Patterson-Kelley Thermific, Installation & Owner'S Manual

Page: 20 / 46

Thermific
®
Gas-Fired Boiler Installation
Page 16
I mportant: After initial programming, altering the set
point for stage 1 up or down will result in a change in
set point 2 by the same number of degrees and in the
same direction. If increasing or decreasing the set
point for stage 1 results in exceeding the control limits
(-40' to +220º F) for stage 2, the control will not allow
the user to enter a value for stage 1 higher or lower
than this limit.
3.12.2 Gas Pressure Adjustment
Increase Decrease
Gas Pressure Regulator
See rating plate for the minimum and maximum gas
pressure of the boiler. Each boiler is furnished with
two plugged taps in the gas manifold for test gauge
connections. One tap is located at the main gas cock
for measuring the gas supply pressure (1/4" I.P.S.).
The supply pressure during main burner operation
must be greater than the minimum indicated on the
rating plate (4 in. W.C. for natural gas, 7 in. W.C. for
propane). The second tap is located downstream from
the last main gas control at the elbow where the gas
line enters the back of the cabinet and is for measuring
the manifold gas pressure (1/8" I.P.S.).
If a replacement Lo-Hi-Lo actuator is required, follow
manufacturers instructions and pre-set the Lo fire set-
ting of the actuator the same as the original actuator.
This must be performed by qualified service person-
nel.
To adjust gas pressure, first connect appropriate pres-
sure-sensing device at the manifold tap, then remove
seal cap from regulator. Turn adjusting screw clock-
wise to increase pressure, counter-clockwise to de-
crease pressure. The manifold gas pressure on the
"Rating Plate," on the back of the cabinet, is provided
only as a guide to the proper setting. The manifold gas
pressure indicated on the "Factory Firetest" label (af-
fixed on the back of the cabinet) should be used to
achieve the proper firing rate of the individual boiler.
Replace seal cap after adjustment.
Important: Never underfire low fire (Lo-Hi-Lo
only).
3.12.3 Air Flow Adjustments
The air flow is pre-set at the factory prior to shipment.
The air (and gas) may have to be adjusted for local
conditions.
All air flow adjustments must be performed by quali-
fied service personnel.
For initial light off, adjust the air flow until the cabinet
pressure is the same as shown on the "Factory Firetest"
labels.
Combustion measurement instrumentation must be
used to adjust the boiler for local conditions (See in-
structions below). Adjust the carbon dioxide (CO
2
) or
oxygen (O
2
) reading corresponding to approximately
50% excess air.