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  1. #1

    What is more effecient a 15 seers A/c or a 15 Seers Heat pump?

    What would be more efficient if I had both electric and natural gas at my property for heating and cooling a 1300 square foot house a normal 15 seer A/C system or a 15 Seer Heat Pump. My understanding is that a HP only is cheaper to run in heating mode and want really save me any money in cool mode. Because in the short mild winter times, I can just run a blower motor and use the furnace for heat. Does that make sense or am I totally off.
    Thank you for sharing.

  2. #2
    Join Date
    Dec 2010
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    The Quad-Cities area (midwest).
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    Quote Originally Posted by AUSTINTXAC View Post
    What would be more efficient if I had both electric and natural gas at my property for heating and cooling a 1300 square foot house a normal 15 seer A/C system or a 15 Seer Heat Pump. My understanding is that a HP only is cheaper to run in heating mode and want really save me any money in cool mode. Because in the short mild winter times, I can just run a blower motor and use the furnace for heat. Does that make sense or am I totally off.
    Thank you for sharing.
    Seer is like MPG. 15 SEER is equal to another 15 SEER (assuming the equipment is equal in size). You're right in that the HP is more efficient (maybe) overall because it'll heat as well as cool.

    It just depends on your natural gas prices verse your electric rates. A good contractor should have the tools (computer program) available to (quickly) show you the savings no matter what the equipment is or the fuel it uses.

    I could compare (in less than a minute) 4 different combinations of equipment and show the operating costs of each system. You should be getting that information to help you make an intelligent decision.
    Last edited by George2; 05-01-2013 at 01:48 PM. Reason: addition thought added

  3. #3
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,483
    Both AC and HP will have the same cooling efficiency if both are rated 15 SEER. At our home the electric rates have increased to the point where I turn the HP off and use just the gas furnace for heat. You're correct in your interpretation!

  4. #4
    Join Date
    Jan 2009
    Location
    Keokuk, IA
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    5,520
    Keep in mind, ther are "nominal" ratings, and ther are actual AHRI certified matched ratings. Even then, the operating conditions of those ratings, may not be how you actually operate your equipment. But like vehcile MPG, it's a matter of comparison to other vehciles, not nessesarily a gurantee of you actual performance.

    With dual fuel, you have to consider your electric and gas rates and if you have a 95%+ furnace or a 80% furnace. A heat pump will also provide an additonal lower stage of heat so you get longer run time sand more even tempratures in your home on mild days, where a furnace would normally short cycle. IN mild climates the furnaces are almost always oversized. In a small home like yours they probably don't make a furnace small enough. The industry actually could use a 15 and 30k BTU model furnace for some situations. Especially upstairs units.

  5. #5
    Join Date
    Jul 2006
    Location
    Virginia
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    4,619
    if you get a 60000 btu 2 stage furnace it will run on 1stage most of the time .also if you are in Austin Gas is pretty cheap
    We really need change now

  6. #6
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,272
    http://www.climate-zone.com/climate/.../texas/austin/

    What is more cost effective?

    EXAMPLE
    Electric heat pump unless Natural Gas < $0.70 per therm

    Define _____ therm
    100,000 _____ BTU
    0.85 _____ Efficiency
    $0.70 _____ $/ THERM
    $0.824 _____ Cost per 100,000 BTU
    _____
    3412 _____ BTU/ Kw
    29.308 _____ kw/ Therm
    $0.080 _____ Cost / kw
    2.9 _____ COP
    $0.0276 _____ Effective $ / kW
    $0.809 _____ Effective $ / 100,000 BTU

    You ought to be able to heat your house for $90 per year with natural Gas compared to $84 with electricity / heat pump with annual average COP of 3.2.
    DIFFERENCE ... one Starbucks cup of coffee per year
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  7. #7
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,483
    As Dan mentioned, very little cost savings with dual fuel right now with Nat. gas prices. Another consideration is the shortened life of the heat pump compared to just an AC unit. It runs twice as much and will therefore have a shorter life along with more break downs.

  8. #8
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,272
    Quote Originally Posted by dan sw fl View Post
    http://www.climate-zone.com/climate/.../texas/austin/

    What is more cost effective?

    EXAMPLE
    Electric heat pump unless Natural Gas < $0.70 per therm

    Define _____ therm
    100,000 _____ BTU
    0.85 _____ Efficiency
    $0.70 _____ $/ THERM
    $0.824 _____ Cost per 100,000 BTU
    _____
    3412 _____ BTU/ Kw
    29.308 _____ kw/ Therm
    $0.080 _____ Cost / kw
    2.9 _____ COP
    $0.0276 _____ Effective $ / kW
    $0.809 _____ Effective $ / 100,000 BTU

    You ought to be able to heat your house for $90 per year with natural Gas compared to $84 with electricity / heat pump with annual average COP of 3.2.
    DIFFERENCE ... one Starbucks cup of coffee per year
    http://www.eia.gov/dnav/ng/NG_PRI_SU...PRS_DMCF_M.htm

    Apparently, Texas is closer to $0.85 / therm based on EIA info
    or 20% higher than noted above.
    So Natural Gas $0.98 / Therm
    vs. Heat Pump $0.81 / Therm equivalent

    So you can use heat pump and
    buy 4 Starbucks coffees per Year.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

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