What thermostat do you currently have? Do you have electric baseboard heat? Do you know if the thermostat is powered by a 24 V transformer?

These are line thermostats, 220 volt, no transformers, for baseboards. Honeywell is the brand.

Because they are 220 volt thermostats there are no batteries as the batteries will not provide enough power to run them is probably why they don't have them.

Easiest option is to replace with analog non-digital 220v thermostat but you won't have any programming abilities with this option.

The other option is to retro fit (change wiring among other things) the heating system to be used with a normal 24v programmable thermostat that has battery back up capability.

There is a possible work around but it depends if your Honeywell thermostat supports it. Set the thermostat to vacation mode with a low temperature. Then each day your are there in the winter do a temporary setting to 70 degrees for the number of hours you need it. If the power goes out while the thermostat is in the temporary setting, eventually it will complete and go into the vacation mode when the power is restored. I am not sure if this will work but it is worth investigating.

Brilliant! I have thermostat with an economy mode but it has a 5 hour limit on the program retention. I will look into a thermostat with 'vacation mode' setting. thanks so much!

Having difficulty finding the thermostat with the right options but when I contacted Honeywell they suggested a mechanical thermostat. Not my choice for energy or comfort given the wider swings in temperature but certainly a work-around. I will simply swap the digital thermostat for the mechanical one when the problem occurs. I can replace the mechanical thermostat when I return to the house. At least the temp. will have been where I wanted it.

The mechanical thermostat would be the most foolproof solution. The mechanical thermostats built 30-40 years ago were precise instruments and programmable. Unfortunately today's version are cheaply made with no programming features.

The choices for line voltage thermostats are limited unless you want to build a custom solution.

I went to digital thermostats because they deliver a small amount of heat constantly rather than all or nothing as did the old mechanical thermostats. I preferred the frequent sampling of the temp rather than allowing the temp to drop a few degrees. Did I get this right?

I don't understand the comment about delivering a small amount of heat constantly. The line voltage thermostats are basically electronic switches. They are either on or off. What could be happening is that the digital thermostat can switch on and off when the temperature drops by 0.5 degrees from the set point. A cheap mechanical thermostat probably has more temperature variation.

The Aube Technologies TH115 thermostat from Honeywell looks interesting. It has a vacation mode that you set by pushing a button. But that probably doesn't work during a power outage. But it has a wired remote control feature. The manual says that if the contacts of the wired remote are closed then the thermostat will be in vacation mode. I think it is meant to be used with a telephone line remote controller which Honeywell also sells. But maybe you could wire this to a simple switch which you would flip when you leave the house for extended periods of time. This is worth investigating.

Here is the Aube telephone controller. If you have a land line in the house then you could use this. But closing the connection manually with a switch is fine if you don't mind arriving at a cold house.

My understanding of the electronic thermostat is that it checks the temp many times/ minute and and turns on or off as needed. The effect of this is pulses of power coming on every few seconds. So 20 seconds of power in a minute would be 33% power and that appears as a bar graph on the thermostat. I realize it is on or off but the effect is a continuous partial power. This is just my understanding of what I have read, no actual knowledge!

The telephone control is interesting but no land line. Good thought.

Thanks for all the info. I did find an interesting unit at Home Depot.com. It is the 'Hunter 7-day Universal Digital Programmable Thermostat'. It offers the curious ability to remove the face after instillation so you can program it in the comfort of your easy chair. Unfortunately they don't ship to Canada but I will pick one up on our next trip south.

That's interesting that the thermostat shows how often it is turning on the electric heat. I am not not an expert on line voltage thermostats. I did not think they operated in this manner. It sounds like it uses a technique called pulse code modulation. It is similar to how a light dimmer operates. This works well with baseboard resistance heat. It is not appropriate for a furnace or boiler.

The thermostat I researched does not have to be controlled remotely with a landline. A simple on/off switch that you control manually could take the place of the remote control device. What I don't know if it will perform as well as your current thermostat when operating in normal mode.

What is the model number of your current Honeywell thermostat? Maybe there is a programming trick you can use the day before you plan to leave the house for a long period of time.

Don't have the model number til I visit the house. Will post when I get it. With the option of swapping the digital for a mechanical should the situation occur it has take the urgency out of the problem.