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  1. #1

    Heat Pump VS Electric Heater?

    Hi guys, I have a very important question for you.

    Okay, so my gf's mom has a heat pump (it's like 2yrs old only).

    Now.. instead of leaving the heat on all the time at a low setting at the least in winter, she shuts it OFF completely most of the time, and always at night, and instead uses those little electric wall plug in heaters in 2 rooms (her mom and her daughters room).

    My question is, which one will cost more money in the long run? She is trying to save money, but is what she is doing really truly cost efficient or is it perhaps costing her more, OR is it about the same?

    It gets soo cold at night throughout the house when you goto the bathroom you can feel your bones freeze practically.. yet she thinks she is saving so much from this so she does it.

    I'd love to hear what you guys have to say about this.

    P.S the heater in question that she uses resembles this kind of thing: http://www.canadiantire.ca/AST/brows....jsp?locale=en

    It's a little portable heater that you plug into the wall.

    She uses 2 of them that will stay on all night(and day if she didn't put the heat pump on) in different rooms
    Last edited by Morozevich; 12-11-2010 at 03:57 AM.

  2. #2
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    Electricity used by plug in electric heaters over night and aux heat each morning as the heatpump recovers theoretically should completely offset the savings.

    Air source heatpumps provide 2-3 units of heat for every unit of energy consumed (once the aux heat is taken into consideration the ratio could be 1.5:1), so they are inherently more efficient than plug in space heaters. (not to mention, heaters pose an extreme fire hazard - overloaded circuits, worn cords, etc.)

    Set it and forget it. (or use a programmable t-stat and reduce the temp by 1-2 degrees MAX at night)
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  3. #3
    Quote Originally Posted by amd View Post
    Electricity used by plug in electric heaters over night and aux heat each morning as the heatpump recovers theoretically should completely offset the savings.

    Air source heatpumps provide 2-3 units of heat for every unit of energy consumed (once the aux heat is taken into consideration the ratio could be 1.5:1), so they are inherently more efficient than plug in space heaters. (not to mention, heaters pose an extreme fire hazard - overloaded circuits, worn cords, etc.)

    Set it and forget it. (or use a programmable t-stat and reduce the temp by 1-2 degrees MAX at night)
    This is exactly what my father suggested (he's a plumber, but he does heating, natural gas, etc too)

    Thanks

  4. #4
    Join Date
    Apr 2002
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    Omaha, NE
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    It would be easy enough to figure out which method is more economical by recording the electrical power usage using the watt-hour meter on the side of the residence. Take a start reading on the meter and run the heat pump normally for 24 hours. Then take another reading and figure how many kilo-watt hours were consumed. Then do it again using her method of shutting off the heat pump and using the space heaters. As long as the other electrical usage in the home is roughly the same, it will give you an idea of the cost difference, and whether making everybody miserable with a cold house is really saving any money.
    B.O. = B.S.

  5. #5
    My heat pump is on a subpanel with a dedicated HVAC meter. Just to give you a rough idea of wattage...

    An electric space heater is typically 1500 watts. Some will have a lower wattage setting too (ours is 900W). This is enough for one room.

    Our Hallowell heat pump uses 1500 watts on stage 1, and 2500 watts on stage 2. That's to heat the whole house. I don't know if this is typical of other heat pumps or not, but it will give you an idea.

    Of course, you'll need to factor in the duty cycle of each method of heat - the heat pump will not run 100% of the time. Perhaps an electric space heater on a low setting would run all the time, but you'd need to multiply that by each room you're heating.

    - Chris

  6. #6
    Join Date
    Dec 2010
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    Eaton Rapids, Mi
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    Quote Originally Posted by chrispitude View Post
    the heat pump will not run 100% of the time.
    a heat pump won't need to run all the time, unless it is at or below balance point. it is possible for a heat pump to run constantly for quite some time with no issues, though.

    all in all, consider the COP rating of the heat pump. even a marginally efficent heat pump will have a COP of at least 3 above balance point.

    COP means coefficent of performance.. in other words, how many watts of heat do i get out for every watt in. That means that before balance point (essentially, before the electric strip heat kicks in to supplement the heat pump) for every watt in you get 3 watts of heating out. 3 times that of any electric heat, where the COP is 1. (1 watt in gives 1 watt out)

  7. #7
    Join Date
    Nov 2007
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    maryland
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    17
    watch the meter for the first hour when she turns the heat pump back on boy will she be surprised

  8. #8
    I was thinking about that as well... If she does an A/B experiment, she should be aware that the heat pump will have to heat the rest of the house back up that was not being heated as space heates. Once that's done (perhaps give it a day), then she should measure the steady-state usage from the heat pump.

  9. #9
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    Programmable t-stats and fossil fuel fired/electric resistance heaters mix. (no heatpump involved)

    Bringing the temperature back up in itself isn't a issue; the only problem is that heatpumps don't have the capacity to do so without very expensive supplemental heat.
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  10. #10
    Join Date
    Mar 2001
    Posts
    1,516
    Have done a lot of retrofit electric forced air to Heat pump installs. When first installing them in this area, I would tell potential customers the savings in their electical bills would average 30%. Been in this area since 96. Have never had to eat my words, and the followup statistics are closer to 40%, not taking price increases of electricity into consideration. I used to sell night set back thermostats with every system, but found that most of my customers (elderly retirees) were not happy with them. They were intimidated by them or confused about how they operate. I now sell them an auto changeover manual stat, tell them to set it and forget it. The only complaint I get are complaints of air coming out of registers in cold weather is not the nice hot air they experienced with forced air electric heat, or their gas and or oil heat that they had when they lived in the city, before they moved here to the beach.
    A lot of us "older" folks are used to sleeping in a cold bedroom. I tell them to close the bedroom door, and open a window to get the benefits of cool air for sleeping, but let the rest of the house remain at comfortable levels. The thermostat senses the temperature or the hallway or living room, where they are typically installed, and not the temperature in the colder bedroom. In the morning, they wake to a warm house, and only have the bedroom to reheat, after closing the window. Saves them money and keeps the aux heat off.
    One way to outthink people is to make them think you think. They'll think you're not really thinking what you're trying to get them to think you think...........

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