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MACH® Series
Gas-Fired Boiler Installation
Page 25
This port is located on the upstream side of the valve
body for measuring supply pressure. (See figure
below.)
Gas Pressure Test Port
The supply pressure during main burner operation
must be greater than the minimum indicated on the
rating plate (3.5". W.C. for natural gas, 7" W.C. for
propane).
3.12.3 Air Flow Adjustments
The air flow is pre-set at the factory prior to shipment.
In unusual situations the air/gas ratio may have to be
adjusted to obtain proper combustion readings for
specific local conditions.
Combustion measurement instrumentation must be
used to adjust the boiler for local conditions (See
instructions below). Adjust the carbon dioxide (CO
2
)
or oxygen (O
2
) reading to achieve conditions as listed
in the following Table 3-1.
3.12.4 Gas Valve Setup and Adjustment
Note: Verify gas pressure at inlet to boiler is in
accordance with Table 3-1 below. Gas flow is
dependent primarily on fan speed not upstream gas
pressure. When set up for natural gas operation, the
boiler is capable of operating with gas supply pressure
as low as 3.5” W C.
Boiler Test Mode:
The test mode should be used when checking and
setting the gas safety shut off / control valves on the
MACH Series boilers. In this mode an automatic
heat request is simulated as follows:
Test Mode High:
Simultaneously pressing the “Mode” button and the
“+” button for 3 seconds activates the “Test Mode
High” function to drive the boiler output to
maximum. The display will blink and indicate “H” in
the first digit of the display to indicate the boiler is
being driven to the maximum output rating. This test
mode will automatically terminate after 15 minutes or
can be terminated from the control/display panel by
simultaneously pressing the “+” and “-“ buttons for
three seconds.
Test Mode Low:
Simultaneously pressing the “Mode” button and the
“-” button for 3 seconds activates the “Test Mode
Low” function to drive the boiler output to minimum.
The display will blink and indicate “L” in the first
digit of the display to indicate the boiler is being
driven to the minimum output rating. This test mode
will automatically terminate after 15 minutes or can
be terminated from the control/display panel by
simultaneously pressing the “+” and “-“ buttons for
three seconds.
MACH C300 & C450
Required Tools:
2 mm hex wrench
Slotted screwdriver
Combustion analyzer
The MACH C300 and C450 boilers are equipped
with two combined gas/air control and gas safety shut
off control valves. The valves function in parallel
with the variable speed combustion blower to supply
the correct gas air ratio for optimum performance and
efficiency. The combustion blower speed is
controlled automatically and determines the amount
of negative pressure felt at the gas safety shut off /
control valves. The gas valve servo regulators adjust
gas flow for each valve to maintain zero pressure at
the outlet nozzle of the associated valves.
Test Port