Bradford-White Corp Blower Temperature Switch Testing.

PDX SERVICE PROCEDURE V
Blower Temperature Switch Testing
and Replacement
Blower Temperature Switch
Testing.
WARNING
120 volt potential exposure. Use caution
to avoid personal injury.
19
Disconnect wire leads to
switch.Using a multi-meter
set to the ohmssetting, is
there continuity between
the switch terminals?
Switch OK
Cool switchto
below 130°F
N
Y
Switch Setting
Opens on rise @ app roximately 165°F
Auto resets on fal l @ approximately 1 30°F
Step 1. Position power switch on gas control
to the “OFF” posit ion.
Step 2. Remove tubing from inle t pressure tap.
Step 3. Remove the three scr ews (Phillips screw driver) from
control access coveron blower and remove cover (see
photo 19).
Step 4. Locate blower temperature switch (see photo 19)
Reconnectwire leads and
observe heater oper ation.
Do exhaust gas
temperatures rise t o or
above 165°F?
Replace switch
(see page 24)
Y
N
Do switch
contacts open?
Do switch
contacts open?
N
Y
Replace switch
(see page 23)
N
Y
Exhaust
temperature is
too hot.
Common causesfor
high exhaust temperature
1. Vent length is below minimu m allowable.
2. Vent diameter not to specifi cation.
3.Restricted dilution air inlet.
4. Missing or deter iorated flue baffle .
5. Gas pressure is o ut of specification.
Blower temperature
switch location
20
Air mixing inlet
Page 23
PDX Series
23