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2 Room addition of 700-800 sq ft

Currently I am in the process of enclosing my existing 30x20 patio and extending the current living area along with adding an office space. My home is originally at 2175 sq ft with a 3 1/2 ton heat pump hvac system ten years old. Runs perfect some problems in the past but all repaired.
My question is what would be the best option for my addition. It would obvisouly require two new ducts in living area and one in the office space. Do I upgrade system to newer models if so how much more do I require and which system. Or I here there are new more practical systems "mini split ". What are the pros and cons and of course price difference? Thanks in advance

Comments

  • JUGHNEJUGHNE Member Posts: 6,201
    It all depends upon where you live....weather wise.
  • notsohandynotsohandy Member Posts: 3
    San Antonio Texas. Believe it's of the hotter zones of the US
  • ChrisJChrisJ Member Posts: 10,239
    How does the system behave now?
    As in does it barely keep up all the time or does it seem like it has plenty to spare?

    If it struggles to do what you want now, it certainly won't handle another 800sqft.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • njtommynjtommy Member Posts: 1,105
    I would say ductless mini split or a ducted mini split system. They are pretty small and can be mounted in a lot of different configurations.
  • JUGHNEJUGHNE Member Posts: 6,201
    Mini split heat pump/AC should do it there without backup heat.

    Assuming your ductwork is in the attic, that might consist of possibly overextended runs of small round duct back to the
    main plenum.

    I would consider a multi mini system with 1 inside unit for each room if the floor plan was friendly to that plan.
  • notsohandynotsohandy Member Posts: 3
    Excellent advice guys appreciate it. Current system works fine in cooling though with a lot of family it tends to struggle during holidays or cowboy games. Combo of body heat and the in and out opening of doors. But in general it cools just fine we keep it usually 74-75 degrees which is to most not even cold but is for us.

    These mini split systems do they require being mounted up high on ceiling or can they go down on lower end of an exterior wall. And being that I have a large room 14x18 being enclosed for additional living area space and then a 10x10 office being enclosed with one door entry in from home and an exterior door exiting to back yard would one mini split system come with two in home units tied into one condensing unit outside or would I require a larger unit for the bigger room and a second unit for the smaller room?

    Sorry I'm a registered nurse and clueless to all this. Just know that I go online and see multiple systems available but not sure past what I see. Had several guys come give options and bids from bigger companies locally and they want 10-14k which is insane I think.
  • njtommynjtommy Member Posts: 1,105
    They do have floor mount ones now here is a picture of one.

    They have ceiling mounted and wall mounted units to. The ceiling ones are nice, but make sure you let your framing contractor know cause they will need to make some adjustments to there framing.

    Yes you can have multiable indoor units with 1 outdoor unit with out any problems.
  • hvacfreak2hvacfreak2 Member Posts: 474
    edited October 2016
    We refer to them as " ductless " in the industry , but there are many DUCTED indoor units available within these product lines as well. Just so you ( op ) know.
    hvacfreak

    Mechanical Enthusiast

    Burnham MST 396 , 60 oz gauge , Tigerloop , Firomatic Check Valve , Mcdonnell Miller 67 lwco , Danfoss RA2k TRV's

    Easyio FG20 Controller

  • ChrisJChrisJ Member Posts: 10,239
    njtommy said:

    They do have floor mount ones now here is a picture of one.



    They have ceiling mounted and wall mounted units to. The ceiling ones are nice, but make sure you let your framing contractor know cause they will need to make some adjustments to there framing.



    Yes you can have multiable indoor units with 1 outdoor unit with out any problems.

    I can't believe you posted that second picture with a radiator removed.

    I'm speechless, and you do this to me on a Friday right before I fight with 287 again? With friends like you.......................... :)
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • FredFred Member Posts: 8,102
    Make sure you understand how those mini splits get cleaned/maintained annually. Everything I have heard, that is one of the trade offs between ducted and ductless systems. I'm sure others can/will elaborate.
  • njtommynjtommy Member Posts: 1,105
    Sorry @ChrisJ I didn't look close enough at the picture. I would of never done that on purpose. Lol.

    Yes good point Fred. Mini splits do need cleaning and with out clean regular cleaning they can develop mold on the blower wheels and on Supply air grill area . They do make UV lights now that go right inside the supply air grill. That will kill most of the mold problem.
  • JUGHNEJUGHNE Member Posts: 6,201
    Will your addition be on slab, that is you would have a concrete floor poured? Or do they do crawl spaces, giving you a wood floor? It would probably match what you have for the rest of the house.

    The most economical multi mini split would be wall hung units inside. They would be installed about the height of the top of your windows...a foot or so down from the ceiling. That robs no floor space. But you have to get used to looking at them.....not terrible.
    They can also be mounted on inside walls if needed.
    A small wall unit in the office and a larger one in the living space, preferably on the 14' wall for the air flow to hit all of that room.
    One outside unit could take care of both inside units.
    If you could provide a simple floor plan as it is to be connected your house. Just include walls, doors and windows.

    Just a private note/joke for ChrisJ: did you see the 74 to 75 degree comment, this is Texas!

  • ChrisJChrisJ Member Posts: 10,239
    JUGHNE said:

    Will your addition be on slab, that is you would have a concrete floor poured? Or do they do crawl spaces, giving you a wood floor? It would probably match what you have for the rest of the house.

    The most economical multi mini split would be wall hung units inside. They would be installed about the height of the top of your windows...a foot or so down from the ceiling. That robs no floor space. But you have to get used to looking at them.....not terrible.
    They can also be mounted on inside walls if needed.
    A small wall unit in the office and a larger one in the living space, preferably on the 14' wall for the air flow to hit all of that room.
    One outside unit could take care of both inside units.
    If you could provide a simple floor plan as it is to be connected your house. Just include walls, doors and windows.

    Just a private note/joke for ChrisJ: did you see the 74 to 75 degree comment, this is Texas!


    Yeah,
    But not sure what your point is?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
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