Hvac help

[maxwell]

Upgrading my thermostat. Have a new Honeywell wifi thermostat. My old thermostat only had two wires. Hooked to R and W on my furnace panel. My new thermostat says I need a C wire 24v common. My system is HEAT only and I don't need to control the fan separately. There is a C terminal on the furnace panel. I am wondering if I need to run a separate wire for the c wire and have all 3 wires hooked up on the new thermostat. Or can I switch the R wire over to the C on the panel.

Thanks


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[jeffg463]

what model of honeywell is it Maxwell? If it's wifi does it have a wired sending unit to be mounted at the furnace and then a wireless 'stat?

 

[Twacked]

You have to bring a common wire up to the stat to "power" the stat. Will not work without. While ur at it you might as well pull up more control wires so you can control your fan from the stat as well. Do u plan on installing a/c? If u do you'll need some for that as well. Put in 18/6 you should be covered.

 

[maxwell]

what model of honeywell is it Maxwell? If it's wifi does it have a wired sending unit to be mounted at the furnace and then a wireless 'stat?

Nope by wifi I mean I can control it anywhere from my phone. Since IM hardly ever home.

It's a RTH9580WF


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[maxwell]

You have to bring a common wire up to the stat to "power" the stat. Will not work without. While ur at it you might as well pull up more control wires so you can control your fan from the stat as well. Do u plan on installing a/c? If u do you'll need some for that as well. Put in 18/6 you should be covered.

That's a good idea. I can use the old wire to pull the new stuff through the wall. Is it called 18/6 thermostat wire just at Home Depot or? I don't have plans for ac but you never know!


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[maxwell]

So if I'm understanding correctly I will need the c,r,w wires to control just the heat.

 

[Twacked]

The wire you want is called LVT. Chances are the existing 2 wire is stapled to the stud and you will not be able to pull with it. The LVT you want is 18 gauge/ 6 conductor. Hook up the g terminal as well and you'll be able to control the fan from the stat. And c,r,and w.

 

[hbar218]

if it has batteries in the stat you don't need a c wire, but if batteries die you will not have heat

 

[Twacked]

For the perticular stat you have, you need the common wire for the stat to function I've been installing these since they came out. If you can't get a common wire ran there is another honeywell stat that only requires 2 wires but it is way more expensive and the wifi gateway is a seperate component.

 

[sledneck_03]

Get the nest thermo stat .

 

[maxwell]

if it has batteries in the stat you don't need a c wire, but if batteries die you will not have heat

Read a lot of negative reviews about it....maybe it's better now. got this one working and very happy with it


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