MACH® Series
Gas-Fired Boiler
Installation
Page 25
Adjustment:
There must be sufficient load to operate the boiler at
high fire to perform the following adjustments.
Required Tools:
TORX
®
T40 wrench and
3 mm hex wrench
Combustion analyzer
Start the boiler and observe proper operating
parameters for the system. The combustion analyzer
probe should be placed in the stack outlet to measure
the combustion parameters.
High Fire Setting
Set boiler to the “Test Mode High”, as described
above, to achieve maximum firing rate of the boiler.
Check combustion readings using the combustion
analyzer. If combustion readings are not in
accordance with Table 3-1, adjust as follows:
Remove the flat, round, blue plastic cap from the
cover. Using a 3mm (or 7/64”) hex wrench, turn the
adjustment screw counterclockwise to increase or
clockwise to decrease gas flow and achieve the desired
CO
2
or O
2
level; see Table 3-1 for correct settings.
(There will be a slight time delay between the
adjustment and the response of the CO
2
/O
2
measuring
instrument. Adjust the settings in small increments and
allow the combustion readings to stabilize before
readjusting. When desired adjustments are complete,
reinstall the blue plastic cap on the cover.
Low Fire Setting
Set boiler to the “Test Mode Low”, as described
above, to achieve minimum firing rate of the boiler.
Check combustion readings using the combustion
analyzer. If combustion readings are not in
accordance with Table 3-1, adjust as follows:
Remove the round metal cap on the gas regulator using
a slotted screwdriver. This will expose the offset
adjustment screw.
Using a TORX® T40 (or 5 mm hex), carefully adjust
the low fire gas setting to achieve the CO
2
/O
2
level
prescribed in Table 3-1.
Note:
The rotation of the Low Fire adjustment is
opposite of the High Fire as follows: Clockwise
rotation increases gas flow, counterclockwise rotation
decreases gas flow.
The offset pressure regulator is quite sensitive and
adjustments should not exceed ¼ turn at a time before
allowing the readings to respond and stabilize.
After proper low fire offset adjustment is made,
reinstall the slotted cap on the regulator.
Following all gas valve adjustments, check for proper
light-off and verify correct fuel/air mix and
combustion quality throughout the entire firing range
(from low to high fan speed).
