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Hot water baseboard to air

I am renovating my home and my contractor suggested that I convert me heating system. Right now i use a gas boiler to circulate hot water to baseboard heat. He proposes that the hot water be diverted to a coil in the attic where air will be heated and blown out through the existing air conditioner ducts. I really don't know the ramifications of this. One plus is that I will not have baseboards, but I am not sure if I like hot air blowing. Someone told me that the top floor will always be too hot. Does anyone have any opinions on this topic. Thank you in advance for your help


    JUGHNE Member Posts: 11,074
    If your AC is in the attic now, that system was designed to put out cool air with the second floor in mind as needing the most air applied to it. IMO
    Where are the return air inlets for the existing system....which floor?
    Is the attic heated.....would the boiler water be in danger of freezing?
    IIWM I would keep the BB heat as is. Quiet. In my case I have zone control for most areas with hydronic heating.
  • Jamie Hall
    Jamie Hall Member Posts: 23,415
    I can't say that I'm a fan of forced air heat -- having that breeze from time to time just doesn't appeal to me. The only advantage that I can see is that you wouldn't have the baseboards. You also wouldn't have the opportunity to zone the baseboards to get different levels of warmth in various places, unless your existing ductwork has outlets in all the spaces and dampers with thermostats for them. Your existing ductwork may or may not work well for heating; if there are adequate supply registers in all the rooms -- especially downstairs -- it might work.

    But... I wouldn't do it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Brewbeer
    Brewbeer Member Posts: 616
    It's generally considered bad form to put HVAC equipment in unconditioned spaces. Personally, I think HVAC blowers can be noisy. Baseboards, when coupled to the right boiler and installed correctly, provide comfortable, quiet and even heat without using electricity to blow a lot of air around the house.

    What is the rationale for ditching the baseboards in favor of the in attic air handler?
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread: http://forum.heatinghelp.com/discussion/154385
    System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg
  • John Mills_5
    John Mills_5 Member Posts: 952
    The downstairs will always be cold, you will not like that at all. As long as you have a boiler, you'd be lots better off using the baseboard. Like JUGHNE said, the ducts and outlets were designed for cooling. I have no issues with forced air but when it blows from above it can be lots less comfy.
  • jacobsond
    jacobsond Member Posts: 90
    Right now you have the best of both worlds. Nice even hydronic baseboard heating and a stand alone central air system. Why mess with that. The extra wall space you would gain by loosing the baseboards is not worth the likely discomfort with your heating system that your guy is proposing. I assume your contractor is not a heating pro.If you decide to go his route get a proper heat load done by a good heating pro. You may find that a coil in the air handler will not work for you.

    There was an error rendering this rich post.

  • Gordy
    Gordy Member Posts: 9,546
    You don't want the attic system for heating. In an unconditioned space your going to get a blast of cool air every time the heat calls until the ducts warm up. Then the warm air that's in the structure will migrate back up into the ceiling ducts between calls.

    AC is a bit different. As cold air falls so it does not migrate back up in the ductwork.

    You have AC now have you noticed in the summer while in use warm air blowing out at the start of a call for cooling?

    Noise is also a draw back.
  • hydro_newbie
    hydro_newbie Member Posts: 37
    Besides the other items mentioned here, there may be an economic factor as well.

    Heat is delivered to the rooms by pumping hot water via a circulator pump. With the coil system, the water will be pumped into the coil, but then the coil will then need a fan to run to warm and distribute the air. I'm not sure if it's fundamental, but I suspect it generally takes less electricity to move heat via a circulator pump than compared to the fan.

    At the least it may be worth finding out how much electricity the fan motor will consume when active. It may not seem like much, but if the boiler is correctly sized, and thus running for long stretches, it could add up. It'll depend on the motor efficiency of course.

    Note the username...hopefully some of the experts here will correct me if I'm off!
  • Gordy
    Gordy Member Posts: 9,546
    Agreed with hydro air you are running a circulator, and a fan. Verses one, or the other.
  • Leonard
    Leonard Member Posts: 903
    edited February 2017
    On a generator website I hear cellar forced air systems have ~ 1hp blower motor , my water circulator is ~ 0.08 hp motor. Extra starting amps of larger motor and blower inertia can up required gen kw rating to start the heating system during outages. Of course blower motor size will vary with size of air handler.

    1 hp = ~ 745 watts, here 1 KWH (1000 watt-hours) costs ~ 17 cents. From my yearly fuel consumption I estimate ~ 900 run hours/yr, large house , I figure extra $100/year if 1 hp

    I've got forced hot water baseboards, the cast iron 12 " high x 2 " thick with cast fins on back type that run the whole perimeter of house. VERY nice comfortable uniform heat. Sluggish to respond if you want to change thermostat day and night, but I don't.

    Friend with forced air, says she has to dust all the time.
  • Gordy
    Gordy Member Posts: 9,546
    edited February 2017
    Noisey too bad....the forced air.