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  1. #1
    Join Date
    May 2008
    Posts
    40

    Efficiency Disappointment?

    Well, it has been one month since my new Lennox XP 19 Heat pump and variable speed furnace has been in use. I am surprised to find that it is using more energy than my 22 year old Lennox 6 SEER. The system is working great in terms of cooling, but the energy use is 18% greater and when adjusted for my hot tub power being turned off at the same install time, the difference is even greater. The t-stat settings have been the same as before and when I look at the high outdoor temp and take that into account for that increase in June’s energy use it is still baffling why the new Lennox is more of a energy hog. Nothing else in the house has changed. The figures below came from my power company. I installed the new dual fuel system on May 30, 2008.

    Is it possible that something is set up wrong? Thoughts?

    Date, Total kWh, Max Outdoor Temp
    06/26/08, 116, 88
    06/25/08, 119, 93
    06/24/08, 108, 86
    06/23/08, 94, 84
    06/22/08, 106, 86
    06/21/08, 109, 86
    06/20/08, 85, 83
    06/19/08, 121, 86
    06/18/08, 90, 84
    06/17/08, 80, 82
    06/16/08, 96, 78
    06/15/08, 98, 82
    06/14/08, 97, 86
    06/13/08, 122, 82
    06/12/08, 108, 85
    06/11/08, 116, 88
    06/10/08, 110, 84
    06/09/08, 114, 74
    06/08/08, 113, 87
    06/07/08, 149, 87
    06/06/08, 100, 83
    06/05/08, 100, 85
    06/04/08, 107, 88
    06/03/08, 105, 89
    06/02/08, 110, 81
    06/01/08, 99, 88
    05/31/08, 98, 89
    Install Date
    05/30/08, 112, 88
    05/29/08, 93, 84
    05/28/08, 83, 72
    05/27/08, 99, 78
    05/26/08, 134, 81
    05/25/08, 147, 89
    05/24/08, 100, 78
    05/23/08, 92, 78
    05/22/08, 96, 71
    05/21/08, 98, 75
    05/20/08, 109, 73
    05/19/08, 115, 83
    05/18/08, 126, 79
    05/17/08, 122, 86
    05/16/08, 93, 78
    05/15/08, 96, 70
    05/14/08, 87, 68
    05/13/08, 105, 77
    05/12/08, 94, 75
    05/11/08, 82, 64
    05/10/08, 96, 63
    05/09/08, 91, 66
    05/08/08, 100, 73
    05/07/08, 95, 69
    05/06/08, 101, 75
    05/05/08, 85, 76
    05/04/08, 97, 70
    05/03/08, 71, 61
    05/02/08, 83, 72
    05/01/08, 126, 82
    04/30/08, 91, 80
    04/29/08, 62, 64
    04/28/08, 69, 54
    04/27/08, 76, 59
    04/26/08, 63, 63
    04/25/08, 73, 72
    04/24/08, 100, 74
    04/23/08, 93, 76
    04/22/08, 103, 74
    04/21/08, 79, 78
    04/20/08, 109, 78
    04/19/08, 96, 65
    04/18/08, 82, 61
    04/17/08, 78, 67
    04/16/08, 64, 75
    04/15/08, 67, 71
    04/14/08, 75, 57
    04/13/08, 81, 49
    04/12/08, 68, 43
    04/11/08, 64, 49
    04/10/08, 62, 69
    04/09/08, 68, 57
    04/08/08, 69, 48
    04/07/08, 62, 57
    04/06/08, 118, 69
    04/05/08, 112, 64
    04/04/08, 74, 59
    04/03/08, 78, 50
    04/02/08, 72, 59
    04/01/08, 74, 49
    03/31/08, 100, 74
    03/30/08, 95, 61

  2. #2
    Join Date
    May 2007
    Location
    Naples, Fl
    Posts
    889
    Just looking at April 22 and 23 yes there is something wrong somewhere new unit or other wise.

  3. #3
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,756
    usage #s on days with the same temp are all over the place.......


    sumptin ain't right, don't know if the unit or something else in the house.

    i would think if the unit the #s on the warmer days would all be higher.

  4. #4
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,587
    If you're home isn't insulated properly and you have leaky windows and doors. Basically an older home. It doesn't matter what SEER rating you put in if it can't keep cold in and hot out or vice versa. You really need to look at the entire picture and not think that a fancy A/C system is gonna solve the problem. Maybe the ducts are too small as well, is the return undersized? It could be setup wrong. I've setup a few, they aren't that hard, but you do have to wire everything and cut jumpers and set dipswitches.

