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Replacement ceiling diffuser for heat pump

wlee
wlee Member Posts: 22
edited September 25 in A-C, Heat Pumps & Refrigeration

I'm thinking about replacing a central air system with a ducted heat pump. The existing A/C system has ducts in the attic (which I plan on re-using for the HP) and diffusers in the ceiling. There is a single return in the ceiling in a common hallway. The diffusers are very similar to the attached image. These work fine for A/C in the summer, but I am concerned they won't be as effective for heating. Is there some kind of hybrid diffuser with the same footprint I can look at that would serve both cooling and heating? I'd prefer to re-use the existing ceiling holes and not cut new ones if I don't have to. This is for a home in the Hudson Valley of New York state. Existing heat is hydronic with an oil-fired boiler, which I still intend to use on colder winter days. Thanks.

diffuser.jpg

Comments

  • Kaos
    Kaos Member Posts: 726

    The existing diffuser type doesn't matter, what you want is the duct size behind it.

    With ceiling register and for heat to work well you want something with decent throw straight down, you have to get the air down to floor level to mix. You also have to watch where people will sit as you don't want to blow air directly at people.

    I used regular adjustable commercial grills from our local supply house, something close to this:

    https://www.hvacquick.com/catalog_files/Dayus_dahd_Cut_Sheet.pdf

    Important bit when doing this type of hvac work is to get a duct blaster test and make sure the new install is reasonably air tight. Air leaks in attic mounted units can be a big source of heat loss, around the neighborhood of 25% is common, a bit of air sealing now has a big return on operating cost.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 18,555

    Overhead heat especially with a lo temp heat pump will not work well when it is cold. It might be ok in the spring and fall.

  • HVACNUT
    HVACNUT Member Posts: 7,001

    If the diffuser shown is what you have, then its more than just a diffuser replacement. What you're showing comes as a combination register/boot so replacing the diffusers will also need new boots.

  • Kaos
    Kaos Member Posts: 726
    https://forum.heatinghelp.com/discussion/comment/1865936#Comment_1865936

    That was definitely the case with older single speed heat pumps. Newer cold climate units deliver rated capacity down to 0F is some cases, that means the supply temperature does not drop even when cold. I have a cold climate unit up at the cottage where -15F is common and the air coming out of the unit is well above 100F even on the coldest nights.

    Speaking of which, @wlee make sure they install a unit with vapor injection (hyper heat, cold climate etc.).

  • wlee
    wlee Member Posts: 22
    https://forum.heatinghelp.com/discussion/comment/1866042#Comment_1866042

    I'm not familiar with vapor injection, can you expand on it a bit? Is it a feature unique to a particular brand?

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