Oil furnace repair


10 year old Carrier oil furnace. It is vented through a power side vent through the side wall of the house (Tjurlund is the mfg of the venting system). When the tstat calls for heat, the vent comes on. the primary control never requests the burner to start. when I short out the T terminals on the primary control, everything fires off perfectly (I do annual nozzle and filter changes on all 4 oil appliances at my house). I do not understand the wiring from the tstat to the furnace adequately. I assume the tstat is working and assume that the problem is in the board. the tstat goes into a board and the output of the board goes into the oil primary control. dont know how to test to see if this is the case. I can take photos of everything and email to anyone who understands this situation. thanks
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snipped-for-privacy@erols.com wrote:

Forced air? hot water? Zone valves with 'valve open' contacts?
In some situations (all?) with a forced draft, there is a mechanism to make sure the draft is really there. On my gas hot water heater, it used an overheat sensor, your unit may have something that checks for the draft before allowing the unit to fire.
If you're into abuse, you can post this on alt.hvac, but there's a 90% chance you'll only receive abuse.
Dave
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" snipped-for-privacy@erols.com" wrote:

Probably a bad sensor in the power vent unit that confirms the draft is there before letting the burner run. Possibly a sail switch or a vacuum switch and sensing tube. Try to find a manual for the power vent unit online and it should show what it has for this safety sensor.
Pete C.
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On Wed, 29 Nov 2006 06:18:00 -0600, " snipped-for-privacy@erols.com"

I don't know much about this, especially for a furnace only 10 years old.

You know there is more to furnace cleaning than just that, right?
You may have to adjust the ignition electrodes, or at least verify that their spacing is correct; or clean a second filter in the pump, and you may well have to clean out the flue, and this fall, I definitely had to clean out the tubes between the fire chamber and the flue.
There were rocks in there, some almost as big as golf balls, made out of heating oil. They looked like steel slag, or lava with steam holes in the middle, but I could break them by squeezing. Still, they clogged my exhaust and made lots of smoke come out.
I also tried to vacuum inside the fire chamber, with a hose attached to my shop-vac with the soot proof filter bag, but I was not very successful. I don't how important this is.
Plus the tech would throw a smoke-stick in there as the last step, but I didn't have any smoke-sticks. I never got sure what they did.
Plus, there may be things that the tech did that I've forgotten to do.
Plus things he should have done but didn't. For example, only the first guy ever used gauges. Those who came for the next 21 years just looked at the flame and decided if they were happy or not. (Well, they always were happy, I guess, because they never did any adjustments.) I don't have gauges.
The first rebalanced the swinging damper using a guage, a later guy taped the whole thing closed, a later one untaped it when I asked about it being taped.

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