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I ran into an electric furnace today that will not shut off. It is central forced air, and it would not shut off if the temperature was met, so I switched the system off, and it wouldnt stop blowing hot. Finally had to shut it down at the panel, but was wondering if anyone had an idea as to the cause.
Thanks for any help,
Drew McGee
Its been awhile, but possibly the sequenser (which sequenses the heat strips) or a contactor??
I would be betting on a bad thermostat.Quote:
Originally Posted by Drew McGee
Was the system running before you broke it? :D
I hope you told the homeowner that you shut down the system.....
Drew,Quote:
Originally Posted by Drew McGee
How long did the blower run after the temp was met / switched off ?
The system was on, but I lowered the temp. I prefer the term 'failed under test', but the seller is aware of the situation.
The system ran for around 30 minutes, but it was more than the blower, the strips were hot the entire time, even after it was off at the thermostat.
Sequencer failure, very common failure on electric furnaces.
A thermostat failure is not likely if you used the system switch (Heat, Off, Cool) after turning the temperature back to normal.
Thanks for all your answers
Scott, you crack me up.Quote:
Originally Posted by Scott Patterson
Is the fan switch set to "run" or "AUTO'?
Jim,Quote:
Originally Posted by Jim Zborowski
That was my thought too, and (I suspect) that of Billy when Billy asked "How long did the blower run after the temp was met / switched off ?".
Drew said "The system ran for around 30 minutes, but it was more than the blower, the strips were hot the entire time, even after it was off at the thermostat."
That would not be the fan set to 'On' instead of 'Auto'.
Like Scott said, you broke it man. :)Quote:
Originally Posted by Drew McGee
You really need to stop running into things like that. :D
Quote:
Originally Posted by Jerry Peck
I was thinking cool down period, my money is on the Limit Switch. :)
The limit switch is a safety that never comes into play unless the furnace is on a runaway. The blower and heat strips continuing to run could be stopped by the limit switch if there was too much heat, but that would only occur if the normal operating control is broken.
Sequencer switch is the culprit.
OK, I missed that. Thought he said the blower wouldn't stop.
Either way time for The Trades. :)Quote:
Originally Posted by Jim Luttrall
Agreed.Quote:
Either way time for The Trades. :)
Thanks again. By The Trades, are you saying its time to call in a service tch?
Yes, "Trades" would mean someone specifically trained in one of the specialties such as A/C, Electric, Plumbing.
Thanks. That was my initial call,I was just trying to get a handle on the cause.
If the limit had tripped (over heat condition) and the heat strips were still running, that sounds like a melt down. Better call the HVAC guy.Quote:
Originally Posted by Billy Stephens
[quote=Drew McGee;31082]I ran into an electric furnace today that will not shut off. ]
Did you have the right thermostat? :D