Thermostat that works without batteries?

[Stephen Tashiro]

Is there a thermostat for a 2-stage heating/AC system that doesn't require batteries? - or will still work if the batteries go bad?

The best my contractor could do for a system with 2-stage heating and 2-stage cooling is to get a thermostat that will run the system correctly with dead batteries until there is a power outage. When the power comes back on, then the thermostat will run the system on its default setting, which is 1-stage heating and 1-stage cooling. I'd like to find a thermostat with the correct default setting - or, even better, to pick the default without relying on batteries to hold it (jumper switches or something like that).

[Steve Peterson]

Our thermostats use batteries and I think I may have changed one in 8 years in the 4 wall units. It is not nearly the same hassle as smoke detectors. For starters, there is an LCD screen that lets you know when it needs changing. Plus they are at a convenient height and ours uses simple AA batteries. I wouldn't worry about it.

Steve

[Brian Elfert]

The batteries in my Honeywell thermostat didn't last more than a year or two even with lithium AAs. Even though the thermostat is eye level I never noticed the low battery warning the last time the batteries died in May. Luckily, it died during a period with no heating or cooling requirements. I'm not sure if it would keep heating or cooling at the current temp when the batteries die.

[Shawn Pixley]

I don't actually know if there are currently, but there used to be thermostats that ran off a transformer rather than batteries. But I replace my batteries once a year on my 5+1+1 thermostat. I'm sure that the batteries are still good at that stage but I have it scheduled to check / replace at daylight savings time along with smoke detectors, CO2 detectors, fire extinguishers, clock resets, water filters, etc...

[David Weaver]

I have one of the old non-battery thermostats, but I have never seen one of my thermostat's style that would work with a two stage system. I'd have to imagine that it would be more expensive to make one of that type than it is to make a digital system, and the controls would be manual set instead of automatic.

I've had a digital thermostat in a pack to replace mine for a little over 8 years now.....but I won't do anything until I no longer have a single stage system.

[Tom Stenzel]

I've never seen such a thing in the wild. It could be built out of multiple single point thermostats but it would be expensive and the wiring would be a mess.

More to the point, what's driving the no battery requirement? With that information maybe someone could make a suggestion that will solve the root problem.

-Tom

[Stephen Tashiro]

what's driving the no battery requirement?

The thermostat is for a friend who hasn't learned to master new fangled gadgets like smart phones, remote controls to DVD players, and programmable thermostats. The friend doesn't keep track of how long batteries have been in things. I don't want to get a call at an inconvenient hour to drive across town and get the heat/AC working again after a power outage.

[Bruce Page]

Stephen, you sure have a lot of interesting friends.
I do like Shawn, I have a schedule.

[Tom Stenzel]

I did a quick Google using:

"programmable thermostat with non volatile memory"

There's a couple of companies that claim to have what you're looking for. I can't make a recommendation, I haven't any experience with these devices.

But no matter what you get, it seems that a thermostat with no battery or power would need the time set. I don't see any way to avoid that. Can your friend take care of that?
-Tom

[Brian Elfert]

If this is that much of an issue for your friend why not suggest a single stage system that can still use a non-battery thermostat? It will probably cost extra money in energy, but at least it will work as long as there is power.

[Dan Hintz]

I did a quick Google using:

"programmable thermostat with non volatile memory"

Non-volatile memory and "can run without batteries" are two different things. The former just means the program you spent two hours putting into it won't disappear when the battery runs out.

[Stephen Tashiro]

I did a quick Google using:

"programmable thermostat with non volatile memory"

I'll try that. Setting the time won't be important. My friend wouldn't use the programmable feature of the thermostat. It would always function in the "hold temperature" mode.

[Jason Roehl]

Sadly, this would be potentially MORE complex, but I have, this year, installed 3 Honeywell Wifi thermostats (2 standard LCD, one color touchscreen--the two are at my church, and the color touchscreen at home). They need an extra wire for power, but require no batteries. I do not know if the standard LCD models can handle a 2-stage system (I suspect they do, I just don't recall), but the color touchscreen model DOES work with 2-stage heating or cooling. I can thus monitor all 3 thermostats from my smartphone anywhere I can get data access via either a Wifi network or cell data services. There may be similar models available without the Wifi feature.

[Brian Elfert]

The Honeywell WI-FI thermostats are not exactly the most reliable from what I read. One of my co-workers thought his furnace had failed this winter, but his wife reset the thermostat somehow and things started working again.

[Tom Stenzel]

If it doesn't need to be programmable that changes things. Would a White Rodgers IF83-261 work for you? Two stages cooling two stages heating. To make it work without batteries the C wire must be connected to the 24 volt transformer.

The Honeywell T874 series would work too but at a much higher cost and ordering it with the correct options is more difficult. I can vouch for the Honeywell, we had one in our shop for 25 years, set up for 2 stage heat 1 stage cooling.

I can search more but need to saw off for now. At least you can have hope...

-Tom