Bradford White UPDX2-75T6FRN - Manual (Page 23)

UPDX SERVICE PROCEDURE V
Blower Temperature Switch Testing
and Replacement
Blower Temperature Switch
Testing
WARNING
115 volt potential exposure. Use caution
to avoid personal injury.
Disconnect wire leads to
switch. Using a multi-meter
set to the ohms setting, is
there continuity between the
switch terminals?
Switch OK
Cool switch to
below 125°F.
N
Y
Switch Setting
Opens on rise @ approximately 155°F
Auto resets on fall @ approximately 128°F
Step 1. Position gas control power switch
to the “OFF” position.
Step 2. Remove the three screws
(Phillips screw driver) from
control access cover on
blower and remove cover
(see photos 18 and 19).
Step 3. Locate blower temperature
switch (see photo 20).
Reconnect wire leads and
observe heater operation. Do
exhaust gas temperatures rise
to or above 175°F?
Replace switch
(see page 24).
Y
N
Do switch contacts
open?
Do switch contacts
open?
N
Y
Replace switch
(see page 24).
N
Y
Exhaust
temperature is too
hot.
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.
6. Excessively high ambient temperatures.
Blower Temperature
Switch Location
20
Air Mixing Inlet
Page 23
UPDX Series
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.
6. Excessively high ambient temperatures.
Gas Control shown in the “OFF”
Position
18
Control Access
Cover Screws
19
23