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  1. #53
    OK, I agree "not everyone" based on the application but it certianly has its place.

  2. #54
    Join Date
    Mar 2008
    Location
    Jackson, NJ
    Posts
    176
    Quote Originally Posted by platchford View Post
    I understand what you are saying... but if the furnaces are running properly the oil does cost less (per BTU) at the price you previously listed... albeit not much.
    LP - 80% efficient - 29,727 BTU per $1
    Oil - 80% efficient - 30,352 BTU per $1
    The website I use for conversions lists 95000 BTUs per gallon of LP compared to 91,000 BTUs listed by someone else.

    Anyway, in my experience, people who live in farm houses generally don't keep their homes as warm as those who live in townhouses. I still think part of the issue is people look at how much they pay per gallon and don't take into account the efficiency or the BTUs produced.
    This is from the DOE:

    http://www.eere.energy.gov/consumer/.../mytopic=12330

    It shows:
    Fuel Oil (No. 2) 140,000/gallon
    Electricity 3,412/kWh
    Natural Gas 1,025,000/thousand cubic feet
    Propane 91,330/gallon
    Wood (air dried)* 20,000,000/cord or 8,000/pound
    Pellets (for pellet stoves; premium) 16,500,000/ton

    Actually gimps LPG output .... which if true stinks b/c that's my backup fuel.

  3. #55
    Join Date
    Apr 2008
    Posts
    14
    Quote Originally Posted by gary_g View Post
    From the Product Specs for my new Goodman heat pump, 3 tons:

    Outside Temp----------COP

    65---------------------4.37
    55---------------------4.04
    45---------------------3.64
    35---------------------3.25
    25---------------------2.82
    15---------------------2.46
    5----------------------2.06
    So I ran the numbers, and based off these specs, and what I'm paying for gas and electric, a heat pump is going to be more efficient than my 80% gas furnace pretty much all of the time (down to around 16F). Heck, its even going to be more efficient than a 96% furnace down to around 29 degrees. Is this a particularly efficient heat pump, or are these fairly average numbers?

    If this is true, how come almost none of the people in this area (NJ) have heat pumps? And how come none of the four contractors I got quotes from suggested a heat pump?

    The numbers for those that are interested:

    Code:
    Cost of 1 million btus:
    
    Natural gas at $1.45 per therm, 80% efficient
    (1,000,000 / 103,000) x 1.45 / .8
    = $17.60
    
    Electricity at 15 cents per kw-hr, outdoor temp = 16F (COP = 2.5)
    (1,000,000 / 3413) x .15 / 2.5
    = $17.59

  4. #56
    Join Date
    Mar 2008
    Location
    Jackson, NJ
    Posts
    176
    I'd like to know what I'm missing too. I mean, I never heard of a heat pump until I looked for homes in PA (Natural Gas lines are not that prevelant out there).

    Heat pumps look like a can't lose technology; so what's the catch? Because of this forum I'm having a heat pump installed in my home in PA (duel fuel - propane backup), but if there is a catch please let it be known !

  5. #57
    Join Date
    Mar 2006
    Location
    The South
    Posts
    2,238
    jopopsy

    no catch!

    electric HP properly sized vs propane gas furnace is really a no brainer.

    I suggest a HP that has electronic demand defrost vs timed defrost.

    Have your ductwork inspected.

    Crunch the numbers on attached fuel comparison calculator. You will smile at the projected savings!

    IMO


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

  6. #58
    Join Date
    Mar 2008
    Location
    Jackson, NJ
    Posts
    176
    Quote Originally Posted by tigerdunes View Post
    jopopsy

    no catch!

    electric HP properly sized vs propane gas furnace is really a no brainer.

    I suggest a HP that has electronic demand defrost vs timed defrost.

    Have your ductwork inspected.

    Crunch the numbers on attached fuel comparison calculator. You will smile at the projected savings!

    IMO


    http://www.warmair.com/html/fuel_cost_comparisons.htm
    Oh, I already did the numbers that's why I'm full steam ahead. Seems so black and white I just don't understand why more folks aren't doing this.

  7. #59
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by jaguar36 View Post
    Code:
    Cost of 1 million btus:
    
    Natural gas at $1.45 per therm, 80% efficient
    (1,000,000 / 103,000) x 1.45 / .8
    = $17.60
    
    Electricity at 15 cents per kw-hr, outdoor temp = 16F (COP = 2.5)
    (1,000,000 / 3413) x .15 / 2.5
    = $17.59
    Jag:

    FYI, below the balance point of the home (anywhere from 32F to 25F outside temp), the heat pump will not be able to heat the home by itself, and supplimental heat (from the propane furnace) is needed. This doesn't show up in your calc, and you should be aware of this additional cost.

    Take care.

  8. #60
    Join Date
    Nov 2006
    Location
    Montana
    Posts
    134
    Quote Originally Posted by jaguar36 View Post
    So I ran the numbers, and based off these specs, and what I'm paying for gas and electric, a heat pump is going to be more efficient than my 80% gas furnace pretty much all of the time (down to around 16F). Heck, its even going to be more efficient than a 96% furnace down to around 29 degrees. Is this a particularly efficient heat pump, or are these fairly average numbers?

