Start-Up Direct Gas
important
For proper unit function and safety, follow the
important
This
1. Check the Supply Gas Pressure
Check the supply gas pressure and compare it with the unit’s nameplate pressure requirements. Adjust the supply regulator as needed until the supply gas pressure is within the specified range.
Minimum and maximum gas pressures for maximum output
Start-Up Direct Gas
• 100% Outside Air
important
Proper air velocity over the burner is critical on direct fired gas units. If the air velocity is not within the unit specifications, the unit will not operate efficiently, may have sporadic shutdowns and may produce excessive carbon monoxide (CO) or other gases.
4a. Set the Burner Air Pressure Differential
With the fan running and discharging 70°F (21°C) air, connect a
Outer Sensing Probes
9
MAX BTU/HR
BTU/H MAX
NORMAL MANIFOLD
PRESSURE“ W.C.
PRESSION DÕADMISSION NORMALE
MIN GAS
PRESSURE“ W.C.
PRESSION DE GAZ
MIN BURNER
PRESSURE DROP“ W.C. PERTE MIN DE PRESSION
DANS LE BRULEUR
TYPE OF GAS
NATURE DU GAZ
EQUIPPED FOR | AGAINST |
| SCFM |
MIN BTU/HR
BTU/H MIN
MIN GAS PRESSURE
FOR MAX OUTPUT“ W.C. PRESSION DE GAZ MIN
POUR PUISSANCE MAX
MAX GAS
PRESSURE“ W.C.
PRESSION DE GAZ MAX
MAX BURNER
PRESSURE DROPPSI PERTE MAX DE PRESSION
DANS LE BRULEUR
DESIGN ∆T | F | |
∆T NORMALE | ||
| ||
|
| |
| EXTERNAL STATIC PRESSURE | |
“ W.C. |
|
8 
7 
0.625 - 0.675 in. WC
6 
Measuring the Pressure Drop
Adjustable 
Top Baffle
CONCU POUR | CONTE |
PRESSION STATIQUE EXTERIEURE |
Airflow
The proper static pressure should be between 0.625
Type of gas
Direct Gas Nameplate
2. Check the Pilot Gas Pressure
Check the pilot gas pressure. The recommended gas pressure is 3 inches wc. Adjust the pilot regulator as needed. See the Gas Train Layout in the Reference section for the location of the pilot pressure test port and pilot regulator.
Burner
Adjustable 
Bottom Baffle
and 0.675 inches wc. If needed, evenly adjust the baffles above and below the burner, keeping the burner centered in the opening until the required pressure is obtained.
3.Check the Optional High and Low Gas Pressure Switches
Check the settings on the high and low gas pressure switches. The high pressure setting is typically 8 inches wc and the low pressure is setting is typically 3 inches wc. The switches are set at the factory and should not need adjustment. Adjust the setting if needed. See the Gas Train Layout diagram in the Reference section for the high and low pressure switch location.
note
The purpose of the high and low gas pressure switches is to automatically shutdown the burner if the inlet gas pressure is too low for the burner to safely light, or if the manifold pressure is too high for the burner to operate safely.
®
Burner and Baffles
Note
When required pressure is obtained, be sure to reconnect the outer sensing probes.
important
This process may need to be repeated until the proper pressure is achieved. This adjustment will change the air quantity delivered by the unit and therefore the air quantity delivered should be rechecked. Refer to the Blower
Note
To increase the static pressure decrease the opening. To decrease the static pressure increase the opening.
DGX Industrial Space Heating 11