New Wi-Fi thermostats are available that allow you to remotely control the temperature in your home. Unlike other battery powered programmable thermostats, these new thermostats can't run on batteries alone and even if they can they will drain the battery quickly. It's therefor necessary to connect a "C" wire to these thermostats to provide power. This post details how I provided power to my thermostat that didn't have a C wire running to it by using a plug-in 24 volt AC transformer. With a C wire powering your thermostat you won't need to worry about the batteries dying and you can set the light on your thermostat to be always on to act as a nightlight. The thermostat I was replacing only controls my gas fired, hot water boiler which provides heat only. I didn't have to worry about cooling as my AC unit runs off a separate thermostat. There were three wires coming out of the wall where my old thermostat was mounted. My heating system only requires two wires, R and W, to operate. I thought I could use the third wire to power my thermostat and use that as the C wire.

Unfortunately I ran into a couple of problems. First, there wiring was very old and there appeared to be a break in that third wire. I couldn't get current to flow to it from the basement. Second, and probably most importantly, I called the manufacturer of my boiler to double check that it would be okay to connect the thermostat to the C terminal on the 24 volt AC transformer in the boiler. These types of thermostats are called "power stealing" thermostats and the manufacturer (Weil McLain) does not recommend using a power stealing thermostat with my boiler. They were worried that the additional load from the thermostat may cause the transformer to prematurely burn out. They recommend using a separate 24 vac transformer to power the thermostat. The instructions for the Honeywell Wi-Fi Programmable Touchscreen Thermostat (RTH8580WF1007/U) I was installing didn't specify how to hook up an external power supply to the thermostat but calling customer service I was able to find out how to attach an external transformer.

If your thermostat is also controlling your cooling system or you have a different type of heating system the configuration might be different. It's a good idea to call the manufacturer of your thermostat and get specific instructions for your model and HVAC unit. Update: wi-fi on the thermostat sucks. You can only update the thermostat provided the thermostat can connect to the internet. how to install a 3 ton ac unitHurricane Sandy caused me to lose my home internet but I still had power and heat. price of 2 ton ac unitWhen I went to bed the following night I was chilled do the bone having been outside most of the day dealing with the aftermath and i wanted to turn up the heat without getting out of bed but i couldn't because my internet was down. air conditioning unit interior

I could access all other wired and wireless devices on my network, just no internet access. There is no way to connect to the thermostat directly. It is all done through Honeywell's cloud service which it turns out collects my homes temperature readings and heating system information every 12 seconds. I don't like that and i don't like not being able to access the thermostat from home when my internet is down. Change Your Thermostat Before It Gets Cold New Thermostat (I used a Honeywell RTH8580WF) 24 Volt AC plug-in transformer (I used an MGT-2440) 18 gauge thermostat wire. Number of conductors should be at least the amount of wires coming up from your HVAC system + 2 for the transformer. I needed a total of 4 conductors so I purchased the Southwire 50 ft. 18/2-Gauge Thermostat Wire 64162179. You may need more or less depending on how far you have to run the wire. 4 Wire nuts (one for each conductor you'll be using). Small ones, yellow or orange should do it.

Needle nose pliers with wire cutter Wire stripper (if you're not comfortable stripping wire with a wire cutter) Precision flat-head screwdriver (Like from the Stanley 66-039 6-Piece Jewelers Precision Screwdriver Set) Fish Tape (I used Gardner Bender EFT-21PN 25-Foot Cable Snake Steel Fish Tape) Step 1: Plan Your Wiring I could have continued to use the 2 thermostat wires that were in my wall plus add 2 more wires that will run outside the wall to a nearby outlet where I would plug in the 24vac transformer. I didn't like this setup because I didn't want the wire to the transformer exposed where the thermostat was mounted. The installation would look much cleaner if all the wiring ran through the wall as it did previously. I needed 4 conductors. Two from the boiler and 2 from the 24vac transformer. The closest wire I could find was 5 conductor thermostat wire which is what I used. I was going to run the 5 conductor wire from my thermostat down to my basement and then I'd splice 2 more cables in the basement.

One set of 2 conductors going to the boiler and two more going to the transformer which will be plugged into a wall. I used the same 5 conductor wire throughout (except for the connection between the boiler and new wire where I used the existing 3 conductor wire). There is no standard color coding for thermostat wiring. I decided to use the following convention. R - Red, W - White, Rc - Yellow, C - Blue. The yellow and blue wires will go to the transformer and since it's an AC transformer they could be switched. The 5 conductor wire will be snaked down the wall into my basement. From there I'll separate it into two runs. The Red and White will connect to an existing wire in my basement that goes into my boiler and connects to the R and W terminals on my boiler. The Yellow and Blue wires will run along another wire that goes to the plug-in 24vac transformer that will be plugged into a nearby outlet in the basement. Step 2: Turn Off Your HVAC System Before doing anything turn off the power to your HVAC system.

This will vary by system but there should be some sort of switch near your system or there might be a breaker specifically labeled in your main circuit breaker panel. Step 3: Remove Old Thermostat Step 4: Run New Thermostat Wire This is the tricky part and how you run your wire is going to depend on how your existing wire is run. I was lucky and my thermostat had a straight run down the wall it was installed on down to my basement. By pulling on the wire from upstairs and down in the basement I was able to tell that the wire was not firmly stapled to the wall and I'd be able to pull it right out. The types of fasteners I saw used in the basement were fairly loose fitting. If that's not the case for you you might have a harder time snaking the new wire. You might have to make small holes in your walls here or there. Fishing wire can be tricky and you might want to hire an electrician to do this for you. Remember, it's best not to try and tackle this when it's very cold and you don't want to be without heat for a couple of days if something goes wrong.

The first time I ever used the GB Fish Tape it was very difficult to get it out of the reel. You're supposed to pull the steel tape out by hand. It's coated in oil which makes it tricky. I took the tape outdoors, don't do this on carpet or the oil will stain it, and pulled out as much of the tape as I could by hand. Then I stepped on the end and pulled on the reel slowly working all the tape out. As my reach wasn't sufficient I walked down the tape to change where I was putting pressure. Be careful not to severely bend the steel tape when doing this. One I got all the tape out I reeled it in and repeated the processes. Now whenever I use the fish tape it comes out effortlessly. Attach Wire to Fish Tape Attach New Wire To Fish Tape Pull New Wire Up Through Wall Step 5: Connect Wires to Thermostat Base Plate R - Red (to boiler) W - White (to boiler) Rc - Yellow (to transformer) C - Blue (to transformer) Step 6: Connect Thermostat To Transformer