45
k. Maximum Fan Speed: The maximum fan speed
adjustment is intended to compensate for long
exhaust vent runs if the boiler fails to keep up with
the required load. Since the input rate may drop
off slightly under increased resistance due to long
exhaust vent installations, the boiler input may be
incrementally increased to compensate. This
adjustment should only be made if both of the
following conditions are met:
•
The boiler is not keeping up with the required
load.
•
The input rate has been determined to be below
the rated input by timing the gas supply meter.
If these conditions are not met, contact your
Peerless
®
Representative for assistance.
l. Alarm Mode
: The alarm mode allows the installing
contractor to set the menu to the mode
appropriate for the installation. The default setting
is “Stand Alone” in which the alarm contacts
(Terminals #31 & #32) simply close if an alarm
condition exists. Figure 8.31 shows the proper
wiring arrangement for the “Common Vent” alarm
mode. In this configuration, the alarm will sound if
a boiler loses power.
4. Central Heating (CH) Settings
CH settings manage the boiler temperature and
circulators for the central heating load. Although the
menu items that follow are factory set, by default, to
values that can operate in any installation, they can
be adjusted to maximize the efficiency of this product.
The boiler can be configured to operate with a fixed
setpoint or using outdoor reset to vary the boiler
target temperature according to the load implied by
the outdoor temperature.
a. Setpoint Operation
: When using a setpoint
strategy, the boiler targets a fixed setpoint which is
set in the User Menu on the P
UREFIRE
®
control. As
the boiler supply (outlet) temperature approaches
this target, the burner begins to modulate the fuel
input, reducing the output rate of the boiler. If the
boiler reaches a temperature of 9°F (5°C) above
the setpoint before the heat demand ends, the
burner will shut down. If the heat demand
continues and the boiler temperature drops 9°F
(5°C) below the setpoint, the burner will restart.
b. Outdoor Reset Operation
: Outdoor reset strategies
are ideal for condensing boilers for two reasons:
•
Heat distribution units, such as radiators,
radiant floors and copper baseboard are sized
to deliver the heat required on the coldest day
at a set temperature. For the remainder of the
heating season, the maximum output is not
required, so the distribution can be set to a
cooler temperature.
•
Condensing boilers, like the PUREFIRE
®
, are
designed to withstand acidic condensate and
therefore can be operated at as low a
temperature that is reasonable. At lower
temperatures [below 120°F (49°C) return
temperature], these boilers condense more
and are more efficient.
c. CH Modes
: The CH modes allow the operator to
change the way the boiler operates to satisfy
central heating demands.
BOILER CONTROL: OPERATION
Table 8.14: Air Adjustment Ranges & Defaults
Parameter Default Minimum Maximum
Air Adjustment
Min Fan Speed
0 rpm 0 rpm 540 rpm
Air Adjustment
Max Fan Speed
0 rpm 0 rpm 540 rpm
Figure 8.31
Figure 8.30: Burner Settings – Alarm Mode
Managing Burner Only
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