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  1. #1
    Join Date
    May 2011
    Location
    Tampa, FL
    Posts
    3

    New construction - HVAC options


    I seem to get different recommendations from everyone I ask. I'd like to get more feedback to see if any particular recommendations start piling up. Thanks in advance!!!

    Tampa, FL - south facing; 2,700sf (1,300 1st flr & 1,400 2nd flr); 2-story; open cell foam in attic; no load calcs yet; builder uses Carrier

    General thought is to go with a single unit, zoned for 1st and 2nd floors, The idea of going with a single HP unit to save on second unit and apply toward whole house filtration. I've heard a large single unit will be less efficient due to pulling larger loads when cycling. I like the idea of a single system to pair with a single filtration system. Zoning will allow me to raise the upstair temps during the day when everyone's gone (I work in 1st flr office)

    The builder's standard is a comfort/base system with an XL13 motor (I think that's what he said). I noticed Carrier's website says the comfort/base systems can achieve a 16 SEER rating. It also says the performance/comfort and infinity/performance models achieve a similar SEER (16-17). This is probably a newb question, but why go with a supposedly better system if the SEER rating don't increase.

    I definitely want a variable speed handler to address humidity. Will going this route allow me to skip the dedicated dehumidifier? The builder stated these can be loud ... I have no clue.

    Would going with a 2-stage compressor result in even better humidification? The builder stated I would see a return on the added cost around the 10yr mark ... any validity to this?

    Is there any validity to going with a straight AC system with heat strips or furnace (I'll have natural gas)? A buddy of mine (partner in a commercial engineering firm) feels heat pumps aren't needed in FL. I've heard HP units are much more efficient than straight AC units due to the high cost of heat strips. Even so, I probably only run the heat maybe 3-4 weeks out of the year. Is there much more involved in HP functionality that would add maintenance and repair?

    As you can see, I'm somewhat all over the place ... touching all aspects and trying to figure out which way to go. Not to discuss specific costs, but if a comfort/base system costs X, would a performance/comfort system cost 2X, a infinity/performance system cost 3X and infinity system cost 4X?

    Many thanks for any insight!!!

  2. #2
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,183
    go heat pump. strips suck.

    you'll probably have more repairs on the heat pump, but thats only because your not repairing something else heating your house.

    2 stage gives better dehumidification.

    if you using foam, you'll probably need outdoor air inlet.

    Teddybear will tell you that you need a dehumidifer, not just using the ac.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  3. #3
    Join Date
    Aug 2011
    Location
    Eastern South Dakota
    Posts
    28
    definatley heat pump, variable speed blower, 2-stage compressor, and the infinity control should be all you need there. with the foam insulation you definatley want a source of fresh air either through an ERV or a simple fresh air inlet if your climate allows it. as for the seer rating when it comes to heat pumps the HSPF and EER would be more important for heating.

  4. #4
    Join Date
    May 2011
    Location
    Tampa, FL
    Posts
    3
    Thanks guys! Before now, no one has suggested any fresh air processing. Does this simply entail connecting an air inlet to the handler? (I'll do more research on this as well.) Wouldn't this negatively effect humidity? I guess I would just adjust the humidistat to offset things?

  5. #5
    Join Date
    Aug 2011
    Location
    Eastern South Dakota
    Posts
    28
    I am from the far north so for fresh air we have to use ERV(energy recovery ventilator) or HRV(heat recovery ventilator) which will allow you to set how often and how much fresh air you need to cycle. depending on air temperature they will also help pull the humidity out of the incoming air before it enters your ducting system.

  6. #6
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    An ERV will exchange the air and recover some of the energy lost. The best way ot install it, I think, is to duct it so that it drawns stinkys air out of bathrooms and kitchen areas and ducts the fresh air into the air handler. many are 2 speed, so it rusn constantly and takes the place of the regular bath fans, but the air handler can increase the speed for additonal fresh air requirements.


    Go with a heat pump. If you can afford it, install 2 systems. With all that insulation I'd be suprised in either unit needs to be bigger than 2 tons if you go 2 stage.

    Sctually it might be so well insulated that you could use a single 3 ton 2 stage unit and zone the upstairs and downstairs into 2-5 zones.

    But only a load calculation can tell you that. The load calculation will also tell the installer what size ductwork is needed ot evenly cool every room.

  7. #7
    Join Date
    May 2011
    Location
    Tampa, FL
    Posts
    3
    Hmm, i like the idea of continually exhausting the bathroom and kitchen air. This sounds like it might add a good load on elec though.

    Im hoping a single 2-stage with zoning will be a reality. This means i don't need to get a filtration system for two head pumps.

    Anyone have a take on going with a comfort, performance or infinity model line? Why go the infinity route if a lower model can get you within 1 or so seer points.

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