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  1. #1
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    Default Heat pump undersized

    Inspecting a 1400 sq ft house today with a 2 ton heat pump. Heat pump had a difficult time heating the house. I jumped the thermostat to 73* not get a 100* surface temp out of the register vent (I usually set temp at 70* and get 100* surface temp to call it good. I know what the size tonnage should be (2.5) but, in TN we don't inspect the size as part of our inspection. How do state something in report without getting out of my inspector lane. ??

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  2. #2
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    Default Re: Heat pump undersized

    Quote Originally Posted by Sam Morris View Post
    Inspecting a 1400 sq ft house today with a 2 ton heat pump. Heat pump had a difficult time heating the house. I jumped the thermostat to 73* not get a 100* surface temp out of the register vent (I usually set temp at 70* and get 100* surface temp to call it good. I know what the size tonnage should be (2.5) but, in TN we don't inspect the size as part of our inspection. How do state something in report without getting out of my inspector lane. ??
    Sam,

    How about:

    "While calculating heating and cooling loads and sizing of heating and cooling equipment is beyond the scope of a home inspection, air temperatures at the interior registers indicate that this system is undersized and may not heat or cool the home adequately. I recommend evaluation of the heating/cooling system by a licensed heating contractor and corrections or replacement, as needed. "

    Department of Redundancy Department
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  3. #3
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    Default Re: Heat pump undersized

    Quote Originally Posted by Gunnar Alquist View Post
    Sam,

    How about:

    "While calculating heating and cooling loads and sizing of heating and cooling equipment is beyond the scope of a home inspection, air temperatures at the interior registers indicate that this system is undersized and may not heat or cool the home adequately. I recommend evaluation of the heating/cooling system by a licensed heating contractor and corrections or replacement, as needed. "
    Thank You, That's perfect


  4. #4
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    Default Re: Heat pump undersized

    Sam,
    First, the temperature you set the thermostat doesn't have anything to do with the air temperature. What matters is that the unit is calling for heat. The temperature is going to be the same at 73 or 80.
    Second, I wouldn't say anything about the unit being undersized as that doesn't seem to be the issue. The issue is the air temperatures did not get to 100 degrees. I would call for a licensed HVAC contractor to service and repair the unit to operate properly.

    I just inspected a home that was 3000 sqft and had a 4 ton unit. It worked great! Depends on Manual J calculations and those take into account the ceiling height, fenestration, insulation etc.


  5. #5
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    Default Re: Heat pump undersized

    Quote Originally Posted by Gunnar Alquist View Post
    "While calculating heating and cooling loads and sizing of heating and cooling equipment is beyond the scope of a home inspection, air temperatures at the interior registers indicate that this system is undersized and may not heat or cool the home adequately. I recommend evaluation of the heating/cooling system by a licensed heating contractor and corrections or replacement, as needed. "
    Quote Originally Posted by Gary Burnett View Post
    Sam,
    First, the temperature you set the thermostat doesn't have anything to do with the air temperature. What matters is that the unit is calling for heat. The temperature is going to be the same at 73 or 80.
    Second, I wouldn't say anything about the unit being undersized as that doesn't seem to be the issue. The issue is the air temperatures did not get to 100 degrees. I would call for a licensed HVAC contractor to service and repair the unit to operate properly.

    I just inspected a home that was 3000 sqft and had a 4 ton unit. It worked great! Depends on Manual J calculations and those take into account the ceiling height, fenestration, insulation etc.
    Sam,

    Gary has a point. While it might be a sizing issue, it could also be a dirty coil at the air handler, faulty reversing valve, whatever. It might be better to not make any comments judging sizing (other than to state that sizing is beyond the scope) and just state that you believe the temperature differential at the registers is inadequate to heat the home, then defer to a heating contractor.

    However, I disagree with Gary in the "service and repair the unit" statement. If it is undersized, then servicing or repairing the unit would not correct the problem. I would prefer a statement that does not allow the client to think that it just needs to be serviced or repaired. I would use wording like "service, repair or replacement, as needed" or possibly "any needed corrections". Something that is less likely to be misunderstood.

    Department of Redundancy Department
    http://www.FullCircleInspect.com/

  6. #6
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    Default Re: Heat pump undersized

    Sam,
    2 tons might be the correct size for 1 1400 SF house. A lot depends on the house itself, meaning windows (type and number), insulation, age of unit and SEER rating.

    Looking for 100 degrees is also not a good way to determine if its working properly.

    Was it running on heat pump mode only? Did you feel the refrigerant line to see if it was warm/hot to touch?
    Was it running on Aux heat mode?
    Did you try it on Emergency heat mode to determine if the heat strips were operating?

    Also saying its not heating the house properly also has variables. What was the house temperature when you got there? How long did you let the unit run? A heat pump putting out 90 degrees will heat a house fine if it runs long enough. Its been so cold here in East Tennessee that if the house was not occupied and the thermostat was set very low, it could take a very long time to bring it up to temperature.

    It could be the heat strips were not working properly.

