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AC BTU Sizing question

branimal
branimal Member Posts: 259
in A-C, Heat Pumps & Refrigeration

I have a question on BTU sizing for a PTAC unit I'm replacing. The room is 20'x10' with 10' ceilings. It's a master bedroom. There is a hallway and a bathroom adjacent to this bedroom that have no HVAC (its nyc). So maybe my tenants turn on the AC and leave the doors open to cool the place. IDK. I know there is a home office setup by the entrance door. The other bedroom also has a PTAC in it.

The windows are very large, but there isn't a lot of sunlight b/c of another building blocking it. And there are window treatments to block the light.

I'm guessing if it was just the bedroom that was being cooled, 6k BTU would suffice. Maybe you bump it up to 9k b/c of the hallway and bathroom.

The smallest PTAC replacement unit is 9K (they don't make a 6k), but the wait time is 4-6 weeks.

There is a 12k in stock but I think it might be oversized. I'd get issues with short cycling and humidity removal based on a google search.

There is no visible plate with the model # or BTU rating of the old unit. Even with the cover off, I can't find an identifying mark.

What would you guys do in this situation?

(Heat is provided via hydronic pipes which run above the PTAC. The PTACS fan blows on the hot copper pipes).

rough sketch floorplan 2nd floor.png

Comments

  • pecmsg
    pecmsg Member Posts: 6,418

    units above, below, left, right?

    Another reason for an inverter system.

  • mattmia2
    mattmia2 Member Posts: 13,943

    The compressor ratings plate may give you sone idea of the size.

    The 1 ton would be way oversized no matter how you look at it, my 800 ft^2 house in michigan is probably 1.5-2 tons. The hallway adds some load but unless you have a fan to circulate air between the 2, don't count on it adding much load. Even the 9,000 btu/hr will short cycle in that space but will probably be manageable.

    branimal
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 18,426

    As @mattmia2 said get the amps and model/ serial # off the compressor. If the nameplate is missing or can't be read take an amp reading on that unit or one of the same size. Ilandaire should be able to help you determine the size.

    9k is probably more than you need

    branimal
  • Kaos
    Kaos Member Posts: 698

    They are not cheap but these are nice units. These are modulating units and have some turndown.

    Bonus these can also do full heat in most places so tenant pays for all utilities.

    https://www.ice-air.com/product/rsxc/

    8RSXC09

  • branimal
    branimal Member Posts: 259

    Thanks guys - I appreciate the help as always!!!

    Heat pump doesn't make sense b/c of the way the condo is piped…

    There's one large boiler in the basement that heats the copper pipes. It is shared for all the units. So the condo gets a bill from the utility and it is split up based on the square footage of each unit. It works the same way for cooking gas.

    So if I install a heat pump, my tenant will have an increased electrical cost. And they will effectively also pay for the gas bill without receiving the benefits in full.

    Not an ideal setup, but it is what it is.

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