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bad thermostat?

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dogboy

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old honeywell- mercury switch

 

blue lever for low setpoint, red lever for high set point

 

old enough not to owe me a thing

 

the heat seems to come on now only by raising the low temp-

 

red lever does not seem to do a thing anymore- this in the last day or so

 

prolly time for a new one

 

oil-fired hot air

 

old one had a battery operated clock and a mechanical timer set up that we never used

 

i know the programable digital models are cheap enough and can be set for weekend times and temps, but the ones i've seen are not exactly intuitive

 

we aren't so senile that we forget to turn the heat down when we leave the house (yet)

 

any recommendations for the replacement?

 

any installation hints?

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Have one that is very similiar that is made by Sears.....

 

I am assuming the heat doesn't fire up even if you raise the High setpoint lever?

 

On mine at least, there are TWO mercury bulbs in there, one for each lever.

 

Pull off the cover, and darken the room. Raise and lower the offending lever, and see if you see a spark when the mercury toggels back and forth.

 

These are pretty simple, low tech switches, so if there is no spark, there is most likely a broken connection or loose terminal somewhere. OR, the heat sensitive spring that tilts the bulb back and forth at your setpoint may be broken or worn out.

"You know the Bill of Rights is serving its purpose when it protects things you wish it didn't."

 

"You can no longer be oppressed if you are not afraid anymore - Unknown"

 

SOL Member #174

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View PostHave one that is very similiar that is made by Sears.....

 

I am assuming the heat doesn't fire up even if you raise the High setpoint lever?

 

On mine at least, there are TWO mercury bulbs in there, one for each lever.

 

Pull off the cover, and darken the room. Raise and lower the offending lever, and see if you see a spark when the mercury toggels back and forth.

 

These are pretty simple, low tech switches, so if there is no spark, there is most likely a broken connection or loose terminal somewhere. OR, the heat sensitive spring that tilts the bulb back and forth at your setpoint may be broken or worn out.

 

 

you're right- the high set lever has no effect at all

 

good idea about darkening the room- i'll try that tonight

 

i looked at the wires quickly at lunchtime but didn't see anything obvious

 

i very much like the idea of moving a lever versus farting with a cheap touchpad or button with a digital display

 

but that's just me

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View Postif you are going to replace the thermostat stick with Honeywell and don't buy the cheapest one you can find.wink.gif

 

 

 

yup- i looked at it last night- no loose wires that i can see

 

and no visible spark from the mercury switch on the high setpoint side

 

guess i'll dismount it and look at the junction plate

 

then i'll go buy a new one if need be

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View PostThe point of which the spark occurs may have deposits making it not conductive. Possibly use an eraser or cotton swap with alcohol.

 

 

tough to do inside of a sealed mercury switch.

 

on the thermostat the OP described with the red and blue levers only one of them would be active at a time depending on what color dot was showing through the little window in the front cover. if the motor for the clock dies or the pins on the clock dial fall out it will never switch from the red to blue or blue to red lever.

 

with the age of the thermostat your better off just replacing it.wink.gif

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View Poston the thermostat the OP described with the red and blue levers only one of them would be active at a time depending on what color dot was showing through the little window in the front cover. if the motor for the clock dies or the pins on the clock dial fall out it will never switch from the red to blue or blue to red lever.

 

 

 

This is a good point that I didn't think of until just now redface.gif.........and may be why you didn't see a spark.

 

 

The clock on mine is battery operated, and every so often, the battery dies........

"You know the Bill of Rights is serving its purpose when it protects things you wish it didn't."

 

"You can no longer be oppressed if you are not afraid anymore - Unknown"

 

SOL Member #174

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View Posttough to do inside of a sealed mercury switch.

 

on the thermostat the OP described with the red and blue levers only one of them would be active at a time depending on what color dot was showing through the little window in the front cover. if the motor for the clock dies or the pins on the clock dial fall out it will never switch from the red to blue or blue to red lever.

 

with the age of the thermostat your better off just replacing it.wink.gif

 

 

the clock function has not been in use

 

but i may have accidently switched it back on when i was monkeying with it

 

i will check that out before doing anything else

 

makes sense that only the cold setpoint would work if it was in timer mode

 

the batteries for the clock had leaked a little, so i will bypass it anyway

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Wait a second........if the clock is not functional, what exactly are the two setpoints accomplishing? headscratch.gif

 

For example, on mine I set the blue (low) for 58 degrees. I set the red (high) for 64 degrees. The timer is set for blue from about 8 PM to 4 AM, and from about 7 AM to about 3:30 PM. The timer is set for red for the other times (4 AM to 7 AM, 7:30 PM to 8 PM). (I also have another timer for weekends with different time sets, but forget that for the moment.)

 

At night and during the day, the heat only comes on when the thermostat reads below 58. Early mornings and early evenings, it comes on when the thermostat reads below 64. Without a functioning timer, none of this would work, and it would be a single setpoint thermostat.

"You know the Bill of Rights is serving its purpose when it protects things you wish it didn't."

 

"You can no longer be oppressed if you are not afraid anymore - Unknown"

 

SOL Member #174

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View PostWait a second........if the clock is not functional, what exactly are the two setpoints accomplishing? headscratch.gif

 

For example, on mine I set the blue (low) for 58 degrees. I set the red (high) for 64 degrees. The timer is set for blue from about 8 PM to 4 AM, and from about 7 AM to about 3:30 PM. The timer is set for red for the other times (4 AM to 7 AM, 7:30 PM to 8 PM). (I also have another timer for weekends with different time sets, but forget that for the moment.)

 

At night and during the day, the heat only comes on when the thermostat reads below 58. Early mornings and early evenings, it comes on when the thermostat reads below 64. Without a functioning timer, none of this would work, and it would be a single setpoint thermostat.

 

 

there is a knob you turn that takes the clock off-line, which how mine has been for quite a while

 

in that mode, the blue lever kicks the heat on when the temp drops to 55

 

when we are out, we put the red lever parallel to the red one, effectively shutting the furnace off

 

when we come home, we move the red lever up to the desired temp, and the heat goes on until the desired high temp is reached

 

the red lever seems to have stopped making the heat come on at all, so i have had to move the red one up to get the heat to kick on

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Few typos in that I think, but I get the idea......and basically what you are saying is that the "programable function" hasn't done a thing for you in years, as you still need to move the red lever when you go out (or go to bed). And now the red lever isn't working anymore......so just use the blue one, you will accomplish the same thing you have been doing all along......wink.gif

"You know the Bill of Rights is serving its purpose when it protects things you wish it didn't."

 

"You can no longer be oppressed if you are not afraid anymore - Unknown"

 

SOL Member #174

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View PostFew typos in that I think, but I get the idea......and basically what you are saying is that the "programable function" hasn't done a thing for you in years, as you still need to move the red lever when you go out (or go to bed). And now the red lever isn't working anymore......so just use the blue one, you will accomplish the same thing you have been doing all along......wink.gif

 

 

yup

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