Midco HMA-2 & HMA-2A Series - Manual (Page 12)

12
Midco International Inc.
8471 34
3. For intermittent, or interrupted ignition systems. See Figure 5a for typical piping.
a. Pipe the pilot gas supply line up stream of the main gas valve.
b. With the unit running adjust the pilot pressure regulator to 3.5 inch W.C. for natural gas
or 2.0 inch W.C. for propane gas. Using a natural gas pilot or 5″ to 7″, using a propane
pilot with orifi ce # 4957-07 (#58 Drill .042)
4. For direct spark ignition system when using a pilot for ignition. See Figure 5b.
a. Pipe the pilot gas supplied line to the main gas line downstream of the main gas valve.
5. Pilot ignition
a. Make sure the main gas valve to the burner is closed for intermittent or interrupted
ignition.
b. Observe the pilot fl ame, the fl ame should be blue and should extend approximately to
half of the burner end plate.
c. Check the fl ame signal.
d. Flame signal should be between 2-5 UA or 2-5 VDC
6. Depending on the pilot confi guration make following adjustments, if required.
a. For Spark rod and fl ame rod confi gurations
Make sure the fl ame rod is pointing towards burner manifold.
Make sure the fl ame rod is not touching baffl es or burner manifold.
Make sure the spark rod is positioned above the pilot gas tube and that it will spark to
the end of the gas tube. See Pilot Detail Drawings for this setting on page 15.
b. Spark rod and UV
Make sure the spark rod is positioned above the pilot gas tube and that it will spark to
the end of the gas tube.
7. Main burner ignition
Close the manual gas valve.
a. Set the Modulating Gas Control System to low fi re position.
· Slowly open the manual gas valve.
· The fl ame should be evenly extending in the burner.
· The fl ame should be located in the casting of the burner.
· Check the fl ame signal.
Close the manual gas valve.
b. Set the Modulating Gas Control System to high fi re position.
· Slowly open the manual gas valve.
· Observe the fl ame at high fi re; the fl ame should be blue approximately 10
to 12 inches long. If the fl ame is long, lazy and orange the air to fuel ratio
is not correctly adjusted . The pressure across the burner should be
increased, refer to Chart 2.
· Check the fl ame signal.
· Check the manifold pressure to the corresponding fi ring rate. If the manifold
pressure does not correspond to the pressures shown in Chart 3. Re-adjust if
necessary.
For a high fi re start system the fi rst gas port next to the pilot might require to be blocked using
furnace cement to prevent potential pilot blow outs and fl ame failures. See Figure 7 - Pilot
Confi guration.
Slight redness and warpage of the baffl e plates may occur at the high and intermediate fi re inputs.
This will not harm the burner. Once an initial discoloration and warp has taken (“set”) no further
permanent change will take place.
If the end plates redness occurs during high and intermediate fi re inputs, the distance between the
end plates and the profi le opening might not be suffi cient for the air to cool the end plates. Profi le
readjustments might be necessary.
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Installation
Burner Setup Continued