This isn't really a plumbing question but I wasn't sure where to put it. I always leave my northern Minnesota home for a month or three each winter. I usually leave the backup fuel oil furnace on, set for about as low as it goes. This still burns lot of money and exposes me to risks like oil leaks, which having had one, I don't ever want to see again. . I also have an outdoor wood boiler with cast iron radiators in the house which is my main source of heat when I'm home. I open all the zone valves and let the run through the house, though there's no fire burning.

So its occurred to me that I could just shut everything except the boiler pump down, drain pipes (which I do anyway) put antifreeze in toilets and drains (which I do anyway), clear out all bottled liquids and just let er freeze.
The things that concern me most are the wood boiler, when the house has heat that keeps the boiler water well above freezing. Can I be sure that it won't freeze if the house isn't heated and the pump is running? The other biggest concern is my hot water tank rusting if I leave it empty for a couple months.

Aside from those 2, there may be many other things to worry about that i haven't thought of, which is why I'm posting. What else do I need to orry about? Should I just forget this dumb idea?

 

if the pump pipes are insulated and don't run along a cold exposed wall getting blasted by the winter winds running the pump without heating it the water won't freeze... but you still have to consider the water make up to that system.or do you shut it down so it runs as a sealed system....how does the sun swing on the house in the winter thats a heating source..for the overnight...this is just a comment on your saving the money....proof of a cold winter and a random visit would prove your no heat pump only test...

 

If you have no heat running, you should drain water from all systems. Even with the pump running, that water is going to freeze. Minnesota gets pretty cold in the winter. Your radiators will crack if you leave any water in them and it freezes. I wouldn't worry about your hot water heater. The domestic water has oxygen in it so it always is rusting.

You could always switch over to a system that has antifreeze in it. Base on posts in this forum, it needs to properly maintained to make sure the ph doesn't go way off. But this may prove to be easier for you and better piece of mind.

 

Northern Minnesoada... yeah, I wouldn't trust the pump running to prevent a freeze up either... especially since that would depend on there being electricity to run it... agree with droo... drain it or cryotek it...

 

Since you stated that a minimal heat source was still very expensive, I would guess the house is not well insulated. With a home that gets cold easily, turning off the heat can become a problem if you forget just one thing.

I'm in a similar climate and deal with a lot of very old poorly insulated homes and this question comes up often. from foundations to condensation, there have been issues with letting a house freeze. If you improve the insulation and other related wx factors, then just a small heat source will keep everything above the problem level, at least until the power goes out.

Bud