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  1. #1
    Join Date
    Jul 2005
    Posts
    64
    I'd like to extend the ductwork to include the sunroom. It's a framed 3-season room with 12" of insulation in the roof, insulation in the floor and the walls are windows from the cieling down to about 18" from the floor.

    Can you do a residential Manual-J calc with that amount of window area? Or do you need to do a commercial calc? If I get the load calc software advertised in the top right of this page, then will it be able to calc the sunroom?

    The last HVAC guy to look at my system said it was 'Bordering on oversized' but he didn't do a load calc so I don't know who he could tell that. He also said that extending to the sunroom would be fine - but again, with no load calc I don't know how he can be sure.

  2. #2
    Join Date
    Sep 2004
    Posts
    3,157
    the walls are windows from the cieling down to about 18" from the floor.

    you would like to cool a room that is all glass. will this room be facing south? will it be covered by trees and shaded during the sunlit hours of the day? will it be totally exposed to the arizona sun and heat?

    instead of being borderline oversized, you may need to hope your system is severly oversized


    If I get the load calc software advertised in the top right of this page, then will it be able to calc the sunroom?

    the load calc will be able to calculcate anything that you have

  3. #3
    Join Date
    Jul 2005
    Posts
    64
    This is in Central Ohio. The sunroom is on the west wall of the house and has 3 glass sides, north west and south. The south windows are shaded by a roof overhang, and the north windows do not get direct sun.

    The west wall is about 20' long and is all glass. It gets direct sun from 1pm onwards. I was planning to have either a Sunsetter Awning or some Gila Platinum heat control film installed to reduce the sun load.

    Peak summer temps ate 95-ish for a couple weeks, and stay in the 80s the rest ofr the summer. The house has 2100sqft and the sunroom would add 200sqft to that. The system is a 3.5 ton and the HVAC guy said I could get away with a 3 ton (without looking at the ducts, house, windows etc.. )

    I'll get the software and do the calc.

  4. #4
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,964
    you're just asking to be disappointed. No matter what you do, the heat gain and heat loss of that area is going to always be different then the rest of the house.

    Your best bet is to have a ductless mini-split system installed.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  5. #5
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    What you wnt can be done with zoning,doubt your existing will handle it.

    If the do a load calc to see,it needs to include that room,meaning don't just load the room and /or the home separatly ,as the wall inbetween will be an interior wall ,when you do the two together.

    I go with what Robo suggested,then when it''s not in use,you don't need to condition it.The Fujitsu Brand is nowavailable in 13 SEER and R410a/Puron.

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