2
votes
1answer
24 views

How do I connect a C wire to an Utica PEG112CDE steam boiler?

I want to upgrade my old mercury thermostat that I currently have to a newer programmable thermostat. This little DIY project is for my first late 1920's home that I recently purchased. I currently ...
0
votes
2answers
61 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 ...
0
votes
0answers
79 views

Where to connect a c-wire on a furnace with existing two wire mercury thermostat

My existing thermostat is an old mercury two wire device, heat only. Looking to upgrade to a better model, but I need to run a c-wire. I don't know where to connect the wire at at the furnace, any ...
0
votes
1answer
268 views

Which terminal should be used for a “C” wire when none are labeled “C”? Older electric furnace/heat pump

I have an all electric air handler/furnace connected to a separate AC unit and it is also a heat pump. I've purchased the latest and greatest Honeywell WiFi "Smart" Thermostat and it needs a C wire. ...
1
vote
1answer
187 views

Where do I connect my C wire from my thermostat when there are two transformers?

I have a Laars gas boiler that has 3 heating zones. I want to replace the old mercury honeywell tstat on the 1st floor (heat only) with a newer honeywell RTH9580 wifi model. I've taken pictures of my ...
0
votes
0answers
18 views

Need to run a “C” wire to thermostat but control board has no “C” [duplicate]

I am looking to replace a thermostat with one that needs a C wire... which my current thermostat does not. I have some extra wires in the thermostat wiring that are unused... so I went down to the ...
1
vote
1answer
282 views

Where can I connect the C wire on the A/C side?

I’m trying to replace my thermostat with the Honeywell Smart-WiFi thermostat. Quick summary, I have an extra yellow wire which I’m making the C wire, but its not connected at the other end and I’m not ...
0
votes
2answers
372 views

Can I install a Honeywell WIFI Thermostat?

I have done quite a bit of research and have not been able to find an answer I am looking for. I currently have a manual digital thermostat that is not programmable made by Braeburn. My system is a ...
0
votes
4answers
3k views

HoneyWell Wifi Thermostat and C wire

I just bought the HoneyWell Wifi thermostat and so wanna use it. However my old Thermostat was battery powered and does not use the "C" wire. I opened up my panel and found that there were three ...
0
votes
1answer
926 views

Is it possible to use add-a-wire with my current configuration to add a C-Wire? [duplicate]

I only have four wires: Red, Blue, Yellow, and Green. My old thermostat jumps the R to RC and leaves C empty. I have a new thermostat that wants 5 wires, but I don't have C. I am not sure what the ...
1
vote
2answers
5k views

Adding a C wire to a new Honeywell WIfi Thermostat

I am trying to install a new Honeywell touchscreen WIFI thermostat (http://www.homedepot.com/p/Honeywell-Wi-Fi-Smart-Thermostat-RTH9580WF/203926327?N=5yc1vZc5kl) and need to add a C wire to my ...
0
votes
0answers
442 views

Please help establishing a C wire for new tstat

I bought a new WiFi tstat as a replacement. The tstat controls my second floor hot water baseboard heat and my central air conditioning. I've located all the wenter image description ...
1
vote
2answers
650 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 ...
0
votes
1answer
788 views

Need help running and connecting a 'C' wire to my new thermostat

I have a Laars gas boiler that has 3 heating zones; basement, 1st floor, and 2nd floor. I want to replace the old mercury honeywell tstats on the 1st and 2nd floor with newer honeywell RTH9580 wifi ...
0
votes
2answers
2k views

How can I modify a 4 wire thermostat to a new thermostat requiring c wire?

I attempted to replace my thermostat with a fancy new Trane z-wave enabled model. To my dismay my home was only wired with a 4 wire setup with no 5 hidden in the bundle. I followed Insx on the web ...
1
vote
1answer
735 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 ...
0
votes
1answer
3k views

Wireless Thermostat C-Wire Substitute

I've read How can I add a "C" wire to my thermostat? and checked out the Venstar Add-A-Wire Accessory. I've watched Honeywell's YouTube video on "DIY Wi-Fi Thermostat Substitute G-Wire for C-Wire," ...
1
vote
1answer
370 views

How do I connect a C-wire on a Triangle Tube Prestige Solo 110? [duplicate]

I purchased a Honeywell RTH6580WF to use with my recently installed Triangle Tube Prestige Solo 110 propane boiler. I only have two wires at my existing heat-only thermostat. I understand that the ...
0
votes
1answer
312 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 ...
1
vote
4answers
1k views

Can I provide a secondary power source for my thermostat?

The thermostat at my home is set up with only the 24 power and return through the relay. I would like to add a 'smart' thermostat, however the line is fairly well buried in the wall/basement ceiling ...
3
votes
2answers
533 views

Can I use an unused wire as a “C” wire?

