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  1. #1
    Join Date
    Jan 2005
    Posts
    31
    We have a new home in Kansas City, MO. 2-story, approx. 2000 sq. ft (1000 up, 1000 down). We have a Lennox Merit Series furnace (I believe it's a 4-ton) & heat pump.

    The home originally came with a basic, non-programable thermostat. We paid a handsome amount to the same contractor who installed the system for an X4147 thermostat.

    We have the settings on cool and the fan is set on auto. Lately it has been quit warm (low to mid 90s). We set it at 77 or 78 when we're gone during the day and kick it down to 75 or 76 when we get home. We have the duct baffles set so it gets quit comfortable, sometimes chilly, both upstairs and down. We have had all of our window treatments up for more than a month.

    Our problem is that the inside temp gets down to the set point usually within 30 minutes no matter how hot it has been. But once the temp has reached the set point, both the furnace and the heat pump will continue to run and run and run (sometimes more than an hour). The inside temp reading will stay at set point. After a while I will kick the set point up one degree and then the system will begin to act like it should (coming on every now and then for a little while and then shuting off). We have not placed a thermometer next to the thermostat yet but will tomorrow. I will not be surprised if the room temp gets 2 or 3 degrees lower than the set point.

    We called the contractor. He really didn't say if the 'cool' should run that long after the set point but did say there could be a problem with the outside sensor or the thermostat. Funny thing is, when he originally came out and installed the X4147 he didn't install a sensor that displays the outdoor temp (unless he's talking about a different sensor). When he came out he installed a different X4147 and installed an outdoor sensor.

    This is where I start to question the tech's knowledge of the X4147 or the entire system. First, he told my wife that he either forgot or did not program the original X4147. Second, the outside temp that day did not get above 93 degrees and the outside temp. on the thermostat was reading 105 degrees at 1830 hours when the temp had dropped to 89 degrees. After looking outside and not finding where he had mounted the sensor, I opened the service panel on the heat pump. The guy had just left it rolled up inside there. After removing it the temp. immediatly read correct(or close).

    I called another contractor in my area who said that it's not normal for the heat pump to run for so long after the set point is reached.

    Can anyone tell me if my system is running properly or if there is something the tech is missing?

    Thanks for any help

    TJ

  2. #2
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,709
    does thermostat have dehumidify feature?? if that is turned on it could cause symptoms described. not familiar with that part # and not at office to look up.

  3. #3
    Join Date
    Nov 2001
    Posts
    1,874
    1st off, I hate to hear that people build a place then pull back on the $$ when their comfort is concerned.

    The price difference from the merrit to the elite is not much, or even better yet the signature line. but the warranty is better.

    Anyway, I'm not familiar with that stat, but any digital sat should cycle within as little as a 1/2* of the desired temp.
    Those that have the auot change over could ask that there be as much as a 4* difference from heat to cool to prevent the system from battleing itself.

    The sensor should be located away from direct sun or any heat source. And not inside the cabnit.
    It shoud reach the desired set point and shut down.
    If you try to fail, and succeed.
    Which have you done ?



  4. #4
    Join Date
    Jan 2005
    Posts
    31
    Thanks for the advice fellas. I thought the system should shut down when the set point is reached. As for the money issue, if we had known the differences between the elite and the merit, we would have jumped on the elite. The merit is what our builder specs out and we assumed it was a good system (I hope it is, just not as good as the merit).

    TJ

  5. #5
    Join Date
    Nov 2001
    Posts
    1,874
    It's not often that we gte the chance to talk to the H/O'er
    If we did, most of the time we could sell them up to the better equipment, which holds better warranties.

    Most of time they can find somewhere to cut the corners to make the upgrade.

    But as stated above it could be the stat is sensing it needs to run the blower to help de-humidiy alittle more.
    If you try to fail, and succeed.
    Which have you done ?



  6. #6
    Join Date
    Nov 2001
    Posts
    1,874
    It's not often that we get the chance to talk to the H/O'er
    If we did, most of the time we could sell them up to the better equipment, which holds better warranties.

    Most of time they can find somewhere to cut the corners to make the upgrade.

    But as stated above it could be the stat is sensing it needs to run the blower to help de-humidiy alittle more.
    If you try to fail, and succeed.
    Which have you done ?



  7. #7
    Join Date
    Apr 2005
    Location
    Tampa, Florida
    Posts
    1,634
    I'm not familiar with the Lennox model #'s... if you have a 2-stage condensing unit with multi-stage thermostat, then the behavior you describe sounds normal. A 2-stage system will start off on the lowest stage of cooling, then use the second stage if the first stage isn't cutting it. When the temperature is close to satisfied, the thermostat will go back to low and rely upon that to finish the job or maintain the temperature.

    As far as the outdoor temp sensor, that should be located where it can sense the outdoor temp without major interference from the sun, building, mechanical heat sources, etc.

  8. #8
    Join Date
    Feb 2003
    Location
    garland, texas
    Posts
    666
    Set a fan of some variety about 10-20 feet away from stat. Stat should be between fan and return. Turn fan on and aim toward stat. If this shortens run times and still cools house to desired temp then consider moving stat.

  9. #9
    Join Date
    Jan 2005
    Posts
    31

    Frown

    Think I may have discovered my problem. I spoke with someone at Lennox today who said that the tech hooked up the wrong stat. We have a 1-stage system which takes a X4146 stat. The X4147 is designed to be used with a 2-stage system. I guarantee we'll be staring down the barrel of a $200+ electric bill this month. I'd like to ask the HVAC contractor if he's going to split my bill with me.

    TJ

  10. #10
    Join Date
    Apr 2005
    Location
    Tampa, Florida
    Posts
    1,634
    With a few exceptions, there's usually no harm in putting a 2-stage stat on a 1-stage system... if anything, the installer used a more expensive stat than necessary.

  11. #11
    Join Date
    Jan 2005
    Posts
    31
    Bottom line is, Lennox says there is a problem and more than likely that problem is the wrong thermostat is being used.

    TJ

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