Blower Temperature Switch Testing And Replacement - Bradford White TW 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 165°F?
N
Do switch contacts
open?
N
Switch OK
24
N
Replace switch
(see page 23)
N
Y
Do switch contacts
open?
Y Replace switch
(see page 23)
TTW SERVICE PROCEDURE V
Blower Temperature Switch Testing
120 volt potential exposure. Use caution
to avoid personal injury.
15
Exhaust
Y
temperature is too
hot.
and Replacement
WARNING
14
Blower temperature
switch location
Air mixing inlet
Common causes for
high exhaust temperature
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.
Page 24