Reznor SC Duct Furnace Unit Installation Manual - Manual (Page 35)

Form I-SC, P/N 207696 R11, Page 35
10.2 Maintenance
Procedures
10.2.1 Gas Valve
WARNING
The operating valve is the prime safety shutoff. All gas supply lines
must be free of dirt or scale before connecting to the unit to ensure
positive closure. See Hazard Levels, page 2.
Remove external dirt accumulation and check wiring connections.
The combination gas valve must be checked annually to ensure that the valve is shut-
ting off gas flow completely.
Instructions:
1) Locate the 1/8” FPT INLET pressure tap on the combination valve (FIGURE 34).
2) With the manual valve turned off to prevent flow to the gas valve, connect a
manometer to the 1/8” inlet pressure tap in the valve. NOTE: A manometer (fluid-
filled gauge) with an inches water column scale is recommended.
Single-
Stage Valve
Two-Stage
Valve
1/8" INLET
Pressure Tap
1/8” Outlet
Pressure Tap
1/8" INLET
Pressure Tap
1/8” Outlet
Pressure
Tap
FIGURE 34 -
Top View of
Gas Valves
3) With the field-installed manual valve remaining closed, observe the manometer
for two to three minutes for an indication of gas pressure. No pressure should be
indicated on the manometer.
If the manometer indicates a gas pressure, the field-installed manual gas valve
must be replaced or repaired before the combination gas valve can be checked.
4) If the manometer does not indicate gas pressure, slowly open the field-installed
manual gas valve. After the manometer's indicated gas pressure has reached
equilibrium, close the manual shutoff valve. Observe the gas pressure. There
should be no loss of gas pressure on the manometer. If the manometer indicates
a loss of pressure, replace the combination gas valve before placing the heater in
operation.
NOTE: Operational pressure settings and instructions for checking pressure settings
are in Paragraph 6.2.
CAUTION: DO NOT
bottom out the gas
valve regulator
adjusting screw.
This can result
in unregulated
manifold pressure
causing excess
overfire and heat
exchanger failure.
10.2.3 Burner Rack
Removal Instructions
10.2.2 Vent/
Combustion Air
System
1. Turn off the gas supply.
2. Turn off the electric supply.
3. Remove control access side panel.
4. Disconnect the pilot tubing and flame sensor lead.
5. Mark and disconnect electric valve leads.
6. Uncouple the union in the gas supply.
7. Remove sheetmetal screws in the top corners of the burner rack assembly.
8. Pull "drawer-type" burner rack out of the furnace.
To disassemble the burner rack:
1. Remove Carryover System --
Natural Gas - remove the flash carryover system from the "manifold end" of the
burner rack
NOTE: Natural gas burner racks manufactured prior to Series 6 have a lighter tube
carryover system. Break the lighter tube connection at the orifice and remove the
supply tubing, the drip shield and the lighter tube.
Check at least once a year. Inspect all joints, seams, and terminal caps. Clean grills
and screens.
Replace any parts that need to be replaced.