Patterson-Kelley MACH-05 Air Flow Adjustments, Gas Valve Setup and Adjustment, MACH C300 & C450

MACH® Series Gas-Fired Boiler Installation

This port is located on the upstream side of the valve body for measuring supply pressure. (See figure below.)

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 Port

Gas Pressure Test Port

Test Mode Low:

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 (CO2) or oxygen (O2) 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.

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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.