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  1. #1

    Benefits/drawbacks of oversizing heatpump Trane XL18I

    Most HVAC companies recommend a 3 ton heat pump for my house. If I went to a 4 ton unit - does the winter temperature of the balance point lower (any idea on by how much it will lower, 2000sqft house in PA)? I know my AC will short cycle - I do not care about this, I'm looking for the most efficiency in the winter months as heat is on for more months than AC. The unit will be a dual stage Trane XL18I. Are there any other drawbacks of over-sizing a heat pump? Thanks.

  2. #2
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
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    Quote Originally Posted by racinkart2 View Post
    Most HVAC companies recommend a 3 ton heat pump for my house. If I went to a 4 ton unit - does the winter temperature of the balance point lower (any idea on by how much it will lower, 2000sqft house in PA)? I know my AC will short cycle - I do not care about this, I'm looking for the most efficiency in the winter months as heat is on for more months than AC. The unit will be a dual stage Trane XL18I. Are there any other drawbacks of over-sizing a heat pump? Thanks.
    You'll get more heat from the larger HP. The balance point will be the same (I'm guessing) but you'll be using less back-up heat. The 2 stage operation will help during the A/C season. I'm assuming you'll be changing the furnace or the air handler (with a variable-speed blower) as well?

  3. #3
    Yes. I will be replacing the whole AC unit with a matching Trane heatpump & variable speed air handler as well. The existing heat is electric baseboards, I'd just like to use the heat pump as much as possible in the winter. Thanks for posting.

  4. #4
    Join Date
    Sep 2008
    Location
    Western PA
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    25,659

  5. #5
    Join Date
    Jan 2004
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    Lancaster PA
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    68,033
    Quote Originally Posted by George2 View Post
    You'll get more heat from the larger HP. The balance point will be the same (I'm guessing) but you'll be using less back-up heat. The 2 stage operation will help during the A/C season. I'm assuming you'll be changing the furnace or the air handler (with a variable-speed blower) as well?
    The balance point will be lower.
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  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,033
    Quote Originally Posted by racinkart2 View Post
    Yes. I will be replacing the whole AC unit with a matching Trane heatpump & variable speed air handler as well. The existing heat is electric baseboards, I'd just like to use the heat pump as much as possible in the winter. Thanks for posting.
    Don't forget. That there is a good chance that most of your duct work will need changed out. Along with additional supplies and return/returns added to move the additional air the 4 ton will need over a 3 ton.
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  7. #7
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
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    The low speed heat/cool air flow may be about right for your old ducts. High flow may be noisy. Like all a/c, you will need supplemental dehumidification to provide <50%RH throughout your home during low/no cooling loads and +60^F outdoor dew points. Prepare for 2-3 lbs. of dehumidification when the home is occupied and +60^F outdoor dew points. Locating a whole house 70 pint per day dehumidifier, an Ultra-Aire 70H in the basement alongside the heat pump would be the perfect combination for >50%RH throughout the home including the basement, regardless the cooling load or oversizing of the heat pump. This also provides <50%RH with the cooling off when the home is unoccupied and high outdoor dew points. This will be a big energy saver.
    Regards TB
    Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  8. #8
    Join Date
    Dec 2010
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    Quote Originally Posted by beenthere View Post
    Don't forget. That there is a good chance that most of your duct work will need changed out. Along with additional supplies and return/returns added to move the additional air the 4 ton will need over a 3 ton.
    Very good point. I had forgotten about that little issue.

  9. #9
    Join Date
    Sep 2009
    Location
    Arnold mo
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    You need to get an energy audit and find out if your home has a lot of air leakage and any insulation issues. Heat pumps are lousy at providing comfort in winter in a home with a lousy envelope.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  10. #10
    All the duct work will be updated to R8. There will be 1 additional return added and 1 supply added for the larger unit. When I look at the AHRI certificates, the 3 ton unit is rated at 22,200BTUH @ 17 degree's F, the 4 ton unit is rated at 29,800BTUH @ 17 degree's F, both for region IV. Do you think the 7600 extra BTU from the 4 ton justifies going with the larger unit?

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    If it gets your heating balance point to 25 or lower it is.

    Must be a big room that never heated or cooled right. That adding only one supply will gt you the proper air flow. 400 CFM additional supply to only one room?
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  12. #12
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
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    Quote Originally Posted by racinkart2 View Post
    All the duct work will be updated to R8. There will be 1 additional return added and 1 supply added for the larger unit. When I look at the AHRI certificates, the 3 ton unit is rated at 22,200BTUH @ 17 degree's F, the 4 ton unit is rated at 29,800BTUH @ 17 degree's F, both for region IV. Do you think the 7600 extra BTU from the 4 ton justifies going with the larger unit?
    As recommended have an energy audit performed and adjust the load to allow a smaller unit to be used and save money in utility bills and be comfortable.

  13. #13
    Join Date
    Aug 2012
    Location
    North Dakota
    Posts
    518
    what duct work comes with ele. base board why not install a gas \ propane furnace ? for your climate youll be happier$

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