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Insulation and AC opinions requested

JSDNJ
JSDNJ Member Posts: 19
in THE MAIN WALL
Hello,

I am revisiting an old topic a bit, but I have updated my information to be a little more comprehensive and hopefully easy to understand.

I live in a 1 1/2 story home that's about 1350sf, in New Jersey. I have a 2 ton central air unit with an insulated air handler and insulated ducts in the attic. As it stands, the current unit struggles to cool the upstairs on a hot day in the summer, and it's 'ok' but not great downstairs. When the sun begins to go down it cools just fine, and on normal days its decent but not great. The delta T is acceptable generally and I had the unit checked out. It's working normally.

I am enclosing a screened in porch with knee walls and windows and adding heat/air to that space. This will make my overall sf about 1450. The porch is only 100 sf, but we want it to be comfortable, so in researching how to achieve this I thought it would be a good opportunity to address the rest of the house as well, by way of insulation or mini splits or both. The insulation we currently have in the master is R13 on the sidewalls and some older thicker stuff on the attic floor under some plywood. The images go over 3 options I have gathered from various research and opinions of HVAC pros, but I am at a loss as to which way to go. Any and all opinions are greatly appreciated as this has had my head spinning for a while now.

https://i.imgur.com/iXT0ci8.jpg

https://i.imgur.com/8CuUPY6.jpg

https://i.imgur.com/GaG1p1p.jpg


Comments

  • hvacfreak2
    hvacfreak2 Member Posts: 500
    Option 4 - Wreck out existing ahu and associated equipment . Select a single phase VRF system such as a Mitsubishi S Series ( or M series with hyper heat ) including new ahu for existing spaces , master b.r. , and porch area.
    hvacfreak

    Mechanical Enthusiast

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

    Easyio FG20 Controller

  • JSDNJ
    JSDNJ Member Posts: 19
    hvacfreak2 said:

    Option 4 - Wreck out existing ahu and associated equipment . Select a single phase VRF system such as a Mitsubishi S Series ( or M series with hyper heat ) including new ahu for existing spaces , master b.r. , and porch area.

    Well I'm not sure what that is but it sounds like more money than I want to spend. Any comment on the insulation?
  • hvacfreak2
    hvacfreak2 Member Posts: 500
    edited December 2017
    Well , you are looking at adding a new system anyway as well as paying to re-route duct , etc.

    Residential insulation is something I don't know enough about to comment on. I have seen a nicely done spray foam job that I was impressed with. It was a walk-up attic ( older structure ) and they foamed the roof sheathing and the rafters. It was a hot sunny day and the attic stayed cool throughout the day.
    hvacfreak

    Mechanical Enthusiast

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

    Easyio FG20 Controller

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,599
    Hello, I like #3 as it seems to be the only one where you're improving the shell. I'll add that it's best to use a blower door to find and seal air leaks, FIRST, then insulate. A question, do you have a dark roof? This can add a lot to your cooling load!

    Yours, Larry
    Canucker
  • JSDNJ
    JSDNJ Member Posts: 19
    hvacfreak2 said:

    Well , you are looking at adding a new system anyway as well as paying to re-route duct , etc.

    Residential insulation is something I don't know enough about to comment on. I have seen a nicely done spray foam job that I was impressed with. It was a walk-up attic ( older structure ) and they foamed the roof sheathing and the rafters. It was a hot sunny day and the attic stayed cool throughout the day.

    True, but removing the newish existing system would seem even more costly. Is the system you're suggesting one with multiple mini splits?
  • JSDNJ
    JSDNJ Member Posts: 19
    Larry Weingarten said:

    Hello, I like #3 as it seems to be the only one where you're improving the shell. I'll add that it's best to use a blower door to find and seal air leaks, FIRST, then insulate. A question, do you have a dark roof? This can add a lot to your cooling load!

    Yours, Larry

    The roof is actually a lighter brown color. In option 3, doesnt that increase the area needing to be conditioned?
  • hvacfreak2
    hvacfreak2 Member Posts: 500
    Yes , multi " head " ( indoor units ). I know two people ( industry pro's ) with M Series Hyperheat systems and they are very happy with them. Equipment cost wise it seems like a lot of " bang for the buck " when compared to some standard high efficiency systems. The M Series also has an MNET adaptor that can allow the use of the commercial central controllers , and probably some other add-ons that I am out of the loop on. I have assisted with a few S-Series VRF systems in houses but I have not heard any feedback.
    hvacfreak

    Mechanical Enthusiast

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

    Easyio FG20 Controller

  • JSDNJ
    JSDNJ Member Posts: 19
    hvacfreak2 said:

    Yes , multi " head " ( indoor units ). I know two people ( industry pro's ) with M Series Hyperheat systems and they are very happy with them. Equipment cost wise it seems like a lot of " bang for the buck " when compared to some standard high efficiency systems. The M Series also has an MNET adaptor that can allow the use of the commercial central controllers , and probably some other add-ons that I am out of the loop on. I have assisted with a few S-Series VRF systems in houses but I have not heard any feedback.

    My brother in law just did one of these. I think if I had no existing system it would be an option, but I dont have a very open floor plan and I'd need a head for each bedroom (probably need 5 or 6 heads total) which would be pretty expensive. The existing central air was installed in 2015.
  • hvacfreak2
    hvacfreak2 Member Posts: 500
    edited December 2017
    They have ducted air handling units that work with these. You can have a combination of ducted and ductless units on the same system.

    mitsubishicomfort.com/products/renovation#products
    hvacfreak

    Mechanical Enthusiast

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

    Easyio FG20 Controller

  • JSDNJ
    JSDNJ Member Posts: 19
    hvacfreak2 said:

    They have ducted air handling units that work with these. You can have a combination of ducted and ductless units on the same system.

    mitsubishicomfort.com/products/renovation#products

    Totally, I just can't justify ripping out a 2 year old split system at this point.
  • ratio
    ratio Member Posts: 3,791
    If you're considering a VRF system (anyones), note that unless you have a BDU/branch box/whatever-they-call-it, the heads will only operate in the mode selected by the outdoor unit; i.e. heating mode or cooling mode. Some systems even distinguish fan-only as a 'mode' and one head out of agreement parks the system. Others merely park that particular head until the system changes mode. On the two systems I've installed, it took a central controller of some type to do any kind of intelligent auto changeover, making the system as a whole even more expensive!

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