Bradford White U-TW4-75S-76R-3N - Manual (Page 32)

Page 32
Blower Temperature Switch Testing (cont’d)
Switch Setting
Opens on rise @ approximately 165 o F
Auto resets on fall @ approximately 160 o F
Cool switch to
below 160 o F
Reconnect wire leads and ob-
serve heater operation. Do
exhaust gas temperatures
rise to or above 170 o F with
vent connected?
Replace switch
(see page 33).
Disconnect wire leads to
switch. Using multi-meter set
to the ohms setting. Is there
continuity between the switch
terminals?
Do switch
contacts
open?
Exhaust
temperature
is too hot.
Do switch con-
tacts open?
Replace switch
(see page 33).
Switch OK
Common causes for high
exhaust temperature
1. Vent length is below mini-
mum allowable
2. Vent diameter not to speci-
fication
3. Restricted dilution air inlet
4. Missing or deteriorated flue
baffle
5. Gas pressure is out of
specification
N
N
N
N
Y
Y
Y
Y
Blower Temperature Switch Testing
32