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  1. #1

    Considering Cooling Upgrade for In Wall Units

    I am buying a home in the Philadelphia suburbs that was constructed in the 20's. There is no original duct work in the home, it has radiator heat (which I like), and in-wall AC units in some of the rooms with condensers outside. Not every room is cooled though, which I expect will be problematic in the summer.

    The units are ugly as sin in the interior of the home, but do not show, thankfully, through the wall on the outside. The home is registered as "central air" in the municipal records, but I always understood central air to be a traditional duct cooling system. I have not been able to find info on these wall units online that explains the installation methods - can someone help reconcile the use of the term "central ac" with these units?

    Can these types of units be replaced with more modern/sleeker looking units, depending on fit? (See pic)

    What would be the first step towards determining whether traditional system or high velocity would be suitable for the home? I do not have any storage space on the third floor finished attic - is storage a requirement for either system type?

    Thanks for your help.
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  2. #2
    Join Date
    Jul 2004
    It appears you have some very early model mini-split ductless units in your home. Yes, they can easily be replaced by more up to date units. There are several manufacturers but among the most popular are the Mr. Slim line of products.

    As far as a true ducted, central system is concerned, you'll need to find a company that does room-by-room load analysis before quoting on the job. You can find companies all day that don't do load analysis but rather just guess, even though they may claim to do load analysis. A true analysis will produce documents to substantiate the sizing of the system.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  3. #3
    Join Date
    Feb 2010
    NE Alabama
    Each public entity can use any number of definitions to describe various systems. You need to delve into the code book for Philly to understand if your system was correctly described.

  4. #4
    Thanks for the replies everyone. So I'm working with older mini-splits in the living room, kitchen, dining room, master bed, and third floor bed.

    That leaves no cooling in 2 bedrooms, an office, and a sun room (and the sunroom doesn't have a free "wall" to put in a new minisplit due to three walls of windows) as well as three bathrooms, hallways, etc.

    With this many rooms left to cool, and no ductwork in the home:

    - Which do you think would be the best type of system to go with - additional multi-zone minisplits, high velocity tubing, or a traditional HVAC duct system? I have a feeling if I call an HVAC guy I'm going to get an HVAC recommendation, high velocity guy, an HV recommendation, etc.

    - Which choice would be more economical (can you ballpark the pricing of running ductwork and hvac without violating board's pricing policy?)

    - Quieter (are HV systems really loud?), efficient in terms of energy use, etc.

    - Where does the ductwork go in a house with plaster walls and no existing ductwork?

    The house is a three story colonial, approx 2100 sq ft, I have 200 amp service.

    Also, regarding the existing minisplits - If I pull an older model off the wall, will a new model fit the old spot, with the same hookup tubing, and the old condensers, or do all the components have to be replaced?

  5. #5
    Well good news is I've moved into the home and the units do a pretty good job cooling the rooms we use most. The other beds are doing fine with window units.

    One major problem is that the previous owners were big time smokers and the unit in the kitchen reeks of cigarettes even after we took it apart and cleaned it. I spoke with a Sila contractor today, and they said it will cost $4k+ to replace each unit. Not in the budget.

    The model I want to replace is a Mitsubishi MS-09DW-U1 evaporating unit, runs on R-22 coolant. Any advice on whether I can retain the existing line-sets and outdoor exchanger, and just replace the evaporating unit? Can anyone recommend a reliable contractor, online seller, and/or replacement unit?

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