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Boiler zone with baseboard and air handler?

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drosner
drosner Member Posts: 45
My AC unit feeds an air handler that also gets a feed from my boiler for ducted air that cools/warms my kitchen. The AC unit and air handler are 15+ years old and finally gave out. I'm replacing those and before i do the install i'm wondering if having the air handler on the same zone as other baseboards is the right thing. I've got 8 zones for my whole house and this 1 zone feeds 2 baseboards and then the air handler in one run supported by 1 circ pump.

Is this ok to have a single zone controller by a single t-stat that has a pump and feeds multiple baseboards and then a heat exchanger within the air handler?

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  • Jamie Hall
    Jamie Hall Member Posts: 23,426
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    Did the old setup work? Was the space comfortable that way? If it ain't broke, don't fix it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,611
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    @drosner
    In a perfect world I would put the AHU on a seperate zone. But if the baseboards are in the kitchen and and it worked ok before I would leave it as is
  • HVACNUT
    HVACNUT Member Posts: 5,861
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    I would feed the baseboard first and give the coil the leftovers.
    Do you know which way its piped now?
  • mattmia2
    mattmia2 Member Posts: 9,735
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    If the baseboards need to run longer, you could always control the air handler to shut down the blower when that part of the zone is satisfied.
  • HVACNUT
    HVACNUT Member Posts: 5,861
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    > @mattmia2 said:
    > If the baseboards need to run longer, you could always control the air handler to shut down the blower when that part of the zone is satisfied.


    That would take an additional thermostat (kitchen) and a parallel/series circuit to interrupt the blower while continuing to run on the BB thermostat. Just zone it at that point.
  • mattmia2
    mattmia2 Member Posts: 9,735
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    HVACNUT said:

    > @mattmia2 said:

    > If the baseboards need to run longer, you could always control the air handler to shut down the blower when that part of the zone is satisfied.





    That would take an additional thermostat (kitchen) and a parallel/series circuit to interrupt the blower while continuing to run on the BB thermostat. Just zone it at that point.

    Zoning would require some amount of re-piping and a zone valve. The thermostat to shut down the air handler would require a thermostat and some wiring and maybe a relay in the control circuit to the blower but since it already handles AC it is likely already has a low voltage control.

    I suspect that this zone is relatively small and one or the other overheating before the other is satisfied isn't an issue, it is just there because they couldn't get enough radiation in the kitchen for that zone so they are all heating more or less the same area.
  • drosner
    drosner Member Posts: 45
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    Appreciate the comments and help. When I first moved in i had a thermostat for the baseboard and one for the air handler. I never understood why since they are on the same circuit. When they put the new air handler in they didn’t have a small pump like the old one but then decided it wasn’t needed. To save from the Extra plumbing they just stuck the AH on the existing circuit and gave it its own tstat. The small pump inside the handler was good enough. My kitchen that gets the forced air never was warm enough on cold days because the furnace wasn’t firing even when the AH was on. So I just wired that zone to 1 tstat for baseboard and AH.

    As you have all said...if it works then it works. The AH is at the end of the run btw. Not sure if that will matter but we will have to wait for the winter!
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,044
    edited June 2020
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    Your last post indicates that something needs to be fixed. So that does not qualify for “ if it ain’t broke…”

    How easy would it be to use O2 barrier PEX tubing to make a Home run back to the boiler with a small circ pump, relay, and thermostat? I don’t think that many Wallies like two different emitter types on one zone or loop. Any other thoughts?

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,044
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    Does the air handler air-conditioned the entire home? To be more specific; are all eight heating zones air-conditioned buy that air handler?

    If the answer is yes, then this will not solve the problem of a cooler kitchen in the winter. To solve the cold winter kitchen problem, you might think about adding a under counter hydronic heater.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    mattmia2
  • mattmia2
    mattmia2 Member Posts: 9,735
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    Does the air handler air-conditioned the entire home? To be more specific; are all eight heating zones air-conditioned buy that air handler?



    If the answer is yes, then this will not solve the problem of a cooler kitchen in the winter. To solve the cold winter kitchen problem, you might think about adding a under counter hydronic heater.

    That was the part that was confusing me as well. If the air handler is heating all zones, it would be very difficult to make it all balance.