  5. #5
    Join Date
    Mar 2007
    Location
    Madison, Wisconsin
    Posts
    2,260
    For 20 days before new system average temp was 80.5, and average KW 108.95
    For 20 days after install average temp was 88.55, and average KW 110.9

    Those numbers look better to me

    What about relative humidity? You may be jumping the gun a little here. try comparing this summer to last summer. I am not saying that the new system is set up properly, there is not enough information to tell that from your post. And this is a kind of small sample. The numbers change a lot from day to day there so there must be a lot of other variables in this picture....
    I r the king of the world!...or at least I get to stand on the roof and look down on the rest of yall

  6. #6
    Join Date
    Jan 2007
    Location
    N.E. Ok.
    Posts
    1,371
    Were their any modifications made to the 22 yr. old duct work ?

    Post some pictures and ductwork sizes.

  7. #7
    Join Date
    Jun 2008
    Posts
    48
    wow, those numbers are all over. There are other things afoot!

    Clay

  8. #8
    Join Date
    Jan 2004
    Location
    Burleson, Texas
    Posts
    1,741
    Does this system have dehumidification controls?....

  9. #9
    Join Date
    Apr 2008
    Location
    TEXAS
    Posts
    1,701
    ya gotta go by average. you can't cherry pick days with high usage or low temps. if your light bill is higher overall, maybe you should request an energy audit from the elect. co.
    "When the people find they can vote themselves money,that will herald the end of the republic" - Benjamin Franklin

    "Government is not reason, it is not eloquence, it is force;like fire, a troublesome servant and a fearful master. Never for a moment should it be left to irresponsible action"- George Washington

  10. #10
    Join Date
    Jun 2008
    Posts
    48
    wow, those numbers are all over. There are other things afoot!

    Clay

  11. #11
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,915
    Quote Originally Posted by captube View Post
    Were their any modifications made to the 22 yr. old duct work ?
    That's what I'm wondering. If it is the same old duct system as the old system had, and has the air leaks and inadequate insulation that are typical of old duct systems, heat gain and duct leakage will cripple 1st stage of a new 2 stage system.
    When it is installed on an old leaky and poorly insulated duct system, it is not uncommon for a new ultra efficient 2 stage system to actually use more energy than the old inefficient 1 stage system did.

    The reason this can happen is that the old system had enough capacity to still cool the house, despite the duct leakage and heat gain.
    The new 2 stage system doesn't have enough capacity in 1st stage to overcome the duct leakage and heat gain, which is increased due to the lower velocity airflow in 1st stage, and still cool effectively, so you end up with much longer run times, and the system going into 2nd stage much more often.
    We will see this more and more often due to the proliferation of 2 stage equipment.

    I'm not saying that this is what is happening in this case, just pointing it out as a possibility.
    If more government is the answer, then it's a really stupid question.

  12. #12
    Join Date
    Mar 2005
    Location
    Indianapolis, IN
    Posts
    241
    What a mystery...

    You replaced 3T heatpump with 4T variable speed unit....
    What you really expected? That your new unit would be so efficient electric company will be paying you to use it?

    Next you added IAQ and set humidity control.

    And this on 60 years old house?

    Wow....

    I tell all my clients same thing. There is always something better, don't upgrade cause of some bells - upgrade when you have to. Expect new features to be added bonus.

  13. #13
    Join Date
    Dec 2006
    Location
    Dallas
    Posts
    189
    A current clamp would tell a lot, but since you didn't already, you don't have one. Your backwards rolling date gives me a migrane...

    Comparing the ratio of daily KWH consumption to daily high deviation from (lets say 70F), Appears that you have an electric dryer, and you do laundry 50% consistantly on Sunday nights, registering for Mondays? Is your spa electric? Appears that during the two months of log, you used it only on: Wed 5/7/2008 and Thursday 5/22/2008.

    Since the plot started, you have gone from little heating season to cooling season, so analyzing the data is a bit complex.

    Turn the HVAC off for 24 hours and carry on with your other consumption. Do you know at what time the KWH log starts? If so, turn the HVAC off that moment for 24 hours. If you don't know the start and stop time, turn the HVAC off for 48 hours. You will have at least on full 24 hour period with the HVAC off, which should be obvious in the KWH report.

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