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  1. #1
    Hello, and thanks in advance for helping.

    I have a dead (failed compressor) 1988 Carrier heat pump that needs to be replaced. I am considering various options, from outdoor unit replacement only to whole new systems of various efficiencies.

    The current Carrier system is:

    38QN036310 outdoor
    40QB042300 indoor

    My most basic question is - what is the SEER and HSPF of this system?

    Also - is it likely to have degraded in efficiency in its last year or so of life?

    If I buy a basic 10 SEER outdoor unit, am I likely to see approximately 10 SEER (fnd matching HSPF)from the resulting system?

    Any real reason to replace indoor unit? Blower motor was new a year ago.

    Reason for the questions is my attempt to figure running cost savings using recent energy bills as a baseline. I've only owned the house for a year and a half so I don't know how the system behaved when new, but bills have been high leading up to failure. Any replacement will be professionally installed.

    Also, would it be smart or dumb to bump the outdoor unit size up to match the indoor unit, in order to reduce strip heater use in winter? We're in Richmond VA and heating bills are usually higher than cooling.

    Thanks!!

  2. #2
    Join Date
    Sep 2004
    Posts
    3,157
    I could be wrong about this but I dont believe they had a seer rating in 1988-

    is it likely to have degraded in efficiency in its last year or so of life?

    of course it is likely to have degraded in efficiency
    worn out , overheated , burnt mechanical devices dont work as well as they did when they were new

    Any real reason to replace indoor unit? Blower motor was new a year ago.
    There is a real good reason to replace the indoor unit even though the motor was replaced a year ago.

    one of those reasons are because the indoor coil must be matched to the system you are having installed.


    Also, would it be smart or dumb to bump the outdoor unit size up to match the indoor unit, in order to reduce strip heater use in winter? We're in Richmond VA and heating bills are usually higher than cooling.


    Its not a matter of being smart or dumb, but what you need to do to achive the comfort you expect , and that would be to have a competant HVAC contractor come out and determine the proper size system for your home including the proper duct sizing and airflow for the system you choose

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,189
    8.5 SEER 6.4 HSPF


  4. #4
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    If you "bump" the size,the ducts are likely too small for the increased air flow required.Plus it won't run as much in the summer to dehumidify the air in your home.Assuming it has cooled well in the summer,don't oversize it,it may be oversized already.

  5. #5
    Thanks for feedback!

    One follow-up question -

    On the current system, the outdoor unit is a 3T and the indoor a 3.5T. Is this common practice, and what is the reason?

    Best Regards!


  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,120
    Yes its common, and its done mostly for eff.
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