Furnace fix

slowhands · 2005-02-03T04:59:47+00:00

When my furnace wouldn't work, I called the local gas company (Excel Energy -- Minneapolis) figuring they would come out and look at it for free, like PG&E did in CA. But no, they wanted $80 for the first 15 minutes just to look at it, and I think it was $80 each half/hour after that, and so did all the private repair places I called. I fixed it myself and thought I would pass it on.The symptom was, when the thermostat went on, I could hear a fan run for a while, but no heat. Then this would repeat.My son Joe suggested I take the furnace panels off and look for a switch, and sure enough, there was a switch operated by vacuum from the stack, and the short vacuum hose was cracked and letting air in. But shorting out the switch didn't make the heat go on either, unless I let the fan run for a while first.I should mention that the front of the furnace contains a circuit board with ICs and a bunch of electronics on it, including diagnostic lights.To make it short, what happens is this, (at least on my Lennox.)1) When the thermostat goes on, the furnace computer requires that the vacuum switch be open (no vacuum). If so, then the stack fan is turns on.2) After the stack fan is on for a few seconds, the computer requires the vacuum switch be closed. This is to test the switch every time it goes on. (A faulty switch could be stuck in the closed position, then if the stack fan also failed, the system would work without it, causing possible CO problems.)So only if there is both no vacuum and then vacuum in sequence, the computer allows the gas to go on. All I had to do was replace the 1/4" vacuum hose and it worked fine. I spent $2 instead of $80+.

Furnace fix

Feb 03, 2005 22 Replies

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tnom 21 years ago

If you are talking about me what did I say that I did? Be specific

Why bother. It doesn't pay enough.

It's hard to answer a question when you haven't asked a question.

A bit defensive aren't you? You're not feeling guilty are you?

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steve 21 years ago

LOL.. OK. So you are a brain surgeon...or a lawyer right

For a guy what wants to make the world think that hes in the Forbes list, you dont read much do ya?

Oh..I did, like I said, you cant read well can you?

Not a bit there fella...anyone who knows me I have nothing to feel guilty for. Of course, when a real pro puts you to the test, its obvious how you reply...lol..

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tnom 21 years ago

Still waiting. Be specific.

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