Question about upstairs system
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  1. #1
    Join Date
    Sep 2012
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    373

    Question about upstairs system

    Now that the issues are corrected for my main level system, I now have a question about my upstairs HVAC system.

    I had a Lennox SL280v gas furnace installed last July. This week has been pretty chilly here in Georgia. We have been having comfort issues in our 3 bedrooms upstairs, and they haven't started yet until the temperatures got pretty cool here outside. The thermostat is located in one of the bedrooms which has high ceilings. The other two bedrooms have standard 8 ft ceilings. I have noticed that the temperature in the room with the high ceilings is always a few degrees warmer than the others. For example, during the afternoon that room was 69*F and the other two rooms were both 64*F. The doors were open all day. Plus, the bedroom with high ceilings has curtains over the window and faces the sun the majority of the day. I would assume that could be part of the cause of the unbalanced temperatures. My son has been complaining that his bedroom has been cold in the afternoon right after he gets home from school. My daughter's room is the room with the high ceilings and her room feels nice. The third bedroom is the guestroom, which is hardly used. We had our attic insulation evaluated last summer and the contractor said that the insulation was all fine. The furnace has also been having very short cycles as well (like in the 3-4 minute range).

    What could possibly be a good solution to solve the unbalanced temperatures upstairs? We do plan to have a service tech out soon if this problem continues.

  2. #2
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
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    2,584
    Are the registers in the ceiling? Is that furnace a 2-stage or modulating furnace? Where are the return air grilles?

  3. #3
    Join Date
    Sep 2012
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    373
    The furnace is 2-stage. The registers are in the ceiling. There are 2 returns in the hallway and there is 1 return in each room.

  4. #4
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
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    Okay, thanks for the infomation. I don't like to use 2-stage equipment in that situation because when the furnace starts on low fire, you'll get a low speed fan (blower) which doesn't make much sense with the registers (high) in the ceiling.

    But, that said, I don't understand why the furnace is short cycling so much. You might want to run the blower on constant blower to see if that make a difference.

    Also check the filter to make sure it's clean.

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,627
    Thermostat CPH may be set too high. While having the stat in the room with the high ceilings is a good idea for the cooling season. It can give problems in the heating season.
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  6. #6
    Join Date
    Sep 2012
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    373
    Quote Originally Posted by George2 View Post
    Okay, thanks for the infomation. I don't like to use 2-stage equipment in that situation because when the furnace starts on low fire, you'll get a low speed fan (blower) which doesn't make much sense with the registers (high) in the ceiling.

    But, that said, I don't understand why the furnace is short cycling so much. You might want to run the blower on constant blower to see if that make a difference.

    Also check the filter to make sure it's clean.
    I replaced the filter over a month ago. We use lower quality pleaded filters because they are better than cheap fiberglass filters in my opinion. Your opinions could be different though. Our old furnace had no problems with it. We just wanted to upgrade to variable speed. I'll see if running the blower in continuous fan speed will help. But I'm just wondering why the furnace has short cycles. It's not set up for two stage, so the furnace will run on low for 7 minutes and then switch to high.

  7. #7
    Join Date
    Sep 2012
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    Quote Originally Posted by beenthere View Post
    Thermostat CPH may be set too high. While having the stat in the room with the high ceilings is a good idea for the cooling season. It can give problems in the heating season.
    That could be the issue, but I really don't know. Sometimes we have short cycles in cooling mode as well.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    Setting the thermostat to a lower CPH for heat, and for cooling may help.
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  9. #9
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    Sep 2012
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    Quote Originally Posted by beenthere View Post
    Setting the thermostat to a lower CPH for heat, and for cooling may help.
    Thanks beenthere. The Thermostat is a Honeywell RTH6450D just incase that might help.

  10. #10
    Join Date
    Sep 2012
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    373
    I am also wondering if the blower cfm is set too high.

  11. #11
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
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    4,135
    Upstairs in GA probably requires very little heat. Do you know the BTU of your furnace?

  12. #12
    Join Date
    Sep 2012
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    373
    The furnace is 45,000 BTU input on first stage and 66,000 BTU input on high stage. That's what the service tech said when he came out a few weeks ago for our annual heating inspection and tune-up. The furnace is matched up with a 2 ton Amana Distinctions (Goodman) Air Conditioner that was installed last April along with a new evaporator coil.

  13. #13
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,135
    45,000 should be plenty, doubt the 2nd stage will ever kick on.
    Does it 'feel' hot when it short cycles?

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