Energy Savings. Where are they?
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  1. #1
    Join Date
    Jan 2005
    Location
    Williamsburg, VA
    Posts
    386
    In February I replaced my 15-year old Trane XE800 heat pump and single speed air handler with an XL16i and matching variable speed air handler effectively going from a 10 SEER unit to a 17 SEER state-of-the-art system.

    Today I just received my first electric bill using the new system and I don't see any savings at all. Now keep in mind that it's somewhat difficult to compare Apples to Apples since the average monthly temperature was different this year versus last.

    I don't know the formular for calculating energy effieciency but perhaps someone here may. Here is my latest usage:

    Mar 05 - 29 days - 3583 kWh - Avg daily use 123.6 - Avg temp 36
    Mar 04 - 31 days - 2764 kWh - Avg daily use 89.2 - Avg temp 42

    On both systems I have a programmable thermostat and used the exact same settings. 68 degrees during the day, 65 degrees at night (11:00 PM - 6:00 AM).

    The only thing that may be negatively affecting my energy efficiency is that I had an Aprilaire whole house humidifier installed at the same time and the HVAC tech connected it to the hot water line. Of course their may be some other issues as well. I appreciated any suggestions or advice.

    Thanks,
    Kelly

  2. #2
    Join Date
    Apr 2004
    Location
    Niantic, Illinois
    Posts
    545
    It may be possible the power company estimated the power usage for the month as well.

  3. #3
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,273
    I had an Aprilaire whole house humidifier installed at the same time and the HVAC tech connected it to the hot water line.
    WHOOPS!

    Off the cuff I'd say a month's time is not enough to conclude anything yet. And keep in mind your heat pump isn't the only thing in the house spinning the electric meter. Was there other things going on compared to the previous year?

    Also if I recall correctly you had some kinks in your system to iron out before you got some decent performance out of it.

    How's your overall comfort with this system compared to your old one?
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  4. #4
    Join Date
    Jan 2005
    Location
    Williamsburg, VA
    Posts
    386
    According to the statement these are actual numbers. The billing period is Feb 15, 2005 - Mar 16, 2005. The meter was read on Mar 16th.

    Just for fun the usage for the month prior was 5122 Kwh. This was when my old XE800 was running on emergency heat almost the entire month.

  5. #5
    Join Date
    Jul 2004
    Location
    West TN
    Posts
    983
    Going from the lower seer unit to the higher seer unit, you should get a savings, its really hard not to.

    Things that can effect the effeciency in a negative way would be....
    Air leaks left during replacement of equipment
    Improper refrigerant charge

    Being that your average temp was so low...
    your unit may have been cycling on the aux heat alot more than the prior year you are refering to. The aux heat can use about 3 times as much electricity when it kicks in
    (unless you use another source of heat for aux heat other than electric heat strips such as gas). The aux heat will start kicking in at around freezing. The actual temperature varies from house to house, but should be close to freezing.

    Out of curiosity... where you more comfortable with the new system?



    Extend to others the grace that God has given you.

  6. #6
    Join Date
    Jan 2005
    Location
    Williamsburg, VA
    Posts
    386
    Off the cuff I'd say a month's time is not enough to conclude anything yet. And keep in mind your heat pump isn't the only thing in the house spinning the electric meter. Was there other things going on compared to the previous year?

    Also if I recall correctly you had some kinks in your system to iron out before you got some decent performance out of it.

    How's your overall comfort with this system compared to your old one?
    I was thinking that too. No, there's nothing else that we're running today (electric wise) that we weren't running last year.

    Yes, all of the kinks (mostly cosmetic) were worked out. If the heat pump isn't charged properly will that affect performance? By the way, I am purchasing the 10-year Trane extended warranty just in case.

    The comfort is great! The air actually feels a little warmer than my old system and it's much quieter.

    [Edited by kcrossley on 03-22-2005 at 12:36 AM]

  7. #7
    Join Date
    Jan 2005
    Location
    Williamsburg, VA
    Posts
    386
    Originally posted by wormy
    The aux heat will start kicking in at around freezing. The actual temperature varies from house to house, but should be close to freezing.
    Good point.

    By the way, I recall the installer saying that he charged the system but because the termperatures were so low when it was installed (around 20 degrees) he needed to return in the spring when the weather is warmer to more accurately measure the charge and adjust it accordingly. Is this true?

    By the way, my new thermostat which is a VisionPro 8000 doesn't seem to indicate when auxilary heat is running. Am I missing something?

    [Edited by kcrossley on 03-22-2005 at 12:39 AM]

  8. #8
    Join Date
    Jul 2004
    Location
    West TN
    Posts
    983
    Here's a closer look as to what your weather looked like last year....

    March 2004...
    http://www.wunderground.com/history/....html#calendar

    March 2005...
    http://www.wunderground.com/history/....html#calendar


    Looks like this year saw alot more potential for aux heaters than last year.
    Extend to others the grace that God has given you.

  9. #9
    Join Date
    Jul 2004
    Location
    West TN
    Posts
    983
    Yes... its a bit harder to charge one correctly when its that cold outside.

    Unless he can get accurate line set lengths and calculate it (my prefered method)... sometimes thats not possible though.
    Extend to others the grace that God has given you.

  10. #10
    Join Date
    Jan 2005
    Location
    Williamsburg, VA
    Posts
    386
    Great web site! Yes, there were some pretty cold days this year. When is the earliest I can have him properly charge the system?

  11. #11
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,829
    The Vision Pro does tell you when the backup is on. Instead of Heat on it says Aux heat on under the set temp.

    I noticed something and haven't gotten any responses. I have a Vision Pro set up on my test bench checking out a twinning kit I made. It's set for 2 stage heat pump plus backup. The set temp has to be 5 degrees above ambient temp for the backup to turn on. I can't see that leading to a comfortable house. How close to set point does your system run?

  12. #12
    Join Date
    Jan 2005
    Location
    Williamsburg, VA
    Posts
    386
    Originally posted by BaldLoonie
    How close to set point does your system run?
    I have never seen the AUX HEAT indicator on since I've had the system. It may be that I have this set wrong. My recollection is that it's set on HEAT. It sounds like it should be set on AUTO if this is an option.

    My system runs within a few degrees of the set point.

  13. #13
    Join Date
    Jul 2002
    Location
    Zelienople, Pa
    Posts
    2,965
    I'd bet the system isn't set up correctly.

    Didn't you have it installed by an unauthorized Trane dealer?
    With as sloppy as your install looked, what makes you think it was charged and started properly?
    Hire a reputable contractor to look it over and send the bill to the installer if anything is majorly wrong.
    How tall are you Private???!!!!

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