Form I-UDA, P/N 195673 Rev 13, Page 34
10..7 Operating Gas
Valve
10..8 Combustion Air
Pressure Switch
See
FIGURE 18
, page 30, for location. (NOTE: Depending on date of manufac
-
ture and size, pressure switch may not be in the location indicated. Check the
control bracket on the bottom of the compartment or further down on the com
-
partment wall.) If it is determined that the pressure switch needs replacing, use
only the factory-authorized replacement part that is designed for the model and
size of heater being serviced.
NOTE
: A unit operating above 6000 ft (1830M) elevation requires a high altitude
pressure switch. See Paragraph 3.2.
10..9 Limit Control
If it is determined that the limit control needs replacing, use only a factory-
authorized replacement part that is designed for the size of heater.
For approximate limit location, see
FIGURE 18
, page 30.
WARNING: The op-
erating valve is the
prime safety shutoff.
All gas supply lines
must be free of dirt
or scale before con-
necting to the unit
to ensure positive
closure. See Hazard
Levels, page .
Carefully 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” NPT pressure tap on the combination valve.
Single-Stage
Valve
1/8” Outlet
Pressure Tap
1/8” Outlet
Pressure Tap
Two -Stage Valve
NOTE:
Operational pres-
sure settings and instruc
-
tions for checking pressure
settings are in Paragraph
6.1.
FIGURE 4 - Pressure Tap for Checking Gas Flow Shutoff
2) With the manual valve turned off to prevent flow to the gas valve, connect a
manometer to the 1/8” outlet pressure tap in the valve. NOTE: A manometer (fluid-
filled gauge) is recommended.
3) Turn the manual valve to the ON position and the heater OFF. Use your finger to
fully block the main burner orifice for several seconds. Observe the manometer
with the orifice blocked, and if any pressure is indicated, the gas valve is leak
-
ing.
A leaking gas valve must be replaced before the heater is put back in
operation.
3. Disconnect the three venter motor wires at the DSI control, capacitor wires at the
capacitor (if applicable), and ground screw (located on the control panel).
4. Sizes 30 and 45 - Disconnect the gas train and move it out of the way. Disconnect
the gas supply at the union outside of the cabinet. At the gas valve, mark and dis
-
connect the wires. Carefully remove the burner orifice and orifice adapter locking
nut. Slide the orifice adapter out through the bracket on the burner pushing the gas
train to the right. This will move the gas train out of the way.
5. Holding the venter motor, remove the three or four screws that attach the venter
motor mounting plate to the venter housing. Remove the motor and wheel assem
-
bly from the heater.
6. Re-assemble with the replacement venter motor and wheel assembly. See
FIG-
URE 3
.
7. Follow the wiring diagram to connect the venter wires.
8. Sizes 30 and 45 - Reconnect the gas supply at the union outside of the cabinet.
Leak test the connection with leak detecting solution.
9. Replace the access panel. Restore power to the heater and turn on the gas.
Light, following the instructions on the lighting instruction plate. Check for proper
operation.
10. Maintenance
and Service
(cont’d)
10. Maintenance
Procedures
(cont’d)
