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We live in a house that has a heat pump system, for AC and heat, with a second-stage heating coil for aux/emergency heat. It frequently gets down to below 30 degrees in our climate, at which point the heat pump is essentially ineffective and the electric coils switch on.

That being the case, I'd like to set up space heaters in one or more rooms in our 2-story house, possibly a quartz infrared heater like you see on the market nowadays, to supplement our central heat and to get the heat where it needs to be. I hear a lot about how space heaters are a waste and don't save you any money/energy, but that seems to be a generalization, and I'd like to hear from someone who HAS used supplemental heat such as space heaters to keep their home warm without over-taxing the heat pump or using a huge amount of electricity.

Would a space heater help us in the winter months, or would it be wasteful?

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    When the heat pump is not running, I get a draft through the return duct. I found that turning off the heat pump and blocking the duct while using space heaters makes for a warmer house. Of douse, I'm talking about a small home with unused rooms closed off. Still waiting for the electric bill. Any thoughts? – user992 Dec 19 '13 at 14:40
  • @davefromPhilly Hi, and welcome to the site. Please can you copy & paste your question as a new question (using the "Ask Question" button in the top right of the screen)? Sorry we don't have the means to convert it into a question ourselves. – EnergyNumbers Dec 19 '13 at 20:01
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As I understand it, in the scenario that you describe, the heat pump is not doing anything useful, and the question simply boils down to "Is it best to use a resistive electric heater through a central heating system, or to use radiative (infra-red) heaters in the rooms that are occupied".

That's quite a simple one to answer: Either system is 100% efficient at converting electricity to heat, but the radiative heaters do it in the room where the heat is wanted, while the central system does it somewhere else and moves the heat to the rooms where it is wanted, losing some along the way. Therefore, individual heaters in the rooms to be warmed must be more efficient.

There are three important caveats here, though:

  1. If the heat pump is not totally ineffectual, but is still working with a reduced performance factor that is still >1, then using this with some "top-up" from the resistive coil may be the best option.
  2. If the central heating is needed for another purpose (e.g. hot water) then this may interact favourably with the heating.
  3. What is best in energy terms may not be best in economic terms, depending on your electricity tariff. For instance, it could be that the central heating's coil heater runs on a cheaper rate per unit of electricity than a heater plugged into a wall socket.
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Space heaters (yes, even those fancy quartz ones) use electric resistance to generate heat. If your home's HVAC system is switching to resistance heating when it's cold outside, replacing it with space heaters should, in an ideal world, neither increase nor decrease your energy usage. If you drop the whole house temperature by 5 degrees and use a weak space heater to make up those 5 degrees just in the room you are currently using, you might see slightly lower energy usage. However, the cheapest and most sustainable way to do this is with warm clothes and blankets instead of a space heater. A side benefit of the sweater approach is that you get to avoid the fire hazards often associated with space heaters. The expensive but most comfortable solution would be to install a better HVAC system.

  • Can you elaborate why you say it will only be "slightly lower energy usage"? It would seem that the amount of surface area for a whole house vs. one room would be quite a difference, and even more if the room is an interior one. Assuming a 45 degree average external temperature, lowering house temperature from 70 to 65 should decrease heat loss by 20%. – half-integer fan Nov 19 '13 at 15:14
  • Heating only one room could make a huge difference. Also, consider that if the heating is only needed for a relatively short period then a radiative heater pointing at a person will be far more effective at helping that person feel warm than a whole-house system that has to warm all of the air in the building. – Flyto Nov 19 '13 at 22:04
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I respectfully disagree with this answer.

It sounds like I myself asked the question. You described my home, my heat pump, my climate, an therefore my problem, exactly! YES, the infrared heaters make ALL the difference. Worth every penny of which I am not spending more.

Each winter is different so I'm not going to claim a savings. But, we have never exceeded our highest winter bill since purchasing the heaters and most importantly, we are WARM! Wearing sweaters, sweat pants, 2 pair of socks, and donning a blanket, while paying out the nose and still being cold is a thing of the past. Problem solved!

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    Not having to wear a sweater has nothing to do with sustainability. – sharptooth Nov 19 '13 at 12:02
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    But he didn't just stop wearing sweaters, he stopped wearing sweaters while also reducing his energy usage. If someone reduces their energy consumption through the use of targeted space heaters, isn't increasing his sustainability regardless of whether or not they wear sweaters? Energy savings increases sustainability and if more people are willing to reduce energy consumption through the use of space heaters than through wearing heavy clothes indoors, the space heaters may save more energy than the technically more sustainable sweaters. – Johnny Nov 19 '13 at 21:20
  • @Johnny: I don't actually believe into what that comment says - it sounds like a heater ad. – sharptooth Nov 20 '13 at 11:55
  • I can believe it -- while living 2 winters in a rental house with drafty windows and an inefficient and expensive to operate 1940's era gravity furnace, an infrared heater made our living room usable. Even after shrink wrapping the windows to reduce drafts, the furnace could barely maintain 60 degrees in the living room on cold winter days. – Johnny Nov 20 '13 at 16:05
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I have a heat pump and a space heater ($10 @ 1500 watt 1.5kw fan forced at Wally world).

My elect heat pump is roughly 4kw an hour, Aux is roughly 11kw an hour, together they roughly draw 15kw an hour... which usually in the coldest months run me around 1500kw- 1700kw ($150-$170).

My house is well insulated, with 3 floors. I turn my heat off, and blower is on circulate (set for 10 min cycles at 25%...or running at medium speed for 2 1/2 minutes every 10 minutes). Heater has thermostat, and is set for 68°F for 2400sq Ft home. I can easily maintain temp with just heater running for approx. 20 min or so with outside temps around 30-40°F.

Heater used approx. A third of the electricity that the heat pump runs, and a 1/8 the electricity of the Aux heat strips per kw hour.

Do the math.

So, yes, a heat pump with space heater works.

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I have a pellet stove and heat pump they say a pellet stove is more efficient than electric mine burns 3/4 of a 40lb bag in a 12 hour period a bag cost around 6 bucks plus 180 watts of power per hour to run the stove I believe let's just say total it cost 6 bucks in a 12 hour period vs. what I'm doing now on 30° plus nights(I'm trying to use my pellets for those super cold nights in the 20's or below that)I use one $15 walmart ceramic heater(1500 watts)heats the air in the room and a 1500 watt infrared heater in the next room that is connected it gets around 75° in my living room dining room kitchen and bathroom I would say it's 700sqft I keep 2 bedroom doors closed on the same level and my door that goes upstairs(if it gets to hot I crack all of them up)closed my house is approximately 1500sqft with a unfinished 1000sqft basement so here's the math using 2 space heaters 3000 watts=3 kilowatts×12 hours=36 kilowatts×10 cents a hour=$3.60 so there you have it is cheaper to use electric heat space heaters for that amount of space the pellet stove will put out more heat meaning it is more efficient at heating more sqft. for your money I guess depending on how cold it get outside also my heat pump does do a good job but the strips make it happen at 10 killawatts per hour so I just use that when I'm not home during the day and normally it is more warmer outside to add to efficiency I like using space heaters and my pellet stove just to save some wear and tear on the heat pump!

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    Welcome to Sustainable Living! I appreciate your answer, but could you please add some punctuation because it's very hard to read right now. – THelper Dec 30 '16 at 7:12

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