Direct Gas Make-Up Air
30
4. Set the minimum firing rate
Set the minimum firing rate to achieve a small ribbon of
continuous blue flame across the burner.
Disconnect one of the wires going to the modulating
valve and isolate. Set the minimum firing rate by
adjusting the minimum firing rate adjustment on the
modulating valve. Cycle the heat to make sure the
burner can light at this low fire setting.
5. Resume normal operation
Reconnect wires to Maxitrol amplifier and modulating
valve removed in previous steps.
6. Perform final flame signal check
Measure DC voltage at flame signal test ports (+/-) on
burner controller. Signal must be above 1.25 VDC and
steady. If flame signal is insufficient, repeat steps #1-4.
1. Energize the heating
Connect terminals R to W1.
2. Set pilot gas pressure
Close main hand valve, then set the pilot gas pressure
to 1.5 - 3 in. wg. Measure DC voltage at flame signal
test ports (+/-) on burner controller. Signal must be
above 1.25 VDC and steady. Adjust pilot gas pressure
up or down, if necessary, to achieve acceptable flame
signal. In some cases, reducing pilot gas pressure can
increase flame signal.
3. Set maximum fire rating
Open main hand valve and then set maximum firing
rate to the design temperature rise found on the direct
gas nameplate located on the outside of the unit on the
control center side.
Send unit to high fire by removing the wire connected
to terminal 3 of Maxitrol 14 or 44 Series amplifier. If
equipped with the Maxitrol SC Series amplifier, remove
the wires from terminals T1 and T2 and connect
terminals T1 and T2 with a field-supplied jumper wire.
While measuring temperature rise,
temperature rise =
discharge temperature - inlet temperature,
adjust the
maximum firing rate to achieve desired temperature
rise.
Start-Up: Direct Gas-Fired Heating
120V Industrial Pilot System (12-inch burner or greater)
DC Voltmeter and Flame Amplifier
Combined Modulating Regulator
Maximum firing
rate adjustment
Remove one
wire to send
the unit to
the minimum
firing rate
Minimum firing
rate adjustment
DC Voltmeter and Flame Amplifier
Remove cap to access
maximum firing rate
adjustment
Remove one wire to
send the unit to the
minimum firing rate
Separate Regulator and Modulating Valves
Minimum
firing rate
adjustment
