P-K MACH
®
Gas Fired Boiler
Technical Service 1.877.728.5351
Revised: January 3, 2020
Released: January 3, 2020
Patterson-Kelley 2020
All Rights Reserved.
1004905981 P-K MACH C1500H-C4000 Installation and
Owners Manual (Rev F Jan-2020).docx
Page 46
3.11.2 Manual Control Mode for High and Low Fire Adjustment
To adjust/tune combustion, use the NURO’s “Manual Control Firing Rate” mode. To access this mode,
touch the “Info” button in the lower left corner of the screen, and then press “Service” in the lower left.
Next, touch “Press to Activate Manual Control” which will open the “Manual Control Firing Rate” mode.
This test mode should be used when adjusting or tuning the gas safety shut off/control valve.
Once in “Manual Control Firing Rate” mode, a heat request is required. Once the appliance cycles on
and is running in “Manual Control Firing Rate”, use the UP and DOWN arrows or the slider to force the
boiler to operate at low fire, high fire, or anywhere in-between. To prevent the appliance from cycling
off prematurely during adjustment, ensure that any load devices (air handlers, control valves, radiators,
air handling units, etc.) are in operation and are able to shed/dump the heat created by the boiler.
Recommended Combustion Settings for P-K MACH
®
Boilers
The P-K MACH
®
boilers are equipped with a combination gas/air control and gas safety shut off control
valve. The “zero governor” gas valve responds to the variable speed combustion blower in order to
supply the correct air/gas ratio for optimum performance and efficiency.
Fuel
Nominal
Gas Pressure
High Fire Setting
Low Fire Setting
% O
2
% CO
2
% O
2
% CO
2
Natural Gas
7" W.C.
5.0
+ 0.3
9.1
+ 0
.2
5.1
+
0.3
9.0
+
0.2
Propane Gas
11" W.C.
4.8
+
0.2
10.4
+
0.3
5.0
+
0.2
10.3
+
0.3
NOTE:
Proper water flow should be established before performing any combustion adjustments to
ensure the boiler doesn’t short-cycle or overheat.
NOTICE!
For high altitude adjustments (greater than 2,000 feet above sea level), see
