Electronic Thermostat's

Anyone ever install one of these?

I’ve got a home with a two wire old mercury switch style thermostat. I’m trying to upgrade to an electronic one. It seems so simple from the instructions, just connect the wires. There ARE only two of them so it should be easy…lol

I’ve tried everything I can think of to get this thing to work. When I hook it up and turn the power back on I get nothing showing me on the thermostat that it’s getting power and my gas furnace just runs and runs trying to ignite. If I switch wire combinations it’s the same thing.

I’ve put the old one back on and it fires up right away without problem.

Anyone got any helpful thoughts?


I installed one a couple of years ago, same deal, two wires.

Didn’t have any problems.

Why are you turning the power off? Is it battery-operated?

Is there a manual override on it? Can you set the temp to like 30C and see what happens?

Mine has a delay (maybe 20-30 seconds) between it clicking and the furnace cutting in.

I meant turning the power off to the furnace before I connect the two wires up.

My biggest problem is that it doesn’t seem to be getting any power to the thermostat. When I connect the wires and flip the breakers back on the LCD on the unit shows me nothing. This is the second unit I’ve tried with the same thing happening.

I find it amusing I can build a computer from scraps but can’t get a two-wire install to work…hehe


Does it take batteries? Mine does.

I installed a programmable thermostat a few years back. It has a battery compartment, but that was just for running the clock and saving any settings that were programmed into the unit.

I don’t know what to suggest as far as getting it to work. I just followed the instructions (which were actually pretty lame), made a note of where the wires connected on the old unit, and attatched them in the same configuration on the new unit. Pretty tough to screw up, even for someone who can build a computer MacGyver-style.

I would suggest checking for a battery compartment before anything.

Well, unless you have more than two wires, then you’ll need some way of powering the thermostat.

Mine has the option of being powered by the furnace itself (24 volts? something like that), but I’d have to run a couple of more wires from the furnace up to the thermostat. It’s easier to just drop in a couple of AA batteries (which last a couple of years).

The thermostat definitely needs power to work – if the desired temperature is above the current temperature, it closes the circuit of the two wires you currently have running into the thermostat. That will turn on the furnace. If the desired temperature is at or below the current temperature, then it opens the circuit. Or vice-versa, I dunno. But the two wires themselves don’t carry the power to run the thermostat.

What MiG said. You need some batteries!

Well that’s pretty damn weird then because nowhere does it state it needs batteries and there is no place to put them. Now I’ll grant you that the installation instructions suck ass, but it just shows that you connect the two wires and all is good.

Thanks for the replies everyone.


What’s the model type / number?

Well I finally figured it out. Turns out I bought the thermostat that is for a 240V system. That’s pretty hard to run on a 24v setup. I should have paid more attention when I bought it and I would have seen that pesky extra zero.


Oh well - at least that’s better than buying the 24V version for a 240V furnace system - then you would have got Poof Sizzle Sizzle rather than nothing at all …