FAST-STAT Common Maker Thermostat Wire Extender (Adds a Common "C" Connection)

5 stars for being simple, but this requires a "C" connection at your furnace/boiler to connect to. Mine had T1, T2 only. So be careful. This only takes an existing "C" on your furnace and gets it via your existing wiring to your thermostat. It does not "create" a C wire out of nothing. I needed a C for my Ecobee4, and unfortunately had to return as this was 100% unclear.If you don't have a C connection on your furnace you must buy an external 24V AC transformer, like Elk TRG2440 24VAC, 40 VA AC Transformer with PTC Fuse. The Fast-Stat Common Maker won't solve this, nor will Ecobee's provided PEK kit.

Perhaps this product works for other situations or thermostats, however it did not work in two separate situations where I installed two NEST thermostats. I attempted to install on two different types of boiler heating systems, one conventional with zone valve and another with a dry contact relay and zone valve.I checked the wiring over many times and went through the troubleshooting steps for both situations. The NEST thermostat that was installed on the straight forward zone valve installation (no relay) seemed to recognize the Common, W and Rh and power up properly, except it would not open the zone valve when calling for heat. I even jumped the W & Rh wires at the thermostat location to open the zone valve and it still did not respond. Which means that it has nothing to do with the NEST.I called Nordic tech support and left my call-back info and never received a call back. Not sure if they were busy or out of the office.I'm still not sure about this product, but I would love to talk to tech support and figure it out.I purchased a total of six for customer installations and will be returning the four I did not open.

This is a terrific product. I was replacing my thermostats with the Honeywell TH9320WF5003 Wi-Fi 9000 Color Touch Screen Programmable Thermostat, 3.5 x 4.5- Inch, White and in two locations I was dealing with only 2 wire thermostat wire. Rather than the difficult task of snaking new wiring in order to add the third "C" wire needed for Wifi thermostats, I installed this. Very easy installation, the "sender" end that attaches at the thermostat location is quite small and is designed to hang inside the wall cavity behind the thermostat; I increased the existing wire hole in the drywall behind the thermostat location with a keyhole saw and after making the wire connections the sender slides right in. I wired it according to the applicable diagram and it works perfectly. In my case, I needed to add a 24 volt transformer in the basement next to my valve control boxes to power my "C" wires (several of my heating zones terminate at a Taco zone control box, not at the boiler/furnace/air handler, so I needed to add 24 volt power for the "C" wire). The wiring diagram for this type of application is shown in the product listing pictures above, called "dry contact switching." Very happy with this purchase, works perfectly, buying another!

A few months ago I bought two Honeywell Lyric thermostats for my multi-zone home which runs hydronic heat through a boiler and 4 zone valves. The Lyric's are advertised to be able to operate without a common wire, however as I quickly learned this would place unnecessary stress on the zone valves as the thermostats would steal too much power away from the zone control box and force the boiler to short cycle. This was a problem as it wore out a zone control valve ($80 part) and also the house was very slow to heat as the zone would come on for a minute then shut off for a minute and continue this cycle until the desired temperature was reached at the thermomstat. I was upset that I had spent $400 on two thermostats that wouldn't work. Determined not to give up on my investment, I started the process of determining how I was going to rewire 4 thermostats in my house just to get a common wire. My future plans are to replace the other two thermostats with Lyrics as well. This became a very daunting project to think about and just when I was ready to pull the trigger on rewiring, I ran across this on Amazon! Oh man was I excited to discover that this product existed! I ordered two and they were delivered today and installed them both. Took me about an hour to figure out the correct wiring with my Taco zone control panel but through trial and error it finally fired up the thermostats (and furnace) in full glory! I am so impressed by this product! I will be ordering two more when the time comes. If this doesn't work for you, you're either not wiring it correctly or need a 24vac external transformer like in the instructions. Don't give up on having a smart thermostat! This will solve all your problems!!

Works as advertised and included easy-to-follow instructions for someone who is already familiar with wiring a thermostat. The larger of the two black boxes that connects to your furnace includes double-sided adhesive to conveniently attach it next to your controller board. The smaller black box needs to go inside your wall behind your thermostat, so you'll need to make the hole big enough to slide it into the wall. If you're not comfortable doing your own wiring and following the included wiring diagrams, it's probably best to hire a trained technician.A C-wire or common wire is required to power most Wi-Fi thermostats, as it provides the necessary power to maintain a Wi-Fi connection even when the heating/cooling system is not running. I installed this unit with a Honeywell Lyric, which enabled the Apple HomeKit feature on that thermostat.Just a reminder: Check your existing thermostat wiring for an extra unused wire. It's possible that whoever installed your thermostat never connected a C-wire, and all you need to do is use a spare wire to connect it to the common terminal on your controller board. If you have a spare wire, you don't need this product.