17
P/N 42-9534 8/08 Copyright 2008 Hydrotherm
KN-SERIES GAS-FIRED DIRECT VENT CAST IRON BOILERS – CONTROL MANUAL
Wiring
(continued)
5
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 the
KN
Series Gas Boiler Installation & Oper-
ating Instructions
manual
. Consult the factory for applica-
tions not covered.
If using the SYS/DHW HEADER sensor in the DHW
tank, the DHW circulator should be activated using the
SYSTEM CIRCULATOR terminals on the electrical con-
nection board.
External interlocks
If used, wire external limits and fl ow switch, as shown in Fig-
ure 6, page 20.
If wiring to and from a motorized combustion air damper
(or dampers), follow the guidelines given in Figure 6,
page 20. Connect only to the master boiler. Make sure the
AUX FUNCTION options are set correctly.
If any of the member boilers is to operate in
override mode, and the system is equipped with
a single, master combustion air damper, you
must provide special wiring in order to ensure
the damper opens and proves when the boiler
fi res. Th is must be done without compromising
the wiring between the master boiler and the
damper.
Overrides — Control priorities
Th e
KN
HeatNet control can provide override operation
for any or all boilers in a HeatNet network. Th is requires
the boilers be piped with appropriate isolation piping and
controls as needed for isolation.
Do not wire boilers for override operation unless
the piping design provides automatic isolation of
the overriding boilers. Th 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.
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•
1.
2.
1.
Override operation control setup — MEMBER boilers must be set
up with operating parameters necessary during their override (local)
operation.
A
KN
HeatNet boiler will respond to overrides in the following order. Th
e modes
listed will override any other activation function listed below it.
Figure 3
Boiler input priorities
MASTER BOILER
MEMBER BOILER
Priority 1
AA terminals
ON/OFF operation
Master boiler operates in ON/OFF
and fi res all member boilers ON/OFF
together based on system sett ings.
See Figure 8, page 22 for wiring
connections.
Priority 1
AA terminals
ON/OFF operation
Member boiler switches to local control
in ON/OFF operation, using the boiler’s
sett ings.
See Figure 8, page 22 for wiring
connections.
Priority 2
HEAT DEMAND
Master boiler operates in full modulation
and fi res/modulates member boilers
based on system sett ings.
Priority 2
HEAT DEMAND
Member boiler switches to local control,
using the boiler’s sett ings for operation
and modulation.
Priority 3
HeatNet input
Member boiler receives operating
commands fr om the master boiler
through the cable or shielded wires
between HeatNet boilers.
Priority 3
4-20mA/0-10VDC input
Requires closure across the 4-20mA
ENABLE terminals.
Master boiler operates and controls
member boilers based on 4-20mA
signal received at master.
Priority 4
4-20mA/0-10VDC input
Requires closure across the 4-20mA
ENABLE terminals.
Member boiler operates on local
control based on 4-20mA signal
received at member.
Sett ing the 4-20mA parameter to HIGHEST in the ADVANCED
SETUP menu will cause 4-20mA ENABLE to move to priority 1.
Priority 4
T1/T2 stage control
Master boiler operates based on closure
of T1 and T2 terminals on master, fi ring
member boilers at the same rate.
See Figure 8, page 22 for wiring
connections.
Priority 4
T1/T2 stage control
Member boiler operates on local control
based on closure of T1 and T2 on
member boiler.
See Figure 8, page 22 for wiring
connections.
1.
