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Boiler as backup for H/P

Dale Member Posts: 1,317
The answer is mixed at best and depends on what the heat pump can do now,and how the friend is satisfied with it. If a backup is needed and the elect resistance isn't enough then a boiler will surely work but seems overkill unless the system is set up to run the HP to 35 degree outdoor temp and then bring on the condensing boiler. If only a backup is needed then an instaneous water heater rated for space heating should be considered IMHO.


  • Dirk Wright
    Dirk Wright Member Posts: 142
    Hydro-air backup for H/P?

    A friend of mine wants to use his existing hydro-air system as backup heat for a new H/P. I have doubts that this will work, since leaving the boiler off for long periods is not good, or so I've read, but I don't have any experience with hydro-air. Anyone?
  • Joe Brix
    Joe Brix Member Posts: 626
    Depending on the climate

    The Hydro should probably be on whenever temps fall below freezing, especially with a coil in the attic. If the hydro uses high temp water, I don't see any condensation issues.
    Does the boiler also heat an indirect or other zones?

    Unless the house and duct system are very energy efficent, I doubt anyone would prefer the cooler temps of a HP once the temps get below 40°.
  • Dirk Wright
    Dirk Wright Member Posts: 142
    Forgot some data, sorry.

    He's thinking of a dual fuel arrangement where the H/P is shut off when it's 40 deg outside. The boiler only heats two hydro air zones, nothing else. He lives in Virginia. Wouldn't there be a significant delay if, during a heating cycle, the thermostat decides the H/P isn't up to the task and calls for hydro air heat? I would think that there'd be a long delay with the boiler coming on from a cold start. I also thought that it'd be tough on the boiler.
    thanks for your help!
  • Dirk Wright
    Dirk Wright Member Posts: 142
    I got them confused

    Sorry, I got backup confused with dual fuel. He wants a dual fuel system, where the boiler comes on when the outside temp dips below 40 deg. Thanks for your help.
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