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  1. #1

    Replace compressor or entire unit formula?

    Hello,
    I have an 11 yr old 4 ton comfort maker...8 seer?..The compressor has gone out, tripping breaker etc..HVAC guy, who I do trust and have used for several yrs..has ckd everything out and says compressor is bad. To replace compressor he says it is about $1200, a new 14 seer American standard w variable speed motor and some additional duct work(since old unit is horse shoe type and new wouldnt be) is about $5,700.

    I'M NOT asking about bid/price etc..rather is there a rule of thumb or formula that can be used to see if one way or the other is best?..

    Also in general is there a rule of thumb about how to calculate how much savings is realized per seer unit..ie the difference b/w 8 and 14.. how much in general would that save per month?..I know it depends on what part of country etc..Im just looking for ball park..I live in TN
    Thanks for the help
    Joseph1

  2. #2
    Join Date
    Apr 2007
    Location
    Philadelphia
    Posts
    2,192
    Yes here is the formula..
    11 yrs old + 8 seer = New unit

  3. #3
    Join Date
    Feb 2003
    Posts
    35

    New Unit

    I would replace entire unit because even if the compressor is replaced other things could fail on the older unit and your then faced with another service call, more parts. When if you have a new unit then any problems are warranted.

  4. #4
    Join Date
    Apr 2007
    Location
    Philadelphia
    Posts
    2,192
    Quote Originally Posted by tomwr1958 View Post
    I would replace entire unit because even if the compressor is replaced other things could fail on the older unit and your then faced with another service call, more parts. When if you have a new unit then any problems are warranted.
    Plus you dont know what caused the compressor to die, most likely something did, So do you have more problems??? Would you like to put a compressor in and then pay more to fix another problem?? being 50 or 500 bucks???

  5. #5
    Join Date
    Jan 2008
    Posts
    18
    I'd definitely invest in a new system. Anytime a 10 seer or below needs major service, I would replace with higher efficiency. I would also get some more quotes. Trusting the guy you have known or used for a few years doesn't mean he can or will give you the best bang for the buck or service for that matter.

  6. #6
    Join Date
    Jan 2008
    Posts
    18
    BTW....this shows as my first post. I did register and post here a few times about three years ago. I couldn't remember any of my log in info and the email I used back then is long gone so I couldn't access the lost ID/password info..
    I re-registered.
    So this is not really my 2nd post to this board.
    Back then, when I was looking for HVAC forums for info etc, this was the number one I found references too. And it still seems to be.
    That must be a good thing.

  7. #7
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,247

    Thumbs up $ Savings Example

    Quote Originally Posted by Joseph1 View Post
    Also in general is there a rule of thumb about how to calculate how much savings is realized per seer unit..ie the difference b/w 8 and 14.. how much in general would that save per month?

    ..I know it depends on what part of country etc..Im just looking for ball park..I live in TN
    Summer savings = 40% of the electric usage for COOLING.

    For example, you spend $200 on ALL your electricity.
    Say, for a medium to large ( 3,000 square foot) residence, energy cost for COOLING might be ~ $130 per month for 4 or 5 months. (given 8 SEER and) or $650 + per year.

    http://www.alliantenergy.com/docs/gr...b/p013445.hcsp

    4 tons ... 1400 hours ... $0.08 ... 8 SEER ... $672
    4 tons ... 1400 hours ... $0.08 ...13 SEER ... $414
    4 tons ... 1400 hours ... $0.08 ...14 SEER ... $384

    One might save upto $300/year in a hot TN summer
    where actual operating hours ( ~ 1400) are quite significant
    and one pays $0.08 per kwh.

    Similar results with other calculating tool from link
    http://www.hvacopcost.com/

    Obviously, with a 1400 square foot residence, the
    cooling energy cost savings would be closer to $140 per year.
    Last edited by dan sw fl; 01-31-2008 at 06:46 AM.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  8. #8
    Join Date
    Jan 2008
    Posts
    10
    Please do not spend the money to repair your current machine. If you calculate all related expenses ( 8 seer energy usage, current and future repairs, inflation of replacement cost in a few more years.) you will be MUCH less out of pocket investing in a new machine today, rather than 2-8 years.
    Reguarding efficiency: not only do you save on energy usage with higher seer ratings, but you also get a lot higher quality machine across the board when looking at all the variables(noise levels, longevity, service costs, performance, internal protection devices, crankcase heater, low pressure and high pressure controls etc..)

  9. #9
    Join Date
    Jan 2008
    Posts
    10
    Quote Originally Posted by Dustin-H View Post
    Please do not spend the money to repair your current machine. If you calculate all related expenses ( 8 seer energy usage, current and future repairs, inflation of replacement cost in a few more years.) you will be MUCH less out of pocket investing in a new machine today, rather than 2-8 years.
    Reguarding efficiency: not only do you save on energy usage with higher seer ratings, but you also get a lot higher quality machine across the board when looking at all the variables(noise levels, longevity, service costs, performance, internal protection devices, crankcase heater, low pressure and high pressure controls etc..)
    The sweetness of low price does not last as long as the bitterness of poor quality.

  10. #10
    Join Date
    Aug 2004
    Location
    Kentucky, Michigan, Ohio, Arizona, Colorado, Nevada, and Califormia
    Posts
    318
    The advice given has been good. Take it. Additionally, you mentioned the breaker tripping. If the compressor is grounded, you'll likely have acid in the system and if not cleaned up (@ additional considerable expense) will lead to very premature failure of the repair. New unit, New unit, New unit.
    "Surprised ?! If I woke up tomorrow with my head sewn to the carpet, I wouldn't be more surprised."
    Clark Griswold

  11. #11
    Join Date
    Jun 2007
    Location
    Pigeon Forge, TN
    Posts
    295

    I would replace whole unit

    where in Tennesse are you I'm in Pigeon Forge

  12. #12

    Thumbs up Hvac replacement

    I live around Nashville area..we visit Gatlinburg / PF area every couple of yrs!
    Thanks for all the input everyone!!!

  13. #13
    Join Date
    Nov 2007
    Location
    maryland
    Posts
    17
    just get a good unit realize a 6 to 8 % fuel savings for every seer point

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