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Reznor UDBS Unit Installation Manual User Manual

Page 39

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Form I-UDB, P/N 202658 R14, Page 39

10.2.8 Combustion Air

Pressure Switch

See

FIGURE 22, page 35, for location. (NOTE: Depending on date of manufacture 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 compartment 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 pres-

sure switch. See Paragraph 3.2.

10.2.9 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 22, page 35.

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.

NOTE: Operational

pressure settings and

instructions for checking

pressure settings are in

Paragraph 6.1.

FIGURE 27 - 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 leaking.

A leaking gas valve must be replaced before the heater is put back in

operation.

10.2.10. Door Switch

- UDBS only

If it is determined that the door switch needs replacing, use only a factory-

authorized replacement part that is designed for the heater.

For approximate switch location, see

FIGURE 22, page 35.

10.2.11 Transformer

See

FIGURE 22, page 35, for location. Use a voltmeter to verify that

there are 24 volts output from the transformer. If the transformer is not

functioning, it must be replaced. Use a replacement transformer identi-

cal to the factory-installed model.

10.2.13 Vent or Vent/

Combustion Air

System

The disconnect switch is located in the sealed electrical box inside the control

compartment with the toggle on the rear of the heater.

If it is determined that the disconnect switch needs replacing, use only the fac-

tory-authorized replacement part that is designed for the heater. Always replace

electrical box cover.

10.2.12 Disconnect

Switch - UDBS only

Check the complete system at least once a year. Inspection should include all joints,

seams, concentric adapter box (UDBS), inlet air guard or inlet air cap (UDBS), and the

vent terminal cap. Clean openings. Replace any defective parts.

Single-Stage Valves

1/8” Outlet

Pressure Tap

1/8” Outlet

Pressure Tap

Two -Stage Valve

1/8” Outlet

Pressure Tap

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