Install Instructions

Warm Weather Shutdown: In any CH mode utilizing
outdoor reset, the warm weather shutdown feature
prevents the boiler from operating if the outdoor
temperature (read from the outdoor sensor) exceeds
the selected value. The default value for Warm
Weather Shutdown is 70°F (21°C).
Figure 8.3 shows a graphical representation of this value
(vertical line) at 75°F outdoor temperature. This feature
only affects CH demands. The boiler will operate for
DHW demands regardless of outdoor temperature.
4. Other Features:
Pump Post Purge
: The PUREFIRE
®
control allows the
installer to set post purge times for the CH and/or
General Pumps. The circulator will continue to run for
the time selected after the call for heat has ended.
These values are settable from 0 to 900 seconds and
the factory default is 60 seconds.
Ramp Delay Step Modulation
: This feature is useful
for systems with very small zones which can cause a
boiler to short cycle. The Ramp Delay Step
Modulation function only applies to Central Heating
and is not applied to DHW demands.
After the ignition sequence, the control modulates
down to 20% of input. Then the input rate is
gradually increased until the supply temperature
approaches its target. At this time, the control
modulates normally.
Anti-Cycling
: The PUREFIRE
®
boiler control allows the
installer to set a minimum off time to prevent short
cycling of the boiler. This only affects short cycling
due to reaching the temperature limit setpoint. If the
CH or DHW demand cycles, the control will cycle to
match the demand.
“The minimum off time can be set from 0 to 15
minutes in 1 minute increments. It has a default of 3
minutes.
The value for “TDiff” is the difference in temperature
between the supply temperature and the target
temperature that will override the minimum off time.
This temperature difference indicates the presence of
a substantial heat load.”
The default value for TDiff is 30°F and can be set to
values between 20°F and 40°F. TDiff can also be
disabled by choosing “Off”. To do this push the down
arrow until “Off” is displayed.
Maximum CH Input Limit
: The PUREFIRE
®
control
allows the installer to limit the maximum input of the
boiler under a CH load if desired. This can be used
when the boiler is sized primarily for a DHW load and
is oversized for the CH load. This can be set between
50% and 100% and the default is 100%.
CH Response Time
: This feature allows the installer to
adjust the response time of the boiler. The “I” value is
adjustable from 15 to 100 with 15 providing the
fastest response. The default value is 60. If the boiler
achieves its target very quickly with limited
modulation, increase the “I” value to reduce the
response time. If the boiler modulates very slowly to
its target and has problems keeping up with the load,
reduce the “I” value to increase the response time.
BOILER CONTROL: INTERNAL WIRING & OPERATION
Figure 8.3: Outdoor Reset Operation
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