Page 22
KN INSTALLATION AND OPERATION INSTRUCTIONS
Wiring single boiler
(continued)
7
Figure 20
Indoor Air Reset wiring to IAR terminals with
4-wire zone valves and no zone controller
(see Figure 21a for terminal block
6
location).
Sensor wiring
No sensor wiring is necessary unless
:
•
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 drifts or debris. Connect
the outdoor sensor leads to the electrical connection board as shown in Figure 21b,
page 24.
•
Header sensor application
— As shown in the piping diagrams in this manual,
a header sensor is needed if the boiler supply temperature may be different from
the header temperature. If required, purchase and install a 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 21b, page 24.
•
Return water temperature sensor
— The return water temperature sensor
is optional, only needed if you want to automatically control the boiler postpurge
pump cycle time. To use the return water temperature sensor, purchase and install
the sensor in a well in the boiler return piping. Connect the sensor leads to the
electrical connection board as shown in Figure 21b, page 24.
IAR (Indoor Air Reset) wiring, when used
• Heat Demand terminal connections — The end switch leads from the zone valves
must connect to the Heat Demand terminals on the electrical connection board as
shown in Figure 20 and Figure 21a.
• See Figure 20 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 this manual. Also see the Control manual.
Polarity
— The 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. The 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. This 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 –
).
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 recom-
mended piping diagrams in this manual. Consult the factory for applications not
covered.
• The circulator used for DHW must be operated by a circulator relay or zone
controller that is activated when the tank aquastat calls for heat.
• Connect the tank aquastat terminals across the DHW DEMAND terminals on
the electrical connection board as shown in Figure 21.