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MACH® Series
Gas-Fired Boiler Installation
Page 23
CAUTION!
Terminal 10 and 11 on TB2 are for pilot duty only.
they should not be connected directly to the
pump.
Outdoor Air Reset (optional):
OUTDOOR AIR vs BOILER SETPOINT
70
80
90
100
110
120
130
140
150
160
170
180
190
0 102030405060708090
OUTDOOR AIR TEMP °F
BOILER SETPOINT °F
The control automatically detects the presence of the
outdoor air sensor. If an outdoor air sensor is present,
the boiler automatically defaults to outdoor air reset
for setting boiler temp. The parameters should be set
according to the following table:
Item Parameter Value
°F
Allowable
Range °F
Maximum Setpoint 4 180 68-185
Minimum Setpoint 5 80 60-140
Outdoor Air
Minimum Temp.
6 20 4-50
Outdoor Air
Maximum Temp.
7 70 59-77
Boiler Shutoff Temp. 10 90 32-140
(32=off)
Outdoor Air Offset 12 0 0-144
Boiler Configuration 34 01
The set point of the boiler is controlled by an outdoor
temperature sensor. As the outdoor temperature falls
the setpoint of the boiler is increased. The boiler
modulates to maintain this setpoint.
The setpoint is adjusted according to the above
parameters. The boiler setpoint will be the maximum
value (180° F) when the outdoor air is at or below a
minimum temperature value (20° F). The boiler
setpoint will be at the minimum value (80° F), when
outdoor air is at or above a maximum temperature
value (70° F). The setpoint for “in between“ values
of outdoor air temperature, is linearly proportional to
the above settings. Using the values in the table
above, the boiler setpoint will be 80° F when the
outdoor air temperature is 70° F. As the outdoor air
temperature drops, the boiler setpoint will be
increased until the outdoor air temperature is 20° F.
At this point the boiler will reach its maximum
setpoint of 180° F. If the outdoor air temp drops
further, the boiler setpoint remains at 180° F.
The boiler shutoff temperature can be used to turn the
boiler off at a given setpoint. For example if you
wanted to shut the boiler off when the outdoor air
temperature was above 65° F you would set the boiler
shutoff temp to 90° F since this is the setpoint that is
called for at 65° F outside air temp.