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P/N 42-9534 8/08 Copyright 2008 Hydrotherm
KN-SERIES GAS-FIRED DIRECT VENT CAST IRON BOILERS – CONTROL MANUAL
1 Stand-alone boiler . . . . . . . . . . . . . . . . . . . . . . . page 6
Provide an external contact connected across J12A HEAT DEMAND terminals
to start the boiler. (A MEMBER boiler in a network can also be activated by closing
the circuit across HEAT DEMAND.)
Th
e boiler can operate based on its SUPPLY temperature, or can be operated by remote
control from a 4-20mA source. And setpoint temperature can be controlled locally
or by 4-20mA signal from a remote source.
Th e boiler’s T1/T2 terminals can be used to operate the boiler as two-stage (fi red
at minimum input or maximum input).
Th e AA terminals can be used to fi re the boiler as ON/OFF at maximum input.
2 Multiple boilers: HeatNet modulation . . . . . page 8
Th e
KN
HeatNet control can control up to (16)
KN
boilers using built-in soft ware
and hardware.
KN
boilers come standard with HeatNet communications capability, and require
only RJ45 HeatNet cables (or shielded wires) to connect between them.
Th 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 terminals or the AA high fi re terminals. In addition, the
controls can be set up to allow priority override by a remote 4-20mA source.
3 Multiple boilers: BMS operation . . . . . . . . .page 13
Combined BMS/HeatNet operation — Th
is method uses the
KN
control’s built-in
communications capabilities to accept MODBUS protocol inputs from a building
management system. Th
e master boiler control sequences and modulates the boiler
network to accomplish the demands from the building management system.
Direct BMS control of all boilers — Each boiler can be operated directly by the
BMS (each boiler will require an optional bridge if using BACnet or LONWORKS).
Boiler setup is essentially the same as for method 2, with the exception that each
boiler must be assigned both a HeatNet network address and an address for the
MODBUS interface.
An additional bridge is required to interface with systems using BACnet or LON-
WORKS protocol.
Th e master boiler will take control and regulate the boiler network if signal from
the BMS is lost or times out.
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The Mestek
KN
boiler — with HeatNet
TM
control
KN
HeatNet
Control panel
