Heat Overload turns on Furnace Blower

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We have been having a heat wave, with temps up near 100 degrees for well over a week. Today it got so hot in my house that the furnace blower kicked on. I thought that was rather odd, since I do not have central AC. Then it hit me. It was so friggin hot that the furnace sensor (probably a klixon) thought the burner was on, and the blower kicked in. I shut off the power to the furnace, but that tells me it's time to set up my tent, since it's just too frikkin hot to stay in the house, especially since Sunday is supposed to hit some sort of heat record.
Mark
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Good to hear it's happened to you too. I've been watching a friends house while he's away.
The thermostat has <HEAT> <OFF> <COOL> setttings, and it was set to <OFF>
THe inside of the house was close to 100 degrees, and the furnace blower motor was running.
The only way I could get it to stop was to flip the circuit breaker !
I was getting ready to call a HVAC guy until I read your post.
On Fri, 15 Jul 2005 23:51:04 -0500, snipped-for-privacy@UNLISTED.com wrote:

<rj>
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wrote:

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If that furnace is in the attic it is possible for the temperature to get high enough occasionally for a bi-metal fan switch to to close even if it is properly adjusted. I have also seen it happen on mobile homes with the fixed disc fan switches. Solution-- run the A/C. Larry
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snipped-for-privacy@carolinabreezehvac.com wrote:

Well its not just the overheat setting
My furnace blower continues to run after the fire shuts off as the heat exchanger cools down and it continues to run untill the air is at about 100 F. Due to hystereisis it takes a higher temp to get it to turn on, but onece on, it won't turn off untill the air drops below 100F.
His blower control may be a bit out of adjustment but not anything serious.
Mark
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No one said it was.

Belive thats what we said..

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In alt.home.repair on 17 Jul 2005 07:35:36 -0700 "Mark"

Is this really hysteresis or just a thermostat that is designed to turn off at a lower temperature than it turns on at?

Meirman -- If emailing, please let me know whether or not you are posting the same letter. Change domain to erols.com, if necessary.
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n. pl. hystereses [ -sz ]
The lagging of an effect behind its cause, as when the change in magnetism of a body lags behind changes in the magnetic field.
Not *hysteresis* according to Webster. But language is an evolving art and Webster is sometimes slow in catching up with technical jargon. I have used and heard *hysteresis* used in the same sense as by the previous poster and it has always been understood.
SJF
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
On Sat, 16 Jul 2005 08:06:30 -0400, " snipped-for-privacy@carolinabreezehvac.com"

Guess what? In our school bungalos (sans a/c), the unit's fan controls would kick in at 110. And it got hot enough in the summer, in the LA suburbs...
....nothing to do with the high limit
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--
-john
wide-open at throttle dot info
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Just leave it on. Won't hurt anything.
--

Christopher A. Young
Learn more about Jesus
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Stormin Mormon wrote:

<snip>
Right. It is a great way to help keep the house cool. The fan is on a fractional horse motor, costs pennies to run and will keep the A/C from kicking on for another hour or two.
I posted that this morning (and two others) but haven't seen any of them.
Harry K
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Harry K wrote:

My version of physics seems to conflict with that notion.
hvacrmedic

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RP wrote:

Try it and see. It works by having the air in the room moving. You feel more comfortable at the same temperature and can set the A/C higher. Mine goes on about noon every day in summer and stays on until bedtime. If you have a basement and have a way of sucking your feed air from there, you gain even more.
Harry K
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a
from
And its against all known building codes for a reason.

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message

This is Turtle.
WOW Your fixing to tell me something here why drawing air from a basement is against every building code there is. what if the draw air supply / furnacers are in the basement ?
TURTLE
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on
is
furnacers
Do you have a copy of the IBC? If you do, read it retard. You cant just arbitraly start drawing air from a basement.

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Steve, I habe a copy of the international building code and the International residential mechanical code. I could not find where it said you cannot have a return in the basement, unless the basement was so small that it would remove the combustion air from the room and backdraft the flue. Perhaps you could quote chapter and verse?
However, it still would not cool the house in that situation, unless you have a VERY COLD basement.
Stretch
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Stretch wrote:
<snip>

How so? My basement is cool enough that there is a noticeable drop in temp as I go down there. The air is very definitely much cooler than the living area and for sure cooler than the A/C cut-in temp. It is not VERY COLD tho. Any air cooler than the cut-in temp is an aid. Granted that air doesn't last all that long.
Harry K
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This is Turtle.
awwww , Don't worry about it for Steve was tring to Dazzle a Turtle from the Backwood with some big fancy 50 cent words and book referrances. He was just bullshit everybody.
TURTLE
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message

This is Turtle.
That is not a answer at all. If that was true. You could get the same answer from having a dictionary also.
TURTLE
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