repair or replace furnace?

Old 11-13-08, 06:38 AM
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Question repair or replace furnace?

I have an 8 year old Janitrol furnace with a cracked heat exchange- costs about $700-$800 to replace heat exchange (just labor the part is under warranty) vs. around $2500 to purchase a new furnace (cheap one bottom of the line like ours is now).

We have been told that the rise is too high, thus overly stressing the furnace and contributing to it wearing out too soon (I understand it should not be broken this soon) and that this is happening because we don't have enough returns.

Apparenlty also in the summer we are getting water / condensation from the outside ac (heat pump???) that is running down into the basement onto the furnace and has rusted out the heat exchange.

What should I do? I plan on getting the AC problem fixed in the spring to get it ready for summer heat.

But what about the returns? Do I really need added returns or a smaller furnace?

Should I replace the furnace (an expense we really don't want to have right now) or just go ahead with repairing the heat exchange?

How much longer should I expect my entire furnace to last, being that it's 9 years old?
I don't want to repair the heat exchange if the probability of the whole thing going out is high, which I am guessing it is....

Advice is appreciated.

Old 11-13-08, 06:52 AM
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Repair or Replace

If the temperature rise is too great replacing the heat exchanger is a band aid. Either the furnace is too big for the house, the ductwork too small, or something is causing a restriction of the air going thru the furnace. The root cause needs to be taken care of regardless if you repair or replace. Obviously, if the furnace is too big & is replaced with a properly sized one, the cause is taken care of.

The estimate of $700-800 sounds high. Unless it is an unusually difficult installation, normally it only takes a couple of hours to replace a heat exchanger. I suggest you shop around if you have the time.
Old 11-13-08, 08:06 AM
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Is this Janitrol of this vintage a cheap unit? My furnace runs climbing to 180 degres during it's cycle, and that is out the register!, for at least 24 year age of furnace. And mirror inspection shows no problem + I'm at 0 on CO detector.

Could someone with a problem like the poster compromise in expense if problem is not economically solveable, to lower limit temp on furnace some?

And if high heat rise is his (or anyone elses problem, with a similar problem), then why isn't the current high-limit setting preventing the problem? Or is this furnace so underdesigned that it can't even handle temps anywhere near the limit temp?

Or are there some other design issues in play, where the heat exchanger cools too rapidly after the cycle, or say from cold flue back drafts?, actually causing the crack?, rather than temp rise?

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