    That said, I have a multi speed, multi stage heat pump at my house, and it rarely uses the heat strips because newer more efficient units can extract more heat out of the air than older lower SEER units.

    There is a lot more to it than setting the thermostat to 70 and expecting 100.


  7. #7
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    Default Re: Heat pump undersized

    Quote Originally Posted by Jack Feldmann View Post
    Sam,
    2 tons might be the correct size for 1 1400 SF house. A lot depends on the house itself, meaning windows (type and number), insulation, age of unit and SEER rating.

    Looking for 100 degrees is also not a good way to determine if its working properly.

    Was it running on heat pump mode only? Did you feel the refrigerant line to see if it was warm/hot to touch?
    Was it running on Aux heat mode?
    Did you try it on Emergency heat mode to determine if the heat strips were operating?

    Also saying its not heating the house properly also has variables. What was the house temperature when you got there? How long did you let the unit run? A heat pump putting out 90 degrees will heat a house fine if it runs long enough. Its been so cold here in East Tennessee that if the house was not occupied and the thermostat was set very low, it could take a very long time to bring it up to temperature.

    It could be the heat strips were not working properly.

    That said, I have a multi speed, multi stage heat pump at my house, and it rarely uses the heat strips because newer more efficient units can extract more heat out of the air than older lower SEER units.

    There is a lot more to it than setting the thermostat to 70 and expecting 100.
    The way I inspect houses has worked great for 14 yrs, but sometimes you run into those houses that you have questions about. The thermostat inside reading when I arrived was set to 70* (outside temp. was 30*) Oh, by the way the house had 3 contracts on the house prior to my arrival and the owner said his friend put the unit in last year. All week I have been checking heat pumps and none them gave me trouble heating like this one did. I ran the heat for 30 mins at 1 degree over the set temp. so to insure not to turn the aux. heat on. I tried for another 15 mins checking the register vent 4 ft away in the bedroom from the package unit outside and still could get the proper temp needed for me to call it good (house had double pane windows, 10" of Rockwool attic insulation) Unit was undersized for a 1464 sq ft house (2 ton) so I ended up calling out a licensed HVAC contractor.


  8. #8
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    Default Re: Heat pump undersized

    Quote Originally Posted by Sam Morris View Post
    The way I inspect houses has worked great for 14 yrs, but sometimes you run into those houses that you have questions about. The thermostat inside reading when I arrived was set to 70* (outside temp. was 30*) Oh, by the way the house had 3 contracts on the house prior to my arrival and the owner said his friend put the unit in last year. All week I have been checking heat pumps and none them gave me trouble heating like this one did. I ran the heat for 30 mins at 1 degree over the set temp. so to insure not to turn the aux. heat on. I tried for another 15 mins checking the register vent 4 ft away in the bedroom from the package unit outside and still could get the proper temp needed for me to call it good (house had double pane windows, 10" of Rockwool attic insulation) Unit was undersized for a 1464 sq ft house (2 ton) so I ended up calling out a licensed HVAC contractor.
    Thats only 732 sf per ton well within the normal range. Did you happen to look inside the unit? Was it icing up?
    Its one thing to call out something not working, its quite another to say its too small.


  9. #9
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    Default Re: Heat pump undersized

    I'm not sure about your climate but here we size heat pumps based on the cooling portion since we are predominantly a cooling climate. Supplemental heat is then added to meet extremes if needed.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

  10. #10
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    Default Re: Heat pump undersized

    Keep in mind that the code only requires the heating system to maintain 68?F ... not saying that is all I would want the heat set at in my house, and that heating ability is based on the climate set for the area, and (as we can all see) those climate conditions are changing.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  11. #11
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    Default Re: Heat pump undersized

    Quote Originally Posted by Gunnar Alquist View Post
    Sam,

    Gary has a point. While it might be a sizing issue, it could also be a dirty coil at the air handler, faulty reversing valve, whatever. It might be better to not make any comments judging sizing (other than to state that sizing is beyond the scope) and just state that you believe the temperature differential at the registers is inadequate to heat the home, then defer to a heating contractor.

    However, I disagree with Gary in the "service and repair the unit" statement. If it is undersized, then servicing or repairing the unit would not correct the problem. I would prefer a statement that does not allow the client to think that it just needs to be serviced or repaired. I would use wording like "service, repair or replacement, as needed" or possibly "any needed corrections". Something that is less likely to be misunderstood.
    I concur as this is well stated and adequately address the issue.


  12. #12
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    Default Re: Heat pump undersized

    Quote Originally Posted by Phil brody View Post
    I concur as this is well stated and adequately address the issue.
    Agree, with the additional comment that low discharge temp is not a sizing issue with matching units or self contained like this one. You could have a 1 ton unit in a 4,000 sf house and if the unit was functioning properly the discharge temp would still be pumping out adequate temp at rated O.A.T.. An undersized unit would not be able to bring the space temp up to set point but can still put out the correct discharge temp.

