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  1. #1
    Join Date
    Sep 2008
    Posts
    20

    EER and fan speed

    I live on a Tropical Island next to the ocean. The maximum temperature is 95, below 82 we turn the air conditioning off. It never goes below 75. Last year my Trane 14 SEER ran 750 hours total, about 4 hours per day, on less than 200 days. The Trane condensing unit is pretty corroded after 6 years and a few salt water baths in storm season, but the other brands rusted away in 2-3 years.

    It seems like we are more subject to EER than SEER, It looks from the literature like 18-21 SEER is actually only 14 EER, and 14 SEER is 11 EER with little real power savings for the large cost differential under our weather conditions, or am I missing something (especially since it will rust out in a few years).

    The air handler is fine but the dealer is saying to get better SEER he needs to change it when he changes the condenser, but if I understand what i've been reading for all the money over just putting on a new condenser I may only save a small amount on the electricity cost. The comfort and dehumidification are fine.

    One more question, the Trane airhandler is three speeds and cools fine on any of them but is a little noisier on high. Is any speed likely to produce better EER than another?

    Thank you!

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,880
    A new 13 SEER condenser on an old 10 SEER coil. Will usually have less capacity.
    Which means it will have to run longer. And at your design condition days, may not handle the load.

    Its not the indoor blower, its the indoor coil that lowers the efficiency.
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  3. #3
    Join Date
    Sep 2008
    Posts
    20

    EER on Tropical Island

    Sorry if I didn't make it clear. I have a six year old two ton 14 SEER 410 system. The condensers don't last because of the salty conditions. If there is less difference in EER (actual operating cost) than SEER at the temperatures the system works at here, is it worth replacing the air handler to increase the SEER (but maybe not the actual EER very much).

    Also, I've read the SEER is calculated as an average of the available fan speeds, is one particular speed likely to be more efficient than another, particularly with the high humidity, average over 80 percent?

    Thank you

  4. #4
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    SEER is calculated over various outdoor temps,not fn speeds.

    Your system may operate at various fns speeds for dehumidification,so SEER will vary.

    Pot the model numbers or the air handlers,they may be a good match with your new outdoor unit,or not.

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,880
    Unless your A/C runs virtually continuous, EER isn't actual operating cost.

    Being 14 SEER, good chance their is a condenser from your brand that will match.

    Post mod numbers as Dash requested.
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  6. #6
    Join Date
    Sep 2008
    Posts
    20

    EER vs SEER

    In my original post I mentioned it runs 750 hours per year. It fairly consistently draws 1900 watts total

    Air handler 4TEP3F24A1000AA
    Condenser 4TTX40241000AA

    Outdoor temp is fairly consistent, 80-95 never hotter, off when cooler. We keep the indoor temp at 82.

    My question is given we know the running hours and ambient temp from years of experience, should we calculate costs and possible savings on more efficient equipment using EER or SEER?

    Thank you!

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,880
    SEER.

    Since you didn't say it runs for an hour plus when its 85 outside.

    So, if it cycles on and off, use SEER.

    Operating cost, for your posted temp span. Should be based on the 3 bins for those temps. Not for the total cooling seasons hours.

    Since you don't have that info, SEER used on the total hours will work good enough.
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  8. #8
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by jimblu View Post
    Air handler 4TEP3F24A1000AA
    Condenser 4TTX40241000AA
    I don't see a 4TEP air handler in the AHRI website: www.ahridirectory.org

    With a 4TTX4024 condenser,
    4TEC3F24 gets 11.2 EER, 13.25 SEER
    4TEH3F24 gets 12 EER, 14.5 SEER

    Good luck

  9. #9
    Join Date
    Jun 2007
    Location
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    Quote Originally Posted by jimblu View Post
    Outdoor temp is fairly consistent, 80-95 never hotter, off when cooler. We keep the indoor temp at 82.

    My question is given we know the running hours and ambient temp from years of experience, should we calculate costs and possible savings on more efficient equipment using EER or SEER?

    Thank you!
    If you are considering replacing a single stage condenser with another single stage condenser, I would use the ratio of the EERs to determine your potential cost savings. Even though SEER takes into account inefficiencies due to on/off cycling and time to reach full efficiency, your ambient temps are fairly high and SEER is geared to lower ambient temps.

    If you have a fixed speed fan in the air handler,
    SEER = EER (at 82F ambient) x fudge factors.

    If you have a variable speed fan in the air handler, SEER = EER calculated across the following range of temps:

    Ambient-----Weight %
    Temp-------in SEER calc

    67F---------21.4%
    72F---------23.1%
    77F---------21.6%
    82F---------16.1%
    87F---------10.4%
    92F---------5.2%
    97F---------1.8%
    102F--------.4%
    ------------------
    Total = 100%

    Since you state that your ambients are consistantly 80 - 95F, the first 3 bin temps do no apply to you. These lower 3 bins are 66% of the value of the SEER calculation for a v-s motor.

    If you have a variable speed air handler, and are considering an upgrade to a 2-stage condenser (usually 16 SEER and higher), the 2-stage condenser lowers operating costs when it runs on first stage because of higher EERs on first stage compared to second stage. You may not recover the additional $$ in energy savings to purchase the 2-stage condenser over the life of the equipment.

    Good luck.

  10. #10
    Join Date
    Sep 2008
    Posts
    20

    EER on Tropical Island

    Thank you! Exactly the information I needed. I don't have variable speed now, that's what makes an upgrade so much more expensive than just replacing the condenser. The contractor talked about significant savings with 21 SEER, but it looks more like payback on higher SEER equipment would be over ten years, and it corrodes away in six

    I really appreciate everyone's help

  11. #11
    Join Date
    Jun 2007
    Location
    The Twilight Zone
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    Quote Originally Posted by jimblu View Post
    The contractor talked about significant savings with 21 SEER.....
    Most advertised 21 SEER systems are stated as "up to 21 SEER", meaning that only a few models in the line-up achieve 21 SEER. The rest of the models achieve more like 16 SEER.

    The new IQ Drive from Nordyne, with a variable speed compressor in the condenser, is a true 23 SEER in the 2-ton size, and 21 SEER in the 3 and 4 ton sizes. You would need the matching Nordyne air handler.

    Take care.

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    Quote Originally Posted by gary_g View Post


    Since you state that your ambients are consistantly 80 - 95F, the first 3 bin temps do no apply to you.


    Good luck.
    Now ask him, if his area has more hours near the 80° temp, or more hours at the 90° temp.

    I think you'll find that areas with his temp range. Have A/C's that cycle at temps higher then what you live in.
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  13. #13
    Join Date
    Sep 2008
    Posts
    20

    Tropical Island cooling

    Average temps near upper 80's. At 80 we open the windows, at 82 it runs very little. At 95 it runs about 1/3 of the time but it is only 95 for a few hours in the afternoon and always drops to the 80's when the sun goes down. The average cooling day temp is probably in the mid to upper 80's. We are surrounded by an 82 degree ocean and don't have hot nights.

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