MACH® Series
Gas-Fired Boiler
Installation
Page 23
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.
Analog Input to Adjust Setpoint:
Analog Input Setpoint
0
50
100
150
200
0
1
2
3
4
5
6
7
8
9
10
Voltage
B
o
ile
r
S
e
tp
o
in
t
B oiler Setpoint
Non adjustable Curve
The control must be configured for a remote analog
input setpoint according to the following table:
Item
Parameter
Value
°F
Allowable
Range °F
Maximum Setpoint
4
180
68-185
Minimum Setpoint
5
80
60-140
Boiler Configuration
34
03
The setpoint of the boiler is controlled by an external
0-10 VDC signal. A signal of at least 0.5 VDC is
required to start the boiler. At 0 VDC the setpoint is
32° F; at 10 VDC the setpoint is 212° F. This setpoint
is low and high limited by maximum and minimum
setpoint parameters. The controlled setpoint voltage
range narrows when these limits are used. If the above
tables values are used the boiler setpoint will be 80° F
when the voltage is anything less than approximately
3 VDC. It will then increase linearly with voltage
until approximately 8.5 VDC when it will be 180° F.
The setpoint will remain at 180° F even if voltage is
increased further.
Analog Input to Control Firing Rate:
Analog Input Firing Rate
0
10
20
30
40
50
60
70
80
90
100
0
1
2
3
4
5
6
7
8
9
10
V oltage
F
ir
in
g
R
a
te
The control must be configured for analog input
direct drive by setting parameter 34 to 02.
The firing rate of the boiler is controlled by an
external 0 to 10 VDC signal. At a voltage greater
than 0.5 VDC the boiler turns on and runs at low fire
until 1.8 VDC is reached. The firing rate increases
linearly with voltage until high fire is reached at 10
VDC. The boiler setpoint Parameter 4 remains active
to shut down the boiler when the temperature in the
boiler exceeds this value plus the high temp
differential. These voltage levels, as explained
above, are all “non-adjustable”.
3.12.2 Gas Pressure Adjustment
Note: Adjustments shall only be performed by
service representative specifically trained and
certified to perform maintenance on the
Patterson-Kelley MACH® Series boiler.
See rating plate for the minimum and maximum gas
pressure of the boiler. Each boiler is furnished with a
manual shut-off valve which has an integrated test
port. This port is located on the upstream side of the