    Ken Amelin
    Cape Cod's Best Inspection Services
    www.midcapehomeinspection.com

  13. #13
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    St. George, UT
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    219

    Default Re: Heat pump undersized

    The setting at the thermostat (usually) does have a bearing on the output in a sense, but only if the Heat-Pump has an Electric Heat Strip (AUX heat) option installed. If in heat-Pump mode, you are normally going to get the 15-20 temp rise (some units you will see more like 30 deg rise or differential.)

    What you do is set the thermostat only 2-3 degrees above inside temp and *usually it will operate in heat-Pump only mode. You set it up 4 or more degrees above ambient inside and the AUX heat will come on (if so equipped). I really like the old mercury bulb/switch type, because you can actually see when the Aux mode kick in.

    * I say usually because some newer electronic thermostats seam to go strait to AUX-Heat when manually increasing the temp setting even if just 1-2 degrees, or if the outside temp is lower than about 40 degrees. What I have found is that the auto settings in the newer units are different depending on how they are programmed (Thermostat and or the unit itself). We do have a lot of heat-pumps where I am. I usually try to get a temp reading in heat-pump mode and then with Aux-heat operating.

    And as a side note: There is normally a label on the inside section of the heat-pump that will show the Aux-heat/ Heat Strip that can be installed and the HVAC installer is supposed to mark it, but I very seldom see this marked.


  14. #14
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    Default Re: Heat pump undersized

    Quote Originally Posted by Larry Morrison View Post
    And as a side note: There is normally a label on the inside section of the heat-pump that will show the Aux-heat/ Heat Strip that can be installed and the HVAC installer is supposed to mark it, but I very seldom see this marked.
    When I did AHJ code inspections, that was a very common inspection failure for most contractors for their first couple of inspection.

    That information, on the ones I saw, was on the nameplate label on the outside of the unit.

    Without it being marked, the inspector does not know what minimum size conductors are required or the maximum overcurrent protection size.

    The contractors would say 'All you had to do was call me.', to which I replied 'I don't have time to call you.' (that was my baited hook I dropped out there), to which they would say 'It doesn't take much time at all to call,' at which time I would reel them in after taking that bait and the proverbial hook, line, and sinker ... 'Takes even less time for you to mark the size ... as you are required to do.'

    Fling them up on the dock to flop around a bit before throwing them back in with 'You need to call it in for a reinspectiion.'

    Last edited by Jerry Peck; 03-12-2019 at 03:26 PM. Reason: Speelin' meant "reel" and it typed "feel" - corrected it
    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  15. #15
    Join Date
    Jul 2011
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    Central PA
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    Default Re: Heat pump undersized

    Quote Originally Posted by Sam Morris View Post
    Inspecting a 1400 sq ft house today with a 2 ton heat pump. Heat pump had a difficult time heating the house. I jumped the thermostat to 73* not get a 100* surface temp out of the register vent (I usually set temp at 70* and get 100* surface temp to call it good. I know what the size tonnage should be (2.5) but, in TN we don't inspect the size as part of our inspection. How do state something in report without getting out of my inspector lane. ??
    We have lots of heat pumps in my area (PA). Many modern homes that are 1,400 sq ft have 2 ton units around here. Depends what the tech found when he did a manual J. 2 ton may be fine for that home or maybe too small.. as home inspectors we don't calculate exact tonnage but I generally use an approx. 500~900 sq ft/ton as that puts me close to where we want to be. Normally I measure b/w 90 ~110 deg F output in either Heat or EMheat mode so it doesn't matter what you have the thermostat set up as long as it's a few degs higher than the room temp.

    If you weren't getting output temps that you expect (at least 90 degs F), then I'd write it up. Could be a dirty filter, air flow issue, or some other issue. Document it and refer it to a qualified HVAC tech.


  16. #16
    Join Date
    May 2010
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    Default Re: Heat pump undersized

    Quote Originally Posted by Jerry Peck View Post
    When I did AHJ code inspections, that was a very common inspection failure for most contractors for their first couple of inspection.

    That information, on the ones I saw, was on the nameplate label on the outside of the unit.

    Without it being marked, the inspector does not know what minimum size conductors are required or the maximum overcurrent protection size.

    The contractors would say 'All you had to do was call me.', to which I replied 'I don't have time to call you.' (that was my baited hook I dropped out there), to which they would say 'It doesn't take much time at all to call,' at which time I would reel them in after taking that bait and the proverbial hook, line, and sinker ... 'Takes even less time for you to mark the size ... as you are required to do.'

    Fling them up on the dock to flop around a bit before throwing them back in with 'You need to call it in for a reinspectiion.'
    So True! I'll bet I have only seen maybe six or seven of the labels marked out of the hundreds that I have seen over the course of almost ten years doing inspections. I will and have called this out when I do New Construction/11 month inspections. on older/existing homes it can just open a can of worms.


  17. #17
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    362

    Default Re: Heat pump undersized

    Quote Originally Posted by Jack Feldmann View Post
    Thats only 732 sf per ton well within the normal range. Did you happen to look inside the unit? Was it icing up?
    Its one thing to call out something not working, its quite another to say its too small.

    I tell my wife the same thing.


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