c. Check the ignition spark operation. Time must be within the lockout timing period (15 or 90 sec- onds).
d. Turn control down to end call for heat and wait 60 seconds on lockout models before beginning step 3.
3.Turn on gas supply.
4.Set controller to call for heat.
5.System should start as follows:
a.Spark will turn on and pilot gas valve will open and the blower will begin running.
b.Heater will operate until call for heat is satisfied.
burner Adjustment
This burner assembly does not require any primary air adjustments.
COMBUSTION
AIR BLOWER
AIR SHUTTER
ADJUSTMENT
GAS
VALVE
BURNER
BURNER
HOLD-
DOWN
BRACKET
Fig. 35: Low NOx Burner Tray Assembly
Visual Inspection
Flame can be observed through the slot opening above the plenum. Flame color is blue and evenly spread on the top surface of the burner. A visual inspection should be made monthly of the burners. In case flame lifting is observed on the burner, check gas pressure on manifold and static pressure in plenum. Gas pressure in manifold should be 3.9" WC and stat- ic pressure in plenum should be greater than 0.5" WC.
Electrical
Be sure that electrical service to the heater has prop- er overload fuse or circuit breaker protection, and wire size and connections comply with all applicable codes.
High Gas Pressure Switch
Pressure switch senses high pressure and automati- cally shuts down burner if abnormal pressure exists.
burner Tray Removal
1.
2.
3.Remove front door.
4.Disconnect gas line from gas valve.
5.Remove (2) screws that mount burner tray to unit, and (4) screws that secure gas valve to jacket.
6.Disconnect wires that terminate at gas valve.
7.Unscrew (4) screws that secure the control box.
8.Disconnect pilot wire from the ignition module.
9.Disconnect wire harness from the combustion blower.
10.Carefully slide out the burner tray assembly.
11.Reverse above procedure to reinstall.
Gas Valve Removal
1.
2.
3.Remove front door.
4.Disconnect gas line from gas valve.
5.Disconnect wires, pilot tubing and bleed line, if required.
6.Remove (2) screws that secure gas valve to jack- et.
7.Turn vertical gas pipe from manifold slightly and unscrew gas valve.
8.Reverse above procedure to
Fig. 34: Gas Pressure Switch
34