On 21 Mar 2007 22:23:35 -0700, "scidoc" wrote:

On Mar 21, 8:30 pm, "Toller" wrote:
"Ken" wrote in message

...

scidoc wrote:
As I am getting a little older, I'm getting lazy. Called Heating
Repair to assess no heat
from a BDP furnace. When told gas valve was defective, wife implored
let him fix it.

This all worries me too. I get a lot more upset when someone I hire
messes up than when I mess up myself. And I'm getting lazy too.

This was after $89 diagnosis fee not applied to $450 for valve. EF
32CW 183 replaced
unit not working; now told igniter defective, then printed circuit
board defective. As I am
an elec engineer, I informed tech that multiple problems were not
likely. Checked old solenoid
coils have appropriate impedance.

After throwing tech out, got off my ass and inspected furnace.
Solenoid is clicking but no ignition. Checked wiring and by placing
a little pressure on connector to printed circuit board furnace
ignited and functioned normally for about ten days.

Then stopped working.
Inspected again and cleaned connections with switch cleaner.
Now, pilot ignites, small fan does not turn (I think this flue fan
did before) and after 5 seconds or so instead of gas valve fully
opening
goes back to clicking solenoid. I think either the flue is not
present
due to the fan not turning or less likely, the bimetal is not reacting
to the pilot flame.

I am an experienced hands on engineer who can fix anything, given
adequate
schematics. I understand safety. Can anyone explain the appropriate
start
sequence with voltages at appropriate locations? I have a pretty good
general idea,
and have worked on old furnaces before (my own). Thanks in advance
for any help.

When the thermostat calls for heat, I believe the first thing in the cycle
is the starting of the flu blower/fan. A pressure switch detects it
having turned on, and then the ignitor is activated followed by the gas.
There are sensors for the gas having been lighted, but you are on the
right track from my understanding of the sequence.

Sounds like the guy you hired knew less than you do. Anyone can keep
replacing parts and eventually find a problem.

My father was a radio technician in WWII. He was taught to replace parts
until the radio worked. And he was as close to "anyone" as you can get.

THANKS FOR THE REPLY. THE MOTOR IMPEDANCE IS NORMAL.
SO NOW NEED TO CHECK THE RELAY (SOLENOID) VOLTAGE
AND DETERMINE IF IT IS SWITCHING.

QUESTION: 1. DOES THE INDUCER RUN CONSTANTLY THE ENTIRE TIME
THE FURNACE IS ON? I THINK YES.

2. THE VOLTAGE LOOKS LIKE 110 ON THE SCHEMATIC. I AM THINKING OF

I have no idea if it is 110 or not, but if there is no transformer to
lower the 110, probably is. If there is a transformer, you can
probably find two points near the relay to measure if it 110. If you
can't merely replacing the relay likely won't work.

SUPPLYING 110 TO THE FAN DIRECTLY WITH JUMPERS BYPASSING THE RELAY
TO TEST THE MOTOR WITH VOLTAGE. IF IT WORKS THE THE RELAY IS BAD.

3. SINCE THE RELAY IS SEALED ON A PRINTED CIRCUIT BOARD, CAN IT BE
REPLACED
WITHOUT REPLACING THE BOARD? ANY 110 V RELAY SHOULD WORK???

Not counting the obvious, single pole/double pole/etc, not big enough,
yes.

Again, I haven't seen what heater boards are like in the last 20
years, if they are still single layer or multiple layer. Mulitple
layer could be very hard, but on single layer, if your relay won't fit
in the space, you can run wires from all the pin mounting points and
put the actual relay anywhere you want.