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  1. #1
    Join Date
    Oct 2005
    Posts
    2
    I'm working with a Trane dealer with a strong reputation and long track record to replace my old 2 heat pump system. The current system has two 2.5 ton 'split' units (remote air handlers) upstairs/downstairs. The initial proposal he and 2 other dealers put together called for a direct replacement two 2.5 ton Trane XL14i (14 SEER and 8.5HSPF) heat pumps and matching variable speed air handlers.
    The dealer came out today to perform load calculations and take some final measurements. He is now suggesting a pair of 2 ton XL16is mated to the same variable speed air handlers for roughly the same as the 2.5 ton XL14s.

    I like the idea of greater energy efficiency but am concerned that the 2 ton units won't keep up on HOT Sacramento afternoons. The XL16 has a variable speed compressor, I'm concerned that I'll lose any energy savings of moving from 14 to 16 SEER by running it on 'high' all the time.

    I'd appreciate any thoughts, questions or discussion points for my next meeting with this contractor




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  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,916
    Obviously a 16 SEER costs a bit less to operate than a 14 SEER. The SEER is for high operation so don't worry about that. What does the house need? If it needs 2 ton, go for the 16. If it needs 2.5 ton, either go the 14 or the 3 ton 16. The XL16i has a single speed compressor with an unloader to make it 67% efficient on first stage.

  3. #3
    Join Date
    Mar 2004
    Posts
    1,042
    Originally posted by BaldLoonie
    Obviously a 16 SEER costs a bit less to operate than a 14 SEER. The SEER is for high operation so don't worry about that. What does the house need? If it needs 2 ton, go for the 16. If it needs 2.5 ton, either go the 14 or the 3 ton 16. The XL16i has a single speed compressor with an unloader to make it 67% efficient on first stage.
    I'm pretty sure he means that the XL16i runs at 67% capacity on first stage. The efficiency is slightly higher on first stage than on second stage

  4. #4
    Join Date
    Oct 2005
    Posts
    2

    Load Calc

    I just sat down with the contractor and reviewed the load calcs. he indicates the (given a outdoor temp of 105 and desired indoor temp of 75) the required cooling BTU is 21291 for the upstairs and 23552 for downstairs. Heating BTUs required (assuming 32 outside and 70 inside) are 21066 up and 20008 downstairs.

    He is recommending a 2 ton XL16i (4TWX6024) and variable speed air handler (4TEE3F31A) upstairs and a 3 ton XL16i (4TWX6036A) and variable speed air handler (4TEE3F40A).
    Both units have supplemental heat strips (BAYHTR1405).

    This set up is reputed to be very efficient:
    Upstairs 16 SEER, 12.6EER and 8.65HSPF
    Downstairs 17SEER 12.7EER and 10.55HSPF

    Due to efficiency rebates from my local utility, the price is remarkably close to the two 2.5 ton XL14i system previously quoted which was markedly less efficient.
    which was 14SEER, 12.1EER, and 8.5HSPF.

    Given these load calcs, I'd love some input on the sizing
    as well as your thoughts on the proposed system.

    Thanks

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,916
    Why do a heat gain and ignore it? Last thing I'd do is put the big unit downstairs. Someone needs to tell him heat rises. Heat that infiltrates downstairs will go up. Cool air put out by the upstairs system will fall downstairs. If the calc calls for 20,008 down, you sure don't need to oversize by 80%! With those figures, makes sense for 2 units 2 ton each.


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