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  1. #1
    Join Date
    Dec 2005
    Posts
    1
    In the market for a new heating/ac system. Had 2 sales guys come out to quote and each had a different opinion on what could be an effective solution for us. Another 2 coming later today.

    Here's our quick situation: 3000 sq ft single level home, L-shape flr plan w/ living space on 1 side of 'L' and BR's on other. BR's further away from furnace - MBR furthest - and getting very little heat. Ducts have been checked - no major leaks, combo of 12" (core runs) and 6" (fingers). Current unit is York - 17yrs old and described by all as 'junk'. We live in SF Bay Area hills (CA)- winter temps down to upper-20's, summer highs to upper 90's.

    1st guy: admitted his top rec was the best and most expensive, but suggested Carrier Infinity (58MVP120 + 38TDB060 + new coil + 2nd return) with 2-zones, 1 for living, 1 for sleeping areas. made sense given that we spend days in living space and night in BR's. but fairly expensive ($13k all-in, incl discounts).

    2nd guy: said 2 zone was a waste for single level and we could do just fine w/ single zone. he suggested trane xb-90 120,000btu + adding dedicated single run to MBR + add'l return + new a/c coil. a/c condenser still running, so keep it, but change coil to avoid re-installing furnace when coil goes. his price quote $7k.

    heard that zoning runs ~ $2.5k and a/c condenser $4k, so quotes seem comparable adjusting for add'l stuff. Tho Carrier unit is the more advanced 2-stage vs. trane unit - don't know how much $$'s that counts for.

    can anyone answer the 1 vs. 2 zone question for us? most threads on 2-zone have related to 2 story home and ours is single level. in reading threads i learned to appreciate that installation is more important than brand name, but would welcome sizing/efficiency recommendations from anyone.

    regards


  2. #2
    Join Date
    Jun 2005
    Location
    Near Chicago, IL
    Posts
    3,316
    Anyone done a load calc yet? Better get one- especially for the cooling part. I suspect that the cooling load on your home may exceed the capacity of a 60k btu unit.

    Why do zoning? Unless you have a two stage condenser and two stage furnace, you still operate the equipment at 100% and dump the rest somewhere.

    Inadequate airflow, especially at the furthest points on a system, is a sure sign of poor design or installation.

    If you piece a condenser/coil combo, better make sure that your coil will work with the 13 SEER stuff.

    Thought pricing wasn't supposed to be posted....
    Proper Prior Planning Prevents Piss Poor Performance

    "There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who consider price only are this man's lawful prey. It's unwise to pay too little.
    When you pay too much, you lose a little money -- that is all. When you pay too little, you may lose everything, because the thing you bought was incapable of doing the thing it was bought to do.

    The common law of business balance prohibits paying a little and getting a lot -- it can't be done. If you deal with the lowest bidder, it is well to add something for the risk you run. And if you do that, you will have enough to pay for something better."

    John Ruskin


  3. #3
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,642
    house that large and living spaces split up the way they are zoning would be a good idea. either 2 stage units with zoning system or split of ductwork completely and do 2 smaller systems

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