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  1. #1
    Join Date
    Jan 2010
    Posts
    5

    Ancient electric furnace

    I'll try to keep this short.

    I have an 1000 sf 2nd floor condo in a 3 story all-brick building with concrete floors. I have a Carrier Day and Night electric furnace/AC inside a utility closet (from 1978 - original to the house) and a fairly new 10 seer compressor in an external wall.

    The house is well insulated except for a few drafty windows which I plan on replacing. When the outside temp is above freezing, the heat rarely runs at all. If the temp is below 30 as we've had in NYC for the last month, the heat will run in spurts of 5 minutes on, 10 off, 5 on etc.

    I also haven't had a chance to have an HVAC tech look at the unit since I moved in due to time and $ issues, I've just been running it as-is. I plan on getting it looked at and cleaned out in a month.

    I know heat pumps are highly recommended, but would the high cost of installation pay off in my situation? Or am I better off keeping my current one running the best I can until it dies?

    For comparison sake, my electrical usage has been:

    - December 2100 kwh ($390)
    - October 853 kwh ($185) - temps were very mild that month
    - July 1103 kwh ($266)

  2. #2
    Join Date
    Apr 2005
    Posts
    412
    heat pump would deff pay off in your situation. Go with min 13seer and you will cut that bill alot, it should pay for itself.
    Jason J Saylor
    Pinellas County Schools
    HVAC Tech
    Pinellas County Florida

    "You will encounter many distractions and many temptations to put your goals aside: The security of a job, a wife who wants kids, Whatever. But if you hang in there, always following your vision, I have no doubt you will succeed.
    Larry Flynt quote

  3. #3
    Join Date
    Mar 2004
    Location
    SE Michigan
    Posts
    17,600
    I thought you were going to show us a cave painting of a furnace.
    "The road to Hell is paved with progressive policies."

  4. #4
    Join Date
    Jan 2010
    Posts
    5
    Quote Originally Posted by coolwhip View Post
    I thought you were going to show us a cave painting of a furnace.
    I am quite proficient at mspaint, I can whip one up for you if you really want, lol

  5. #5
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    20,270
    Definitely do the HP...

    Above freezing (and even a few D below freezing), the HP will be less expensive to run than elec strip heat.

    Be sure to get a reputable dealer to do the install... Also: Do the windows FIRST! The amount of heat (size of system) will change... as in potentially smaller. Be sure to point out to the installing contractor that you did the windows.
    GA-HVAC-Tech

    Galatians 2:20-21; Colossians 1: 21-22 & 26-27; 3:1-4; Romans Ch's 5-6-7-8

    2 Chronicles 7:14

    Quality work at a fair price with excellent customer service.

  6. #6
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by moocat View Post
    I know heat pumps are highly recommended, but would the high cost of installation pay off in my situation? Or am I better off keeping my current one running the best I can until it dies?
    Depending on ambient temps, a heat pump can provide heat from 200% to 400% cheaper than straight electric resistance heat.

    And if you consider an increase in efficiency from 10 SEER to 14 SEER, you'll save a minumum of 20% off of your cost to run the a/c in the summer.

    Take care.

  7. #7
    Join Date
    Jan 2010
    Posts
    5
    According to the US Dept of Energy:

    When outdoor temperatures fall below 40F, a less-efficient panel of electric resistance coils, similar to those in your toaster, kicks in to provide indoor heating. This is why air-source heat pumps aren't always very efficient for heating in areas with cold winters.

    Given the fact that my heat hardly runs when the outside temp is 40, would it still be a wise choice?

    Can a heat pump even be installed with a setup like mine? (indoor furnace, small outdoor condenser)

    Not arguing, just trying to make sure I don't spend more than I have to.

  8. #8
    Join Date
    Sep 2005
    Location
    Atlanta GA area
    Posts
    20,270
    Quote Originally Posted by moocat View Post
    According to the US Dept of Energy:

    When outdoor temperatures fall below 40F, a less-efficient panel of electric resistance coils, similar to those in your toaster, kicks in to provide indoor heating. This is why air-source heat pumps aren't always very efficient for heating in areas with cold winters.

    Given the fact that my heat hardly runs when the outside temp is 40, would it still be a wise choice?

    Can a heat pump even be installed with a setup like mine? (indoor furnace, small outdoor condenser)

    Not arguing, just trying to make sure I don't spend more than I have to.
    That is not an accurate statement. As usual, the government is spreading in-accurate information. First, the elec heat starts ONLY when the HP cannot keep up. This happens when the thermostat drops 3-5* below setpoint (as in the HP is not capable of keeping the home area warm). There is a measurement called COP that rates the ability of the HP to gather heat. The lower the temps go outside, the lower the COP. When the HP reaches a COP of 1.0, then it is no longer more efficient (less cost) to run. My HP at my home is still doing a COP in the low 2.x when it is in the mid 20's outside... some of the newer induction rotary drive HP's have a COP in the mid 2.x's down into the single digits temps outside...

    So no, that govewrnment statement, as usual, is wrong. In defense of the government... it is probably a decade or more out of date.
    GA-HVAC-Tech

    Galatians 2:20-21; Colossians 1: 21-22 & 26-27; 3:1-4; Romans Ch's 5-6-7-8

    2 Chronicles 7:14

    Quality work at a fair price with excellent customer service.

  9. #9
    Join Date
    Apr 2009
    Posts
    523
    This is an upgrade you would immediately notice on your utility bills.

  10. #10
    Join Date
    Nov 2008
    Posts
    1,673
    Quote Originally Posted by moocat View Post
    I know heat pumps are highly recommended, but would the high cost of installation pay off in my situation? Or am I better off keeping my current one running the best I can until it dies?
    The initial cost of your furnace divided by its age gives you the cost per year of running your current furnace.

    You have an even chance of getting 46 years out of that furnace so the question becomes,

    Which is a better choice within this 14 year time frame?

    I'd research the winter month HDDs for your area for the previous 14 years to predict how much each choice will cost over the next 14 years.
    Global warming over this period is probably negligible but other things may cause an upward or downward trend.

    http://www.degreedays.net/

  11. #11
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by moocat View Post
    According to the US Dept of Energy:

    When outdoor temperatures fall below 40F, a less-efficient panel of electric resistance coils, similar to those in your toaster, kicks in to provide indoor heating. This is why air-source heat pumps aren't always very efficient for heating in areas with cold winters.

    Given the fact that my heat hardly runs when the outside temp is 40, would it still be a wise choice?

    Can a heat pump even be installed with a setup like mine? (indoor furnace, small outdoor condenser)

    Not arguing, just trying to make sure I don't spend more than I have to.
    First of all, electric resistance heat is 100% efficient at all ambient temps. It is expensive to run, but it is always 100% efficient. They are confusing efficiency with operating costs. Not the same thing.

    Operating data for my 14 SEER, 9 HSPF, heat pump:

    Ambient
    temp----------C.O.P.

    55F-----------4.04
    45F-----------3.64
    35F-----------3.25
    25F-----------2.82
    15F-----------2.46

    At 55F ambient, my heat pump is 404% cheaper to run than straight electric ressistance heat. Even at 15F ambient, it is still 246% cheaper to run than straight electric.

    Take care.

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