Blower Temperature Switch Testing & Replacement - Bradford White UPV Series Service Manual

UPV Service Procedure VI – Blower Temperature Switch Testing and
Replacement
Blower Temperature Switch Testing
Step 1. Position power switch on gas control to
the "OFF" position.
Step 2. Remove the three screws (T20 Torx driver) from control access cover on blower and
remove cover (see photo 14).
Step 3. Locate blower temperature switch (see photo 15).
Switch Setting
Opens on rise at approximately 155°F.
Auto resets on fall at approximately 135°F.
Cool switch below 130°F.
Disconnect wire leads to switch. Using a
multi-meter set the ohms setting, is there
continuity between the switch terminals?
Y
Reconnect wire leads and observe heater
operation. Do exhaust gas temperatures
rise to or above 160°F with vent connected?
N
Do switch
contacts open?
N
Switch OK.
N
Y
Y
Replace switch
(see page 24).
14
115 volt potential exposure.
Use caution to avoid personal injury.
Replace switch
(see page 24).
N
Y
Do switch
contacts open?
Common causes for high exhaust temperatures
1. Vent length is below minimum allowable.
2. Vent diameter not to specification.
3. Restricted dilution air inlet.
4. Missing or deteriorated flue baffle
5. Gas pressure is out of specification.
Blower temperature
switch location
23
WARNING
Exhaust temperature
is too hot.
15
Air mixing
inlet
23