Blower Temperature Switch Testing And Replacement - Bradford White M1TW40S Series Service Manual

Blower Temperature Switch
Testing.
Step 1. Position power switch on gas control
to the "OFF" position.
Step 2. Remove the three screws (Phillips screw 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 @ approximately 165°F
Auto resets on fall @ approximately 130°F
Cool switch to
below 130°F
Disconnect wire leads to
switch. Using a multi-meter
set to 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 170°F
with vent connected?
N
Do switch
contacts open?
N
Switch OK
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22
N
Replace switch
(see page 23)
N
Y Y
Do switch
contacts open?
Y Replace switch
(see page 23)
TTW SERVICE PROCEDURE V
Blower Temperature Switch Testing
and Replacement
WARNING
115 volt potential exposure. Use caution
to avoid personal injury.
15
Air mixing inlet
Exhaust 1. Vent length is below minimum allowable.
temperature is 2. Vent diameter not to specification.
too hot. 3. Restricted dilution air inlet.
4. Missing or deteriorated flue baffle.
5. Gas pressure is out of specification.
14
Blower temperature
switch location
Common causes for
high exhaust temperature
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