# Programmable Wi-Fi Thermostats



## DianaKaye (Oct 15, 2017)

I'm currently looking into getting two of these. We have a regular furnace on one side of the house and a heat pump on the other. Unfortunately, the house is not well insulated and we're trying to identify and fix heat loss areas. My husband and I are both retired, but leave the house for several hours at a time without turning the thermostat down. Sometimes, we forget to turn the thermostat down at night. 
I went to my daughter's side of the house (heat pump) and the thermostat was set at 72 during the day when she was working and her bill runs high. 

I'm looking for something that's Wi-Fi, has geo-fencing, can control with an app on one or more phones. Any suggestions for ones you really like and why? Thanks in advance!


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## DianaKaye (Oct 15, 2017)

I hope this helps. It's pictures of our main thermostat. Please let me know if you have one you like! Thanks! Diane


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## CaptTom (Dec 31, 2017)

I just put in 3 WiFi thermostats. Mine were Honeywell units and the app does not support geofencing, so you'd be looking at something with a larger feature set like a Nest of Ecobee. But I have done a little research, and learned a little. Let me take a stab at figuring out your existing t-stat.

It looks like it's set up for heating and cooling. RC and RH (24V power) are jumpered, so it must be the same transformer feeds both heat and cool. I'm guessing one unit does both.

The "W" terminal controls the heat, "Y" the cooling. "G" controls the fan.

You don't have a "C" wire, so there's no neutral ("common") wire to power a WiFi thermostat. Depending on your configuration, you might be able to use the "G" wire and let the heat/AC unit control the fan operation.

There are WiFi thermostats which don't require a "C" wire, but there's usually a down side, like short battery life or the need to install a dedicated transformer. Ideally, if you could fish another wire through from your furnace controls you'd be better off.

How'd I do?


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## DianaKaye (Oct 15, 2017)

Awesome! Thanks so much. I was looking at the Nest installations and it asked for my wires. I could just see a W, AC, G and Y. Hmmm, it's a pretty old furnace and runs on freon. The previous owner refilled the freon when we moved in as it wasn't working. Will have to think about what I want to do. Definitely appreciate the help!


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## CaptTom (Dec 31, 2017)

Just to be clear, your furnace DOES have a "C" terminal. Somewhere. It may not be labeled as such. If you can fish a wire from your furnace, you can use any WiFi thermostat you want.

The "C" wire is the "other" side of the transformer from the "R" wires (RC in your case.) 

The HVAC controls run on 24VAC. Just like your 120VAC outlets, there's a "hot" and a "neutral" side. 

A traditional thermostat is just a switch. It takes the 24VAC from the "R" wire or wires, and sends it along the "W", "Y" and/or "G" wires as appropriate, to power the heat, cooling and/or fan.

The smart thermostat needs power. It can get the "hot" side from the "R" wires, but to power a circuit, you also need the "neutral" side.

I called the manufacturer of my zone valve controller (where my 24VAC transformer lives) and they were happy to tell me which terminal was the best place to connect "C." Then it was just the tedious job of fishing the wire.


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## user_12345a (Nov 23, 2014)

> I went to my daughter's side of the house (heat pump) and the thermostat was set at 72 during the day when she was working and her bill runs high.


It will be even higher if the stat is lowered during the day, recovery causes aux heat to come on.

In a cold winter climate, the bills will always be high running a heatpump with aux heat. The heatpump itself can be economical but the aux heat use offsets that.

Much better to have a heatpump if it's going to be all electric - probably saving 30 to 50% compared to heat strips alone, but it's still not an economical system to operate.


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## DianaKaye (Oct 15, 2017)

So I've heard some heat pumps will work with a wi-fi thermostat and some don't. I haven't learned whether ours does or not. We live outside Atlanta and the first arctic blast gave us 10-12" of snow and bitter weather. The second one wasn't so bad, 1" of snow. Hopefully, we're back to our typical "rainy season" vs. winter. 
How can I tell if it's being efficient? The bill over there has been about $150 to heat one really large bedroom and a medium-sized bedroom, two bathrooms, living room, small dining room and really small kitchen. When the power company energy auditor came, she said our main heating bill was average for 3 people, then we found out that her heat pump is not on our electric bill (which covers the entire house!). I just find it confusing. Of course, I don't want anyone at a store selling me a wi-fi thermostat for a heat pump if the result isn't efficient. Thanks so much!


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## user_12345a (Nov 23, 2014)

The issue is that heatpumps lack capacity to raise the temp rapidly, so it's better to just leave them at a constant setting.

As a rule of thumb when it's cold enough for the heatpump to run continuously,it won't have the surplus capacity needed to raise the temp.

When it's in the mid 40s and above the house can probably be reheated without wasting energy on aux heat.

It takes a good stat like the ecobee to lock out the aux heat above a certain temp and for recovery.

Personally i think only fossil fuel and straight electric furnaces should be set back. It doesn't work well with properly size a/c and heatpumps, they're good maintainers but don't have the capacity for rapid recovery, an hour or less.


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## Corro-Protec (Nov 25, 2019)

Personally, I installed the MYSA in one of my rooms to test it and I am pleasantly surprised. The installation guide was very well done but I can not say the same about the connections made by my electrician 10 years ago! :vs_laugh:

I do not know how she compares to others like Honeywell and Nest, but I'm satisfied!


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