Linked Questions

1 vote
1 answer
2k views

How to troubleshoot heat that's always on?

My boiler (Weil Mclain CGA Gold ~2003 install) failed the other day. After some help from a plumber and reading the manual, I replaced a few parts (more below) to get it running again. Now one zone is ...
Yann's user avatar
  • 111
1 vote
3 answers
2k views

Wifi Thermostat wiring

Replacing 2 Hunter thermostats with a Honeywell RTH9580 Wifi. Neither unit has a C wire - I'm comfortable with the upstairs high efficiency unit, but the downstairs older unit has thrown me for a loop....
Chris's user avatar
  • 11
0 votes
1 answer
2k views

Can I share "C" wire on two thermostats?

I am wiring a second thermostat right next to the original one. The new needs a C wire. Can I share it from the old one? Old: 8 wires, used to run heat pump (w/ heating and AC) and backup oil. Now ...
mankoff's user avatar
  • 514
2 votes
2 answers
1k views

Can I pull a common wire off an evaporative cooler transformer relay?

I have a Nest thermostat currently controlling a LP furnace. The old thermostat didn't have a common wire connected, but there was a an extra wire in the bundle and a common terminal on the furnace ...
Matt's user avatar
  • 183
0 votes
1 answer
2k views

Add C wire to very old gas furnace

There is a very old gas furnace in our attic. It has a two-wire transformer and no obvious terminals to expand. I need to run a C wire to my nest thermostat, which I'm planning to do via their nest ...
justinbelcher's user avatar
1 vote
1 answer
1k views

How to connect a new C wire

I have a 2 zone, single stage, heat only system with 2 wires running to each thermostat. I'm looking to install 2 Ecobee's; I have a second Honeywell AT72D1683 that I can install if needed and have ...
Aaron Ricci's user avatar
0 votes
1 answer
2k views

Why does my A/C "bump" and cycle super fast at night?

I've got an ancient Armstrong Concept 1000 air conditioner (it was old when we bought the house 11 years ago) hooked up to a Nest thermostat. The furnance and blower is much more modern; it's an Aire-...
Nate's user avatar
  • 133
0 votes
2 answers
1k views

Where to attach the "C" wire to my furnace?

I am upgrading to a new thermostat which requires a "c" wire to power it. I have an unused blue wire running from my thermostat to my furnace that I plan to use as the common wire. However, I am ...
Josh C's user avatar
  • 3
0 votes
1 answer
2k views

How to connect a DIY thermostat to the HVAC System

I am building a DIY thermostat similar to this blog. I want to connect it to the HVAC system of my home. How do I do that? I found this post which is very informative but doesn't completely answer my ...
nad's user avatar
  • 101
1 vote
3 answers
1k views

Cannot figure out wiring of most basic Honeywell thermostat (heater only)

I live in an apartment with central heat. It's controlled by a round Honeywell thermostat. The heater ticks really loudly and annoyingly when it heats up and cools down (probably a topic for a ...
Philip's user avatar
  • 481
0 votes
1 answer
2k views

How can I install a Honeywell RTH65800WF Wifi thermostat?

I am having some difficulty figuring out the correct wiring for my new wifi thermostat. Before I bring out the A/C technician, I was wondering if anyone here might be able to help? Searched other ...
Hugh's user avatar
  • 3
1 vote
0 answers
2k views

Problem connection C wire into Lennox Furnace

I would like to connect my new Honeywell WiFi thermostat (RTH6580WF1001) to a Lennox Elite dual Heater and Cooler system. I don’t have a C wire in my old thermostat. I have read online that I can ...
Antonio Monserrat's user avatar
1 vote
1 answer
1k views

Needing Help with new thermostat install (C Wire)

I am in the process of installing a new thermostat that requires a c wire. I checked my thermostat to see if it has a c wire running to it and it does not. After doing lots of googling and watching ...
Jeremy's user avatar
  • 11
1 vote
1 answer
1k views

Need to add common "C" for thermostat; can anyone indicate where to connect it?

We just got a new WiFi capable thermostat that, unfortunately, seems to use a form of power stealing in order to charge itself. The problem here is that our house is actually quite well insulated; the ...
Michael J.'s user avatar
0 votes
2 answers
1k views

No electricity going to thermostat

Our old thermostat is working but I want to change to a new one (nest thermostat). I have two exact HVAC unit at home. I change one it works but when I change the second one it doesn't work because ...
Cindy's user avatar
  • 1

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