Bradford White eF Series Troubleshooting Manual And Instructions For Service page 39

Blocked Vent Pressure Switch Testing and Replacement
WARNING
120 volt potential exposure. Use caution
making voltage checks to avoid personal injury.
Sequence of Operation: The blocked vent pressure switch monitors the pressure in the exhaust tube. The switch
contacts are normally closed and will not open unless there is a blockage in the exhaust venting or terminal (snow, ice,
debris). If the blocked vent pressure switch contacts open after the thermostat initiates the blower, the blower will remain
on for to 5 minutes waiting for the contacts to close. If the contacts remain open, the blower will stop and the PURGE
LED will flash for hot surface ignition models, or error code 29 will display for direct spark ignition models.
LED Status
Only power LED is on, or Purge LED flashing.
Error Code 29 or 26 (Integrated Control Models)
Error Code 67 (ICON System Control Models)
Does the blower
N
energize?
Y
Hot Surface Ignition Models:
Check Purge LED status. ICON
System & Integrated Control
Models: Check control display.
Y
On within 5 minutes?
N
Flashing after 5 minutes?
Error code 29 again?
Y
Check blower for proper
operation (see page 36)
Is blower O.K.?
Y
Refer to Check Collector Pressure (see next page).
Note: Hot
Surface Ignition
Models ONLY –
The blocked vent
pressure switch
must be used
with the revised
ignition control,
identified with a
yellow label.
Service Procedure VI
Replace vent
safety switch (see
Vent Safety
Switch
Replacement
Procedure, pg
47)
Pressure switch is O.K.
N
Call Technical
Support.
Correct blower problem
N
(see Blower Testing and
Replacement, pg 36).
Make sure exhaust collector compartment is not
overheating (350°F) before resetting vent safety switch. If
there is evidence the collector compartment is overheating,
call Technical Support.
Safety Circuit Trace
Is there
continuity
through gray
wire leads of
Y
heater side
safety circuit
harness? (see
image below).
N
N Depress reset
button on vent
safety switch.
Is there
continuity
across high
limit switch?
(see image
below).
Y
Does the heater function?
Y
Verify proper switch operation. (see Vent Safety
Switch Testing and Replacement, pg 47).
WARNING
Is there
continuity
Safety circuit
through red wire
leads of heater
N
side safety
Testing and
circuit harness?
Replacement,
(see image
below).
Y
Replace
Check Purge
pressure
LED status on
Y
switch (see
ignition module.
Is it flashing after
Pressure
45 seconds?
Replacement
Procedure, pg
Call
Technical
N
Support.
O.K. (see
Blower
pg 36).
exhaust
Exhaust
Switch
38)
39
39