Patterson-Kelley MOD-04 User Manual

Page 24

Modu-Fire

Gas-Fired Boiler

Installation

3.12.3 Gas Pressure Adjustment

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”
IPS). The supply pressure during main burner op-
eration must be greater than the minimum indicated
on the rating plate. The second tap is located down-
stream from the last main gas control in the union
elbow where the gas line enters the back of the
cabinet and is for measuring the manifold gas pres-
sure (1/8” I.P.S.)

Gas Pressure Adjustment

To adjust the gas pressure, remove the cover plate
from the air / gas ratio control valve. Set the boiler
at High fire as described in the boiler operation sec-
tion of the manual. The High fire gas pressure is
adjusted with the lower screw of the air / gas ratio
control vale. Using a combustion analyzer, adjust
the oxygen reading between 6.5% and 7.5%. Set the
boiler at Low fire as described in the boiler opera-
tion section of the manual. For initial adjustment
the cabinet pressure should be the same as shown on
the “Factory Firetest” label. The Low fire gas pres-
sure is adjusted with the upper screw of the air / gas
ratio control valve. Using combustion measurement
equipment, adjust the oxygen reading between 6.5%
and 7.5%.

Run the firing rate up and down through the com-
plete firing range and verify that the oxygen read-
ings are within the proper range.

Low-fire Adjustment

High fire Adjustment

BASIC COMBUSTION ADJUSTMENT PROCEDURE

Start boiler in test mode

Adjust start pressure with orange cam 1.0” – 1.2” H2O cabinet air

Adjust pilot gas for good pilot – See factory run out label

Start boiler and measure combustion O2 between 6.0 – 8.0

Ramp to high fire adjust cabinet air to nameplate with red cam. Combustion O2 between 7.0 – 7.5.

Ramp to low fire 0.3” adjust cabinet air with blue cam

Check high fire and low fire again