Midco HMA-2 & HMA-2A Series - Manual (Page 13)

Midco International Inc.
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Burner Trouble Shooting
The Midco Burner is only a component of the complete system. For trouble shooting of the
equipment contact the OEM (Original Equipment Manufacturer) or the component manufacturer.
If the pilot fails to light: install a manometer on the pilot pressure tap. Check for 3.5″ W.C. for
natural gas or 2″ W.C. for propane, using a natural gas pilot or 5″ to 7″ using a propane pilot with
orifi ce # 4957-07 (#58 Drill .042). If no gas check for voltage to pilot solenoid valve. If no voltage
check operating controls or primary fl ame safeguard. If voltage to pilot solenoid valve is present
and if there is 3.5″ W.C. gas pressure at pilot pressure tap then check for spark or fl ame rod
settings. See Figure 7. If there is no voltage to pilot solenoid valve, refer to Flame Safety control
specifi cations or contact the original equipment manufacturer.
If Main Burner fails: If no main fl ame check manifold pressure. If no manifold pressure check for
voltage to the gas solenoid valve and check if main manual fi ring valve is open. If no voltage to gas
valve refer to Flame Safety control specifi cations or contact the original equipment manufacturer.
If the pilot fails as main gas valves open, the fi rst adjacent gas port hole (next to the pilot) might
need to be plugged with furnace cement. For high fi re start units see Figure 7 - Pilot Confi guration.
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Annual maintenance of HMA 2 & HMA 2A burner is recommended to ensure trouble free operation.
Direct Gas-Fired Heater Burner Maintenance
1. Clean the burner plates
2. Clear the burner gas and air ports
3. Change the spark rod igniter
4. Insure the fl ame sensor is in good condition
Use a stiff wire brush to clean the burner plates. Scrub both sides of the stainless steel burner plates
to remove any soot or other crud, which may be on the burner. All of the burner plate holes must
be clear so air can pass through them unrestricted. The holes in the burner plate allow air to mix
with the gas in increasing amounts, as the fl ame gets longer. Scrub the rust, soot and other foreign
material from the burner orifi ce area. After the burner plates are cleaned inspect them for cracking.
Cracks occurring between one or two holes are normal and should be of no concern. If the cracking
is more extensive, the affected plates should be replaced. Clean the burner gas and air ports using a
drill or piece of wire of the appropriate size. See the Table 5 for drill size. After the orifi ces are drilled
to the correct size and using compressed air or a vacuum, remove any debris from the manifold.
Debris left in the manifold will prematurely clog the orifi ces in the future.
Gas Port Air Port
Burner Section and Gas Type Drill Size Decimal Drill Size Decimal
Wire Gauge Wire Gauge
HMA 2 Natural / Propane 1/8″ .125 43 .089
HMA 2A Natural / Propane 1/8″ .125 42 .093
Table 5 - Drill Sizes for HMA 2 / 2A
After the burner plates and orifi ces are cleaned inspect the spark rod. The tip should be clean and
free of dirt and carbon. The porcelain must be intact. If it is cracked, replace it. Pull the fl ame rod or
ultraviolet scanner as well. If the fl ame sensor is a scanner, clean the lens with a clean damp soft
rag. The fl ame rod’s metal rod should be clean and free of dirt and carbon. Like the spark rod igniter,
the porcelain on the fl ame rod must be intact as well. Replace it if it is cracked.
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Burner Maintenance