I would like to replace my thermostat in my apartment with a digital programmable thermostat. I don't have access to turn off the electricity to my HVAC system and I don't want to involve the landland (I can always change back the thermostat when I leave). Do most thermostats run off of a 120v power control? Is there any safe way to replace the thermostat without being able to cut electricity to the HVAC? Thanks
replacing a thermost without ability to turn off electricity
Sep 26, 2007
30 Replies
No. They run off of 24 volts. If you want to make sure, measure before touching the contacts, but they do. And so will the replacement thermostat.
All the thermostat is is a couple electronically controlled switches, plus an internal microprocessor. You should be able to take off the old one and put on the new one without touching any of the uninsulated portions of the wires and without letting any wire touch any other. Heck, some people change 110 volt fixtures without turning off the power.
If you do touch the wires, you probably won't be able to feel 24 volts, and it won't kill you.
If you let them touch each other, I don't think there is any pair that will hurt anything. More likely it will start the heat or ac.
But now is the time to learn how to do these things wihtout touching anything.
Make a detailed drawing of which wire is on which screw now, so you can put it back before you leave, and so you'll be able to figure out how to attach the new one.
yeah , right ,
short the wrong two together and he'll let the factory smoke out of the transformer , then the landlord will be involved ,
leave it alone ,or call the landlord and have them kill the power while you replace the stat ,
you'll be sorry !!!!!
mm wrote:
"let the factory smoke out of the transformer" ???
What does that mean? Is there a transformer that comes with smoke inside, installed by the factory?
your kidding right ? what turnip truck did you just fall off of ?
"JoeSpareBedroom" wrote:
"let the factory smoke out of the transformer"
There's no more power/electricty/danger/problem in changing out a thermostat than changing the batteries in some flashlights (24 volts, not 120).
Go for it.
Whether you'll like a programmable thermostat is another issue.
Forget your sense of humor this morning?
The "Let the smoke out" is often used for motor when it goes bad. They work well until you let the smoke out
Joe,
About 30 yrs ago I heard a joke about semiconductors. The joke was that they worked with smoke. If you hooked them up wrong or abused them the smoke escaped and they stopped working. Hope that clears up your confusion.
Dave M.
More likely 240, but then there would be an individual thermostat in each room. My parents' house has this, as there were no other utilities available when it was built. Heat is solely from large woodburning stove and 240V resistive baseboards.
nate
But you can buy replacement smoke:
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No, only 120. You need only to break one leg of the circuit to stop the heater from being "on".
I should have thought about that. Do they make programmable thermostats for such systems?
Don't just assume there is universal interchangeability between thermostats, particularly ones which as you indicate are controlling both heating AND air conditioning.
If I was your landlord I certainly wouldn't appreciate your screwing around with parts of the most expensive appliance I there without my knowledge and permission.
Is there some particular reason (other than your being cheap.) that you don't want to involve the landlord?
Jeff
keep on trollin !!!!!!! maybe you'll catch a bigger fish ,
"JoeSpareBedroom" wrote:
me thinks , he thinks that he gonna save some money , until he burns something up , cuz he apparently has no clue whats he's doing
then he'll be wondering about the economy of diy !
Jeff Wisnia wrote:
People replying here are making a lot of assumptions about what and how that thermostat controls your heating and AC. Also your questions indicates very little, if any, knowledge of electricity. Do you even have or know how to use a test voltmeter? There have been enough horror stories about people trying to hook up low voltage programmable thermostats directly to 230 volt lines; they burn up and are not returnable! Also line voltage thermostats to low voltage control circuits, they usually don't work! Had a son in law who tried that! he also manged to burn out the motor on his aire xchanger; some people and electrcity don't mix. If something doesn't work or burns out, even if thermostat seems to work OK during cooling but does not during heating season an expert will have to be called in anyway. Please make sure you know what you are doing, also safety!
That's not for you to decide.
Talk to your landlord.
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