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P/N 42-9472 Copyright 2008 Mestek, Inc.
Cast iron condensing boiler
Cast iron condensing boiler
— Control manual
Control menus and adjustments
(continued)
4
Table 8
Setup menus — parameter explanations (continued)
Menu item
Under . . .
Explanation
IA RESET
INDOOR AIR
Activate indoor air reset by setting this to “ON.” Zone wiring must be made to the IAR input
terminals for IAR to operate. See the Boiler manual for details on wiring to the IAR terminals.
AVG TIME
INDOOR AIR
The averaging time (AVG TIME) is the time span over which the control averages the results of
zone demands. Leave this setting at the factory default unless directly otherwise by Mestek
Technical Support.
SET IAR SETPTS
INDOOR AIR
Leave the delta temp settings at factory default settings unless directed otherwise by Mestek
Technical Support. The determine how much the control adjusts maximum allowable fi ring rate
based on its monitoring of zone demand.
OA SHUTDOWN
OUTDOOR AIR
When outdoor air shutdown is enabled (ON), the boiler and its circulating pump shut down
when the outside temperature is above the outdoor air setpoint (OA SETPT). This requires an
outdoor sensor when enabled.
OA SETPT
OUTDOOR AIR
The boiler and its circulator shut down when the outside air temperature is above this setting if
outdoor air shutdown is enabled (ON). This requires an outdoor sensor when enabled.
OA RESET
OUTDOOR AIR
Set to “ON” to enable resetting the boiler outlet temperature (or header temperature) based on
outside air temperature. Set to “OFF” to disable outdoor reset. This requires an outdoor sensor
when enabled.
LOW WATER
@ HI OA
HI WATER
@ LOW OA
OUTDOOR AIR
SET OA SETPTS
These temperatures determine the reset curve for
supply water temperature. High water at low
outside air means the design water temperature
for maximum load (at ODT, or outside design
temperature for the installation). The other end of
the reset curve is the low water temperature at high
outside air temperature. The low water temperature
is generally equal to room temperature, meaning
no heat input to the space would occur below this
outside air temperature.
DELTA ENABLE
PUMP OPTIONS
The boiler pump can be set to run after boiler shutdown to distribute residual heat to the
heating system. Delta enable causes the boiler pump to run until the temperature diff erence
between boiler inlet and outlet is less than DELTA TEMP (see below). The pump will continue to
run an additional period after this for the amount of time specifi ed in PURGE TIME (below).
DELTA TEMP
PUMP OPTIONS
When DELTA ENABLE (above) is set to “ON,” the boiler pump will run until the temperature diff erence
across the boiler is less than DELTA TEMP. (The pump will run an additional time equal to the
PURGE TIME.) An inlet temperature sensor is required.
PURGE TIME
PUMP OPTIONS
The boiler pump can run after boiler shutdown to distribute heat remaining in the boiler water.
PURGE TIME sets how long the boiler pump will run. (Also see DELTA TEMP, above.) NOTICE: For
systems that shut off fl ow valves (such as zone valve systems) when the call for heat is satisfi ed,
this option must be set to “0” to prevent dead-heading the pump.
ALWAYS ON
PUMP OPTIONS
If ALWAYS ON is set to “YES,” the boiler circulator never turns off .
MASTER PUMP
PUMP OPTIONS
If set to “ON,” the master control in the network will keep its pump contacts closed (running
its pump and/or control valve) if no other boilers are operating. This is used to prevent dead-
heading system fl ow.
SETBACK#
NIGHT SETBACK
Setback number is the designator for the setback operation. Up to four (4) setback operations
can be programmed.