    If this is true, how come almost none of the people in this area (NJ) have heat pumps? And how come none of the four contractors I got quotes from suggested a heat pump?

    The numbers for those that are interested:

    Code:
    Cost of 1 million btus:
    
    Natural gas at $1.45 per therm, 80% efficient
    (1,000,000 / 103,000) x 1.45 / .8
    = $17.60
    
    Electricity at 15 cents per kw-hr, outdoor temp = 16F (COP = 2.5)
    (1,000,000 / 3413) x .15 / 2.5
    = $17.59
    So, how many BTUs is your HP supplying at 16 degrees? It may look like the HP is more efficient at this temperature but if it can't keep up with the heat loss of your home it will actually be more expensive to run. Eventually, your thermostat will bring on your propane furnace but only after money has been wasted.

    You MUST know the thermal balance point where it becomes more economical to run the propane furnace.

  9. #61
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by Jopopsy View Post
    Heat pumps look like a can't lose technology; so what's the catch? Because of this forum I'm having a heat pump installed in my home in PA (duel fuel - propane backup), but if there is a catch please let it be known !
    No catch, but a few things you should know:
    - Heat pumps produce 95-degree air at 32F outside. As the outdoor temp drops the temp of the air produced by the heat pump also drops. Furnaces put out "hot" air; 120F or so.
    - In brutal cold temps, a heat pump may run constantly if there is no dual-fuel system (all-electric home).
    - Heat pumps have a shorter life expectancy than straight a/c units because they run during all 4 seasons.

    Take care.

  10. #62
    Join Date
    Apr 2008
    Posts
    14
    Quote Originally Posted by shodinjido View Post
    So, how many BTUs is your HP supplying at 16 degrees?
    This is an excellent question, how do you find the anwser to it? I can't seem to find any real specs for the heat pumps on Trane or Lennox's website, Is it not published, or is it just hidden away somewhere?

    Quote Originally Posted by shodinjido View Post
    Eventually, your thermostat will bring on your propane furnace but only after money has been wasted.
    The money is never wasted, as long as the heat pump is more efficient than the furnace. It may become a comfort issue if the temp drops to low before the furnace comes on, but no money would be wasted.

    ohh and, despite some folks trying to jack my thread I have natural gas, not propane.

  11. #63
    Join Date
    Nov 2006
    Location
    Montana
    Posts
    134
    Quote Originally Posted by jaguar36 View Post
    This is an excellent question, how do you find the anwser to it? I can't seem to find any real specs for the heat pumps on Trane or Lennox's website, Is it not published, or is it just hidden away somewhere?



    The money is never wasted, as long as the heat pump is more efficient than the furnace. It may become a comfort issue if the temp drops to low before the furnace comes on, but no money would be wasted.

    ohh and, despite some folks trying to jack my thread I have natural gas, not propane.
    Money is wasted because the power that you are feeding into the condenser isn't supplying the required heat for the home. When your furnace eventually comes on, it has to make up for the drop in temperature that your HP caused thereby having to use more fuel than previously needed.

    For example, if you start your car and let it idle for 20 minutes before you leave, have you wasted gas? Your car is running but not getting anywhere.

    You can figure heat output using Input Watts and the COP from manufacturers data charts (blower watts is also a factor )

  12. #64
    Join Date
    Apr 2008
    Posts
    14
    No the condenser may not be providing all of the required heat, but it is still providing some heat, and that heat is being provided more efficiently than would be provided by the furnace. Its not being wasted, its just not sufficient to keep the house at the proper temperature. Had the heat pump not been running the house would be colder than it is if the heat pump is running. The heat pump never causes a drop in temperature, it is just unable to complete halt the drop.

    Your analogy of a car running idle is not correct, as when the car is idle, it is not providing any forward motion, while the heat pump is still providing heat.

    Where can I find the manufactures data charts?

  13. #65
    Join Date
    Jan 2008
    Location
    Wisconsin
    Posts
    1,125
    Quote Originally Posted by platchford View Post
    I understand what you are saying... but if the furnaces are running properly the oil does cost less (per BTU) at the price you previously listed... albeit not much.
    LP - 80% efficient - 29,727 BTU per $1
    Oil - 80% efficient - 30,352 BTU per $1
    The website I use for conversions lists 95000 BTUs per gallon of LP compared to 91,000 BTUs listed by someone else.

    Anyway, in my experience, people who live in farm houses generally don't keep their homes as warm as those who live in townhouses. I still think part of the issue is people look at how much they pay per gallon and don't take into account the efficiency or the BTUs produced.
    That's what I started thinking, those old farmers simply set the thermostat lower. And I suppose different blends of LP put out different BTUs. Maybe since heat is needed 6-7 months out of the year here, we get some hotter burning stuff. Not sure if there's a difference in blends. I have oil heat in my home, and seriously considered switching to natural gas when I replaced my furnace in December. Gas company wanted to much to run the line in though unless I would have installed a natural gas water heater. With the heat pump I just put in, I should save a quite a bit next winter.

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