It's fall, I'm trying to get a bunch of things done before winter sets
in.

My OLD Lennox Electric Forced air whole house heater (was installed in
1970) has the original Lennox Thermostat.

It's the round dial-type with a slider on top of the dial that you set
to desired temperature. Mercury bulb inside. It worked well until the
end of last winter, when I noticed that if I set it at 68 degrees, it
might go to 72 degrees or so until it shut down the heater.

Wifey has turned the heater back on and I am back with the beast not
shutting down at 68 degrees (Oh, it will occassionally, I think).

Anyway, is there a way to fix this....or do I just need to buy a new
thermostat. If I buy a new one, any suggestions? I do not want one
of the programmable "bells and whistles," model.

Just another basic would be fine. Meanwhile, wife is very happy with
the heater shutting off in the mid-70s range...me, not so much.

Snap the round cover off. There are places to prop a spirit
level, if the stat is tilted, it will perform high or low.
Make sure the stat is level to the earth.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"tim birr" wrote in message
...
It's fall, I'm trying to get a bunch of things done before
winter sets
in.

My OLD Lennox Electric Forced air whole house heater (was
installed in
1970) has the original Lennox Thermostat.

It's the round dial-type with a slider on top of the dial
that you set
to desired temperature. Mercury bulb inside. It worked well
until the
end of last winter, when I noticed that if I set it at 68
degrees, it
might go to 72 degrees or so until it shut down the heater.

Wifey has turned the heater back on and I am back with the
beast not
shutting down at 68 degrees (Oh, it will occassionally, I
think).

Anyway, is there a way to fix this....or do I just need to
buy a new
thermostat. If I buy a new one, any suggestions? I do not
want one
of the programmable "bells and whistles," model.

Just another basic would be fine. Meanwhile, wife is very
happy with
the heater shutting off in the mid-70s range...me, not so
much.

tim birr wrote:
It's fall, I'm trying to get a bunch of things done before winter sets
in.

My OLD Lennox Electric Forced air whole house heater (was installed in
1970) has the original Lennox Thermostat.

It's the round dial-type with a slider on top of the dial that you set
to desired temperature. Mercury bulb inside. It worked well until the
end of last winter, when I noticed that if I set it at 68 degrees, it
might go to 72 degrees or so until it shut down the heater.

Wifey has turned the heater back on and I am back with the beast not
shutting down at 68 degrees (Oh, it will occassionally, I think).

Anyway, is there a way to fix this....or do I just need to buy a new
thermostat. If I buy a new one, any suggestions? I do not want one
of the programmable "bells and whistles," model.

Just another basic would be fine. Meanwhile, wife is very happy with
the heater shutting off in the mid-70s range...me, not so much.

make sure that whatever holds the mercury switch to the spring is not
letting it slide around. Dito for whatever holds the spring to the case.
Clean the gunk out of the spring (bi-metalic temp sensor).
As long as you don't break the glass, there's hardly anything
to go wring.

I got a programmable one with the new furnace. I started out
setting it back to 65 at night, but soon found that I was leaving
it at 65 all the time and manually poking it down lower if I'm feeling
too hot.
If your house is "leaky" and you're not home (predictably) most of
the time, timed setback might be useful.

On 10/31/2011 2:55 PM, tim birr wrote:
....

It's the round dial-type with a slider on top of the dial that you set
to desired temperature. Mercury bulb inside. It worked well until the
end of last winter, when I noticed that if I set it at 68 degrees, it
might go to 72 degrees or so until it shut down the heater.
....

Anyway, is there a way to fix this....or do I just need to buy a new
thermostat. If I buy a new one, any suggestions? I do not want one
of the programmable "bells and whistles," model.
....

You can try the cleaning mentioned, but it's not likely going to help.

If the mercury isn't nice and shiny any longer, it becomes more "sticky"
and it takes more to get it to flip, in effect increasing the
hysteresis. Happened to the old classic Honeywell here a year or so
ago; I put up with it until changed out the old system this year.

I looked some locally, the old-style are essentially a thing of the past
and while still possible, seemed that they were more expensive than the
inexpensive digitals. Contractor used a plain-vanilla White-Rodgers
(sp? "d" or no-d?) on these systems; seem fine. No idea what they are
cost-wise...

--

On Oct 31, 6:32*pm, dpb wrote:
On 10/31/2011 2:55 PM, tim birr wrote:
...

It's the round dial-type with a slider on top of the dial that you set
to desired temperature. Mercury bulb inside. *It worked well until the
end of last winter, when I noticed that if I set it at 68 degrees, it
might go to 72 degrees or so until it shut down the heater.

...

Anyway, is there a way to fix this....or do I just need to buy a new
thermostat. *If I buy a new one, any suggestions? *I do not want one
of the programmable "bells and whistles," model.

...

You can try the cleaning mentioned, but it's not likely going to help.

If the mercury isn't nice and shiny any longer, it becomes more "sticky"
and it takes more to get it to flip, in effect increasing the
hysteresis. *Happened to the old classic Honeywell here a year or so
ago; I put up with it until changed out the old system this year.

I looked some locally, the old-style are essentially a thing of the past
and while still possible, seemed that they were more expensive than the
inexpensive digitals. *Contractor used a plain-vanilla White-Rodgers
(sp? "d" or no-d?) on these systems; seem fine. *No idea what they are
cost-wise...

--

Seems like a cobweb would produce the flaky results the OP is seeing,

Well, I feel extra stupid.....I pulled off the front to try to check
level and clean out the 'stat, and I just realized, no mercury at
all. I am not sure what I was thinking about. I would have bet $100
cold that that was the construction.

Bi-metal coil controls the switch. Switch itself is actually encased
in a see-through plastic "case" so it is totally clean and as far as I
can tell contacts look fine.

I vac-ed dust off the coils. Not very cool tonight, so the unit is
shutdown, but it was not all that dirty, and appears level, so I
suppose it may be off to buy a new one.

Honeywell makes a basic digital, non-programmable, I may try. About
$90.

tim birr wrote:
Well, I feel extra stupid.....I pulled off the front to try to check
level and clean out the 'stat, and I just realized, no mercury at
all. I am not sure what I was thinking about. I would have bet $100
cold that that was the construction.

Bi-metal coil controls the switch. Switch itself is actually encased
in a see-through plastic "case" so it is totally clean and as far as I
can tell contacts look fine.

I vac-ed dust off the coils. Not very cool tonight, so the unit is
shutdown, but it was not all that dirty, and appears level, so I
suppose it may be off to buy a new one.

Honeywell makes a basic digital, non-programmable, I may try. About
$90.
Looking good is not adequate.
Clean the contacts.
I'd use a sliver of emory paper with IPA, followed by regular cotton
bond paper with IPA to get the grit outa there.

And there oughta be some sort of hysteresis in the assembly. Otherwise,
the contacts would just chatter and arc. Make sure that mechanism is
not gummed
up.