor reset application — To operate with outdoor reset, purchase and in-
stall an outdoor sensor. Mount the sensor such that it is shielded from direct sun-
light 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, page 10. (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, page 10.
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 con-
troller that is activated when the tank aquastat calls for heat.
ConnectthetankaquastatterminalsacrosstheDHWDEMAND terminalsonthe
master boiler’s electrical connection board as shown in Figure 7, page 9. (Member
boilers could be connected to tank aquastats if they are piped appropriately and
intended to operate in override mode.)
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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, page 6.

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KN USER’S CONTROL MANUAL
(KN-2 only)
Figure 8 KN wiring summary — wiring to electrical connection board, continued (see Figure 7, page 9, for terminal strip locations)
Also see Figure 5, page 7.
Method 1: HeatNet modulation – local control (cont.)
1