OLD gas furnace blower issues

I have an old Honeywell gas burner furnace http://www.heatinghelp.com/files/articles/768/216.pdf that the blower won't shut off on. The furnace heats great, just won't shut off unless I shut the whole furnace down. Not a good thing when it's below 30 degrees, but have a gas fireplace been using to give the blower a break from time to time. This furnace has old mercury switches in it it's that old, and I'm desperate to not have to replace my furnace just yet. Please help!
--
MeredithCaudill

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Is it the furnace or just the blower that won't shut down?
If it is the furnace, either the problem is with the thermostat or a relay in the furnace controls is stuck on.
If it is the blower, either your thermostat has a blower switch that has been turned on or a switch inside the furnace has been changed to ON. Or possibly the fan limit switch inside the furnace controls is stuck in the on position. Really, it does no harm for the blower to be on all the time. I have kept my furnace fan running 24/7 for the past several years to improve the air circulation and prevent the air from stratifying.
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On 12/26/2012 12:15 PM, EXT wrote:

That's an old system and you have no idea if it was installed the way shown in the manual. I'd suspect that the fan runs as long as the firebox temperature is above some number. Suspect that thermal switch. And there may be another switch that shorts across that which may be in the wrong position or the wiring is shorted.
Really, it does no harm for the blower to be on all the

Depends on your definition of harm. Just doing the math, leaving my furnace blower on 24/7 would cost me $36/month in electricity. I call that HARM with a capital H.
I have kept my furnace fan running 24/7 for the past several years

The bottom line here is, even if you knew what was wrong, would you have the skills and the tools and the motivation to fix it yourself. And what would you do if you messed it up and the furnace quit working entirely? Or you messed it up differently and the burner stayed on until the house went up in smoke.
You really need somebody local, a friend, relative, neighbor to take a peek at it. And you really need to have faith in the person you have fix it. Don't trifle with stuff you don't understand that runs while you're not home and can burn the place down.
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Agree. On older furnaces like that there is typically a temp switch on the plenum. When the temp goes over a certain upper point, the blower turns on. When it goes below a lower limit, the blower turns off. That switch would be a prime suspect.
And there may be

Could also be the thermostat in the house has been set to "fan on". Or a bad thermostat, or short in the wiring.

I think the suggestion was made in the sense that it's not an immediate crisis that's going to ruin the blower or furnace.

Yes, I agree. You need to know your skills are appropriate for the job.
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On 12/26/2012 2:38 PM, snipped-for-privacy@optonline.net wrote:

I thought more about that. I consider myself a smart feller and have high confidence in my ability to do anything I set my mind to. But looking back over the last 65 years at all the bonehead actions and decisions I made with all that confidence... I'm amazed I'm still alive.
I just flashed on the image of me lying under my '55 ford with the transmission sitting on my chest and oil pouring in my face wondering, "what do I do now?" Good times...
Your skills have to actually BE appropriate for the job.
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I had my friends compact Chrystler (same size as a Lebaron) on a jackstand that was rated much higher than half his car, and while I was in the house, the jackstand collapsed a few inches. . I'm glad he wasn't under the car.

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You have a VOM? Feel like doing some trouble shooting?
Christopher A. Young Learn more about Jesus www.lds.org .
I have an old Honeywell gas burner furnace http://www.heatinghelp.com/files/articles/768/216.pdf that the blower won't shut off on. The furnace heats great, just won't shut off unless I shut the whole furnace down. Not a good thing when it's below 30 degrees, but have a gas fireplace been using to give the blower a break from time to time. This furnace has old mercury switches in it it's that old, and I'm desperate to not have to replace my furnace just yet. Please help!
--
MeredithCaudill



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Does it over heat the house? Or just blow althe time?
Christopher A. Young Learn more about Jesus www.lds.org .
I have an old Honeywell gas burner furnace http://www.heatinghelp.com/files/articles/768/216.pdf that the blower won't shut off on. The furnace heats great, just won't shut off unless I shut the whole furnace down. Not a good thing when it's below 30 degrees, but have a gas fireplace been using to give the blower a break from time to time. This furnace has old mercury switches in it it's that old, and I'm desperate to not have to replace my furnace just yet. Please help!
--
MeredithCaudill



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MeredithCaudill wrote:

Hi, I am retired ex-Honeyweller, never knew there was Honeywell brand furnace. Must be very OLD unit with LOW efficiency. Three things to check; malfunctioning thermostat, Stuck fan relay, High limit switch(relay), not necessarily in that order. Good luck fixing it.
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On 12/26/12 5:21 PM, Tony Hwang wrote:

FWIW, the original "print date" code on the manual's title page shows March of 1949 !!!
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.

a brand new furnace will pay for itself quickly.....
goodman furnaces cost far less than the major brands like lennox trane etc.
a few years ago my new forced air furnace with air cost 3500 bucks installed.
just a furnace around 1500 bucks
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Man, I don't know where you live that you get those kinds of prices. Those prices, $1500 for a furnace, $3500 for furnace plus AC, are more like the cost of the eqpt in my world. With install, typically 2X that.
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wrote:

THINK GOODMAN., the big companies selling trane etc charge twice the 3500 bucks
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I put in a Rheem 2 years ago, which isn't top of the line. I guess it's maybe one step above Goodman. $1500 for the furnace, $3500 for furnace plus AC were about the cost of the eqpt. And that is just the furnace, outside AC, and cased coil. Typically changing an ancient furnace like the OP has, you're going to be going to a condensing furnace, no? Especially if the goal is to get good efficiency. That means you now have PVC pipe/fittings to buy, maybe condensate pump. Then you have all the labor involved, paying for permits, etc. Getting rid of the old furnace. And you have other possible issues, like an orphaned hot water heater on a chimney that is now too large, so you may need a chimnely liner. I don't see how you get a furnace and AC installed for $3500 no matter whose eqpt you use, unless it fell off the back of a truck.
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wrote:

$1500 for a furnace and $3500 for furnace plus AC somebody is working for nothing, and will NOT be there for you when you need them for service down the line.
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On Wed, 26 Dec 2012 14:50:38 +0000, MeredithCaudill

Running the blower 24/7 won't hurt it. Will cost a bit in electricity use, but that's all. Does your thermostat have a fan switch on it by chance????
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Did we ever hear back from the OP?
Are we talking about blower on, or heat on all the time?
Christopher A. Young Learn more about Jesus www.lds.org .
I have an old Honeywell gas burner furnace http://www.heatinghelp.com/files/articles/768/216.pdf that the blower won't shut off on. The furnace heats great, just won't shut off unless I shut the whole furnace down. Not a good thing when it's below 30 degrees, but have a gas fireplace been using to give the blower a break from time to time. This furnace has old mercury switches in it it's that old, and I'm desperate to not have to replace my furnace just yet. Please help!
--
MeredithCaudill



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On Dec 27, 9:04pm, "Stormin Mormon"

No, they got blown away.

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Was animated thread, for awhile. Someone did a good job, throwing that meat to the wolves.
Ah, well, it was fun.
Christopher A. Young Learn more about Jesus www.lds.org .

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