Greenheck DGX Installation, Operation And Maintenance Manual page 24

Step 5 Set the Maximum Firing Rate
(...continued)
While monitoring the units temperature rise, set the
maximum firing rate by adjusting the regulator (shown
in figure #46) until the designed temperature rise is
achieved. After setting the maximum firing rate,
reconnect the wire to the amplifier.
IMPORTANT!
Setting the maximum firing rate during mild
weather conditions may cause the high limit to
trip out during extreme conditions requiring
manual resetting.
Clockwise rotation increases the temperature rise, counterclockwise rotation decreases the
The minimum setting for the maximum firing rate may be higher than required. This is acceptable, the
Step 6 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 shown in figure #47.
After setting the minimum firing rate, reconnect the wire to the modulating valve.
IMPORTANT!
The proper minimum firing rate setting results in
a small ribbon of continuous flame which covers
the flame rod and runs 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.
NOTE!
Adjusting the maximum and minimum fire may
require the inlet air sensor to be initially set
higher than desired in order to start the
burner(s). Once high and low fire have been set,
the inlet air sensor should be turned down to the
desired temperature.
NOTE!
Counterclockwise rotation increases the
minimum fire rate setting, clockwise rotation
decreases the setting.
Start-Up - Direct Gas
NOTE!
temperature rise.
NOTE!
burner will modulate as needed.
The minimum firing rate setting is critical. If the
low and the flame rod may not detect the flame.
24
Figure 46. Regulator
IMPORTANT!
settings is too high, the unit may not light, too
Remove one wire to
send the unit to the
minimum firing rate.
Minimum
firing rate
adjustment
Figure 47. Modulating Valve
Maximum
firing rate
adjustment