Greenheck DG / DGX Industrial Space Heating (464044 IOM) (Pre-2009) - Manual (Page 15)

Start-Up - Direct Gas
Step 7 Set the Minimum Firing Rate
Disconnect and isolate one of the wires running to the
modulating valve to send the unit to its minimum
firing rate. Set the minimum firing rate by adjusting
the needle valve as shown in the figures #23 and #24.
After setting the minimum firing rate, shut off the pilot
to ensure that the flame safeguard can still read the
main flame signal. Reconnect the wire to the
modulating valve and open the pilot shut-off valve.
Remove and isolate one
wire to send the unit to
the minimum firing rate.
Minimum
firing rate
adjustment
Remove and isolate
one wire to send the
unit to the minimum
firing rate.
NOTE!
Gas trains are equipped with either separate regulators and modulating valves or with a combined
modulating regulator.
NOTE!
On units with a 42 inch or greater burner, the flame safe guard will automatically shut off the pilot
10 seconds after the burner has been ignited.
IMPORTANT!
The proper setting for the minimum firing rate
results in a small ribbon of continuous flame
across the entire burner.
IMPORTANT!
Do not allow the disconnected wire to come in
contact with a potential ground. Damage to the
amplifier or transformer could result.
S - 7
NOTE!
Adjusting the maximum and minimum fire requires the inlet air sensor to be set higher than the
outdoor air temperature in order to start the burner. Once high and low fire have been set, the inlet
air sensor should be set to the desired temperature.
NOTE!
Counterclockwise rotation increases the
minimum fire rate setting, clockwise rotation
decreases the setting.
Separate Regulator and
Modulating Valve Combined Modulating
Regulator
Minimum firing rate
adjustment
Figure 23. Separate Regulator and Modulating Valve
Figure 24. Combined Modulating Regulator