PeerlessBoilers Peerless PureFire PFC-460, Инструкция по установке, эксплуатации и обслуживанию

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a. Setpoint Operation: When using a setpoint
strategy, the boiler targets a fixed setpoint which is
set in the User Menu on the
P
URE
F
IRE
® 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 P
URE
F
IRE
® , 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.
•
Mode 0, Indoor Thermostat : This is the default
mode in which the boiler responds to a
demand from an indoor thermostat or zone
control panel at terminals #1 and #2 in the
P
URE
F
IRE
® control panel. The control targets a
fixed setpoint and as the boiler water
temperature approaches the target, the control
begins to reduce the fuel input. This mode
doesn’t require an outdoor sensor.
•
Mode 1, Indoor Thermostat with Outdoor Reset :
When operating in this mode, the control uses the
outdoor temperature and installer selected data to
calculate a target boiler water temperature. A
detailed description of outdoor reset is presented
later in this section.
•
Mode 2, Permanent Demand and Outdoor
Reset
: In this mode, the boiler operates to
maintain a supply (header) temperature
calculated by the outdoor reset algorithm.
The boiler operates independently of any
room thermostats. This is useful in buildings
with many zones which operate on
independent thermostats to prevent the boost
function (described later in this text) from
increasing the target temperature due to a long
sustained call for central heat resulting from
overlapping individual calls.
•
Mode 3, Permanent Demand : This mode is
similar to Full Outdoor Reset except that the
control targets a fixed setpoint instead of a
calculated setpoint based on the outdoor
temperature. Again, the boiler control operates
independently of input from room thermostats.
If a switch between terminals #1 and #2 is
closed, the target temperature will be set back
by 18°F (10°C).
•
Mode 4, 0 -10V Input to Modulate Setpoint :
This allows the boiler supply target to be set by
an external analog 0-10 volt signal. The input
for this signal is at terminals #15 & #16. A call
for heat will be generated by a signal of 1.5
VDC or higher. The setpoint for an input voltage
between 1.5 and 2.0 VDC will result in a boiler
setpoint of 68°F (20°C). An input voltage of 10
VDC will result in a setpoint of 195°F (91°F).
•
Setback : If a switch is closed across terminals
#1 & #2, a setback of 18°F (10°C) is applied
to the calculated target temperature. This
feature is useful in a building (such as an office
building) that is unoccupied during certain
times. A switch or timer can be used to set
back the boiler target temperature during
unoccupied periods.
d. Pump Purge Time: The installer can define the
length of time that the circulators operate after the
end of call for heat. The CH and General circulator
post purge time can be set independently. The
following chart shows the range and default values
for both of these pumps.
Table 8.17: CH Modes
Mode Display
Target
Temperature
Action when
Terminals #1 &
#2 Closed
0
Indoor
Thermostat
Fixed Setpoint
Call for Central
Heating
1
Indoor
Thermostat
with OD Reset
Outdoor Reset
Calculation
Call for Central
Heating
2
Permanent
Demand & OD
Reset
Outdoor Reset
Calculation
18°F (10°C)
Target Setback
3
Permanent
Demand
Fixed Setpoint
18°F (10°C)
Target Setback
4
0-10 V Input
to Modulate
Setpoint
External Analog
(0-10 VDC) Input
of Setpoint
No Effect
Figure 8.29: CH Settings – CH Modes
Figure 8.30: CH Settings – Pump Purge Time
Table 8.18: Pump Purge Time Ranges & Defaults
Circulating Pump Minimum Default Maximum
Central Heating (CH) 0 1 minute 60 minutes
General 0 1 minute 60 minutes
BOILER CONTROL: OPERATION