I just bought a new thermostat that is Wi-Fi enabled and it requires connection to a "C" wire. The old thermostat does not have one running to it, but there are other unused wires. The thermostat ...
1
vote
2answers
2k views

Which terminal should I connect it to for a “C” wire when none are labeled “C”? [duplicate]

I am looking to replace my old battery operated thermostat with a new wifi model. There is no "C" common wire connected to my old thermostat. There is a blue wire that is at the thermostat but cut ...
0
votes
1answer
2k views

How do I add a C/ Common wire to my “Specific” HVAC system? [duplicate]

I just bought a new WiFi thermostat that requires me to add a C-Wire at the furnace. I have read the questions related to my issue but would like a suggestion on my particular (incredibly OLD) ...
0
votes
1answer
301 views

Thermostat C-wire replacement using a wall socket?

I have a Filtrete 3M WiFi thermostat. As expected, it takes a C wire, which my apartment doesn't have and the apartment maintenance folks wont' let met wire either. However, there's a wall socket ...
1
vote
1answer
562 views

How to wire a new Honeywell RTF6580WF thermostat to replace a Chronotherm IV?

I have an old Honeywell Chronotherm IV thermostat that I am trying to replace with a Honeywell RTF6580WF wifi thermostat. I have a gas furnace and an air conditioner. Wiring for Chronotherm IV ...
0
votes
1answer
343 views

How can I add a C-wire to a Venstar T5800 thermostat?

I am trying to replace my existing thermostat. My old thermostat has: Rh, W (coming from the heating unit). Rc, Y, G (coming from the AC unit). On the Venstar T5800, I can map as follows: Rh+Rc ...
11
votes
2answers
9k views

Why is my Nest thermostat not working with A/C?

I installed Nest thermostat a few weeks ago, replacing an old Lux programmable thermostat (there was nothing wrong with it). I connected 4 wires (R,W,Y and G) to the Nest. But as soon as I'd ...
1
vote
1answer
326 views

thermostat c wire question [duplicate]

I am looking to install a new thermostat that will require a C wire. I have a single stage A/C unit and my current thermostat has Rc, G, and Y wires. There is also an unused blue wire which I traced ...
4
votes
2answers
691 views

Connection for C wire on Mastertrol Mark V zone control panel

I have spent hours searching the web for information on this 20+ year old zone control panel, which supports 3 zones of Heat and A/C. The thermostat I'm replacing (on Zone 3) connects to T4/T5/T6 as ...
1
vote
2answers
1k views

Can you terminate more than one common on the furnace C terminal?

TL;DR: Can you terminate more than one common on the furnace C terminal? Background: I've linked a diagram of how my non-programmable thermostat is currently hooked up. I want to replace it with a ...
0
votes
3answers
3k views

How can I use a separate transformer to provide a C wire to my thermostat?

I Purchased the Honeywell WiFi Prog Thermostat to replace my Round Digital Honeywell Thermostat. I have separate Heating and Cooling (Heating is a Weil McLain Boiler for Hot water baseboard and Hot ...
3
votes
2answers
1k views

Is voltage too high in C wire going to thermostat?

I've managed to add a C wire to my thermostat. I then decided to check the voltage between the R and C wires, and find that it read as 27.8 volts, not the 24 volts it was supposed to be. Could this ...
1
vote
0answers
51 views

How can I add a common “C” wire to my thermostat? [duplicate]

Possible Duplicate: Options for adding “C” wire to thermostat I recently bought the Honeywell THM5320R Wireless thermostat. After going to hook it up I found what many others have, it ...
1
vote
1answer
2k views

How to connect Nest in Europe

I found a question regarding the Nest thermostat here. But that is only a question "Will it work?". Thanks to that I know it WILL, the problem is...HOW. I know the wire naming conventions are ...
0
votes
1answer
656 views

Options for adding “C” wire to thermostat [duplicate]

Possible Duplicate: Options for adding “C” wire to thermostat I am upgrading to a newer thermostat that requires a constant 24 volt feed, I have an extra (unsused) wire in the ...
2
votes
1answer
4k views

How can I add a “C” common wire to this system? [duplicate]

I would like to add a "C" / Common wire hookup to my hvac system and get a fancy new thermostat. I've read Options for adding "C" wire to thermostat and still have some questions. First of ...
34
votes
4answers
133k views

How can I add a “C” wire to my thermostat?

So, the spiffy new wi-fi thermostats want power on the C wire from thermostat, but the old thermostat doesn't have a C wire at it. What's the easiest way to add the C wire/24 volt to the thermostat ...
3
votes
2answers
2k views

Can I piggyback a thermostat with a C Wire hookup on a furnace?

I'm trying to install a new thermostat that needs a C wire hookup. There are currently 4 wires running from the thermostat to the furnace, none of them are a c wire. When I look at my furnace itself ...