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  1. #1
    Join Date
    Jan 2008
    Location
    Central Ohio
    Posts
    13

    heat pump vs propane how to compare?

    how do I go about comparing apples to apples for btu. I assume the hp btu is going to differ depending on temp. i know propane is about 91,500 btu per gallon. how do i know how many kwh i am using or need when I run the hp? just trying to get the best bang for my buck!! thanks for all the advice given so far. chris

  2. #2
    Join Date
    Jan 2007
    Location
    in my lumpy chair
    Posts
    1,951
    depends on the area your living in, cold climate, mild climate, or warm.

    you may wont to look into a duel fuel.
    I dont warranty Tinkeritus

  3. #3
    Join Date
    Jan 2008
    Location
    Central Ohio
    Posts
    13
    I live in ohio and got a 75000 btu propane rheem furnace. and a weather king 13 seer heat pump. just trying to see what way is cheaper. I am just realling wanting to know how I can calculate it out. like it takes xxx amount of electricity for the hp to run multiply that by my kwh rate and compare with propane. This is my second year running this system. last year i went through 300 gal of propane heating a 1684 sqft energy star house with electric bill in the hi 100's to low 200 dollar mark for the winter months. thanks chris

  4. #4
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    Quote Originally Posted by badboti View Post
    how do I go about comparing apples to apples for btu. I assume the hp btu is going to differ depending on temp. i know propane is about 91,500 btu per gallon. how do i know how many kwh i am using or need when I run the hp? just trying to get the best bang for my buck!! thanks for all the advice given so far. chris
    Well you've alread got a dual fuel system, right? So you're seeking the COP of the heat pump. Knowing the cost of electricity in your Ohio area, you can use the performance numbers of your 13-SEER HP to determine the cost of operation of the HP vs the LP gas furnace. However, as a general rule of thumb, the HP is probably sized for cooling, not heating because you've got the gas furnace. So that means the HP will run out of capacity probably somewhere in the 30-degree temperature range. Personally, I'd set the HP to turn off at 38-40G and switch it over to the LP gas. That's where you'll get the best bang for your buck and still be comfortable.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,314
    Do you have the install manuals for your heat pump.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  6. #6
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    238
    find the COP of you system and use this:

    http://www.ag.ndsu.edu/pubs/ageng/structu/ae1015a.pdf

  7. #7
    Join Date
    Jan 2008
    Location
    Central Ohio
    Posts
    13
    yes i have the install manual

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,314
    Not what I meant to ask you, lol, sory about that. I've been up to long.
    Can ou post the mod number of both the OD and your coil.

    One of us may have the specs on it, and be able to post back the performance for it.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Jan 2008
    Location
    Central Ohio
    Posts
    13
    hp model number 13PJA30A01 coil on top of furnace model number RCFA-HM3617AC thanks for all the help

  10. #10
    Join Date
    Mar 2006
    Location
    The South
    Posts
    2,213
    Quote Originally Posted by badboti View Post
    how do I go about comparing apples to apples for btu. I assume the hp btu is going to differ depending on temp. i know propane is about 91,500 btu per gallon. how do i know how many kwh i am using or need when I run the hp? just trying to get the best bang for my buck!! thanks for all the advice given so far. chris
    Chris

    Oil and propane are two of the most expensive fuels for winter heating. If you know your electric rate ,propane cost/gal, and efficiencies, then you can make an intelligent comparison. Here is a fuel calculator that will provide a close estimate.

    IMO
    Good Luck!

    http://www.warmair.com/html/fuel_cost_comparisons.htm

  11. #11
    Join Date
    Jan 2009
    Posts
    20
    Quote Originally Posted by badboti View Post
    I live in ohio and got a 75000 btu propane rheem furnace. and a weather king 13 seer heat pump. just trying to see what way is cheaper. I am just realling wanting to know how I can calculate it out. like it takes xxx amount of electricity for the hp to run multiply that by my kwh rate and compare with propane. This is my second year running this system. last year i went through 300 gal of propane heating a 1684 sqft energy star house with electric bill in the hi 100's to low 200 dollar mark for the winter months. thanks chris
    You didn't give the efficiency of your propane furnace. I'll assume 80%,

    300gal*91.5Mbtu*.8 = 22,000 Mbtu of heating.

    You didn't give the tonnage of your heat pump. I'll assume 4 ton builder grade HP at 8.3HSPF. at 17 degrees, it will produce 26.7 Mbtu/hour.

    so 22,000/26.7 = 824 hours of heat pump. At 3.13kw/hour, thats 2580kwh.

    If you're paying .11 a kwh, that's $284 of electricity for the heat pump AT 17 DEGREES. The Propane is costing you $600 to $900.

    In other words, if you're looking at where to put your lockouts from economics, that point probably doesn't exist. Just go with a droop style electronic thermostat that will turn the furnace on when the heat pump can no longer keep up with building heat loss. Most people use the propane furnace backup for comfort, not economy. In that scenario, just set it where you're comfortable.

  12. #12
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,586
    I live in Texas, lots more cooling than heating. I alway survey my customers when they have propane or a heat pump with electric heat. We don't many dual fuel systems, maybe 5-10 a year. My customers pay anywhere between 12-15 cents per kwh and $2.50-$3.00 lb for propane. My customers that have a heat pump with electic backup have lower bills overall than straight propane customers. Our dual fuel people run right at heat pump + a little more when its colder. The big thing is spending several hundred dollars to fill that tank in your yard every few weeks. I don't think most like the sticker shock to fill it.
    I like DIY'ers. They pay better to fix.

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