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Community and Q&A

Backup heat source

funkytut | Posted in Building Code Questions on

I was under the impression that there was a northern Minnesota requirement to have a backup heat source.  When my home was built, I was told that the Steffes hydronic boiler that was installed at the time would satisfy the requirement because it stores heat.  
My questions:
Is this an actual requirement?
If so, is this about energy sources or about heat sources?

If it’s about energy sources and the power goes out, having a backup system that also runs on electric would not satisfy this but having a generator might.

If it’s about heat sources and my Steffes goes on the blink, then having another electric heat source would satisfy this.

If it’s about both, then the backup generator in combination with a backup heat source could cover both issues.

It’s my desire to not include propane in any of those scenarios, other than to run the outdoor generator.

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  1. Expert Member
    BILL WICHERS | | #1

    I’m not sure about any local requirements, but many insurance companies require a backup heat source for homes that are normally heated with wood or other fuels that require someone to tend the system. The insurance companies want a heat source that can run unattended. I’ve heard some stories from people who had similar issues with insurance requiring backup heat sources for heat pumps too, but I think that’s pretty unusual.

    Usually any conventional heat system that can run unattended will be acceptable as a backup system. This could be a boiler, oil or gas fired forced air furnace, or permanently installed electric resistance heat units.

    Note that in terms of system efficiency, you are much, much better off burning the propane directly instead of running a generator to make electricity and then using that electricity to make heat. That situation is worst for electric resistant heat, and sometimes when running heat pumps, depending on conditions. Sometimes economics dictates what you need to do though, since you’ll probably need to run the generator for backup electricity anyway, but there are propane heat systems available that do not require electricity to operate which can make them a good fit for backup heat situations.


  2. funkytut | | #2

    Thanks, Bill. I thought it might be a code thing, but the insurance angle makes a lot of sense.
    I agree with you about the losses in generating electricity and then using it to heat. It has occurred to me to run some sort of boiler outside the house in a heavily insulated shed and then pump hot glycol into the house via well insulated lines.

    There is some family history with propane that biases us against bringing it into the house, but most people have no issue with it.

    1. Expert Member
      BILL WICHERS | | #3

      You don't need glycol in lines that stay heated. Glycol is only needed in systems that may go below freezing. It's actually more efficient to move heat around with water alone, so don't use glycol unless you absolutely have to.

      You could potentially use propane to fire a boiler in an outdoor shed, then pipe the hot water circulation loop into the house. That would avoid propane going into the house, but still let you run a conventional system. You'll still need electricity for the circulation pump though, so you'll still need a generator, but at least you'll make more efficient use of your propane, which will save you money.


  3. paul_wiedefeld | | #4

    If you have an existing boiler, why not just keep it as backup? Cheap peace of mind there.

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