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  1. #1
    Join Date
    May 2004
    Posts
    22
    While waiting for my Carrier guy to get back to me - something stalled - I got a bid from an Amana installer - he is recommending 4 ton (14 SEER RCE Prestige & 80% AMV8 Furnace) whereas everyone else (Carrier, York) has said 3.5 ton.
    When asked why 4 ton when others recommend 3.5 his reply was, “we always use the 4 ton for 1600 sq ft. - (4 x 400) and you are almost 1600 - plus it’s only $50 bucks more - so why not?”
    My current never did a *great* job rig is 3 ton (installed when 1987 1500 sq ft tract house was built). FWIW, Amana guy would pull the current 40 amp and put in a 50 amp breaker.
    So here is the Big Q:
    Will 1/2 ton one way or another pose any significant problem - eg, too fast/slow cooling, inappropriate cycling, etc?


  2. #2
    Join Date
    Feb 2002
    Location
    Houston Tx
    Posts
    344
    Will 1/2 ton one way or another pose any significant problem - eg, too fast/slow cooling, inappropriate cycling, etc?

    You answered your own question, But why 400 sq ft a ton come from ? thats very old school and you need another HVAC quote....

  3. #3
    Join Date
    Aug 2003
    Posts
    502
    1600 SQ FT,4-ton,where are you located the amana dealers a/c and electrical knowledge sounds scary did he verify wire size for the 50 amp breaker?

  4. #4
    Join Date
    Jul 2002
    Location
    Zelienople, Pa
    Posts
    2,965
    Only buy from someone doing a Manual J load calculation.

    Rules of thumb = mold!
    How tall are you Private???!!!!

  5. #5
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    First as stated above,a Manual J ,from ACCA ,load clculation is needed.You can use HVSC-Calc,on this site ,and do it yourself for a very low cost.

    There could be a lot of reasons that the 3 ton didn't cool well ,other then being too small.

    A larger system needs larger ducts to work properly and deliver ALL the tons you are paying for.Larger system,not work very likely needs to done.

    After the load calculation,rerun it with upgraded attic insulation,meaning if you have R11 in the attic,run it as R30,and see if it reduces your tonnage ,by a 1/2 ton.In Florida ,that's what would happen on > then 1500 sq. ft. home.

    Reducing the tonnage needed gives you major saving ,forever.You can also see the reduction in size,by adding tint to your east and west facing glass .

  6. #6
    Join Date
    May 2002
    Location
    Colorado
    Posts
    697
    Dash is right on.

    You say in your other post that you live in the high, dry California desert. How high? It makes a difference in the required air flow.

    If you are at 5,500 feet like I am, you need around 650 to 700 CFM per ton in order to get the temperature of the air leaving the indoor coil up to 58 °F or thereabouts. If you can't get that much air flow through your ducts, your system won't put out it's rated tonnage and will be inefficient. This fact is not understood by 99% of the pros who design, install, or service HVAC systems in high desert climates.

    Chances are excellent your present system does not have a TXV, is improperly charged, and has low air flow. A good 3-ton system should be able freeze you out of your house.

    If you follow Dash's advice and also tighten up air leaks in your home, you probably can stay very cool all summer with a 2-ton system. Of course it has to be properly installed. Think how much that will save you now and each summer? Do it right and start with a Manual J calculation.




  7. #7
    Join Date
    May 2004
    Posts
    22
    Thanks to all - again. We're at 2500' above sea level. I'm slowly getting the drift here - sure wish one of these guys would run a manual J without being cattle prodded - my Carrier guy finally got back to me - will call him again on Monday - and bring up the Manual J calculation - fwiw, he sent over a quote for the Performance 14 and a Comfort 80 Furnace/Blower (3 ton!).
    Sure appreciate you guys taking the time to help me through this...
    Few new windows and getting some more insulation blown in the attic will be the next move....


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