furnace blowing all the heat up the chimney

Of course, that's totally possible. Bad fan limit switch.
I've seen that before.

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Christopher A. Young
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"Van Chocstraw" <[Only registered and activated users can see links. ]> wrote in
message
news:[Only registered and activated users can see links. ]...

Your stack controls are out of adjustment. The blower should
cut off at
80. It should cut on at 100.

Stormin Mormon wrote:

Isn't that what "One would presume those are .. input/output ratings"
says???

I gave an alternate outside chance possibility but clearly stated it as
such...

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[Only registered and activated users can see links. ] wrote:

Well, certainly isn't here and it gets pretty cold as well...0F and
below pretty common...

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<[Only registered and activated users can see links. ].ca> wrote


Yup. Deliberate too. It's to protect the pipes from freezing.

cshenk wrote:

Well, here it isn't--they'll duct it normally w/ vents in used space.
Seems a terrible waste otherwise to heat w/o any control all that volume.

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dpb wrote:
....


Anything built in the last 20 years or so anyway, that is. Back in the
60s and earlier one saw lots of things done that make no sense
whatsoever under today's operating costs. That sorta' changed in the
70s and by 80s pretty much gone around here.

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I reply to messages as I scroll through. I do not read all
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Christopher A. Young
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"dpb" <none@non.net> wrote in message
news:hct3ol$cde$1@news.eternal-september.org...
Stormin Mormon wrote:

Isn't that what "One would presume those are .. input/output
ratings"
says???

I gave an alternate outside chance possibility but clearly
stated it as
such...

--

[Only registered and activated users can see links. ] wrote:
Hi,
To me the furnace is a bit undersized to begin with.
First thing first,
If blower motor has a speed tap, it should run slower than when in
cooling mode.(warm air is light vs. cold air) Does cooling mode work OK
in summer? Had a look at evaporator coil? Is it clean?

<[Only registered and activated users can see links. ].com> wrote in message


My first thought is that the unit is a bit on the small size for that house
but I don't know the construction. That said, if it has been there for 10
years it must have done the job at some point. You should be getting more
than 70 degree air While the stack will be hot, it may be much more than
needed. Sounds like there could be a problem with the heat exchanger if
heated air is getting by. I think what you really need as a more competent
service tech. They should be taking the temperature of both the stack and
the plenum.

On Wed, 4 Nov 2009 18:11:57 -0500, "Colbyt"
<[Only registered and activated users can see links. ]> wrote:



That furnace is NOT undersized if the house is reasonably well
insulated. The only reason the furnace in my house is as big as it is,
is I could not buy one smaller. Perfect size would have the furnace
running full time on the coldest day to maintain temperature. My
furnace has NEVER run over 8 hours in a day. - which means at 50,000
BTU it is TOO BIG. You loose a LOT of efficiency if the unit is too
big.