Home Nest Replacement - No C Wire!

[whyrichard]

Hello,

Nest is dying… No C wire!

I am looking for a HomeKit compatible smart thermostats that only takes two wires… i have an old house and rewiring the thermostat will be diffficult and expensive….

Can anyone recommend a HomeKit compatible thermostat which doesn’t require a C wire?

A google search comes up with a bunch of thermostats which actually are either not HomeKit compatible or require a c wire… so is a dead end.

Anyone here can recommend and advise?

Thank you!
R

 

[chabig]

It's not hard to rig up a power adapter to a nearby outlet. I fished a wire from my thermostat to the air handler closet where I pulled power from the air handler. But even using a simple AC adapter works.

How To Install Smart Thermostat Without C Wire: Step-by-Step Guide For Any Home - TheHomeWiser

Setting up a smart thermostat can quickly upgrade your home's comfort and energy savings, but not every house has the wiring these devices need. If your

thehomewiser.com

But if you don't want to do that:

The 9 Best Smart Thermostats You Can Install Without a C Wire

Smart thermostats boast many useful features to control your energy usage. Here are some options you can consider that don't require a C wire.

www.makeuseof.com

 

[TonyC28]

I know you didn’t ask for this advice, but I was in the same boat once so I added a c wire myself. It’s super easy if you have some basic skills. Might be worth considering so you don’t have to limit your options.

 

[cynics]

First verify there isn't an extra unused conductor in the thermostat wire. Often times there is, you would just need to connect that extra wire to common (C) at the furnace and at the the new thermostat.

Ecobee makes a nice HomeKit thermostat that can be purchased with a power extender kit (PEK). The PEK is connected to 5 wires at the furnace and can multiplex to use 4 wires at the thermostat.

Honeywell and AprilAire also make thermostats with equipment interface modules (EIM). The thermostat on the wall is telling the EIM at the furnace what to do. This only requires 2 conductors (Honeywell) or 3 conductors (AprilAire) at the thermostat. The benefit here is you can tie everything into the EIM, ventilators, humidifiers, dehumidifiers, etc they aren't cheap though.

Btw I'm assuming you have Gas/Oil heat since most heat pumps thermostats have used common for decades.