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ULTRA HIGH EFFICIENCY POWER VENT/POWER DIRECT VENT - SERVICE MANUAL
Technical Literature Department 18 of 52 Ashland City, TN © 2008
Servicing should only be performed by a Qualified Service Agent
AIR PRESSURE SWITCHES
Air pressure switch technical bulletins TB-A023-06 and TB-S023-06 explain air pressure
switch construction and test procedures in detail. These technical bulletins are available on
the manufacturers web site or by calling the technical support phone number shown on the
water heater labeling. Construction and types of air pressure switches used on the water
heater covered in this Service Manual are shown below.
Vent Port
Sensing PortFlexible Diaphragm
Wiring TerminalsSwitch Contacts
Normal State
(open switch contacts)
Activated State
(closed switch contacts)
Internal Linkage
Normal State Activated State
Blower Prover
Air Pressure Switch
Normally open contacts,
close on a rise in pressure.
Blocked Exhaust
Air Pressure Switch
Normally closed contacts,
open on a rise in pressure.
Blocked Intake
Air Pressure Switch
Normally closed contacts,
open on a fall in pressure.
Construction
Application & Type