We live in the peacable Kingdom North of the 49th parallel, ( actually we live on the shores of Georgian Bay in Ontario, about 44 deg North Lat,) My question is. at what point do I shut off my heat pump, ( air to air,) and turn on the electric resistance heating. I am aware that as the temp drops, the returns from the heat pump are less. At what point do I shut the heat pump off, and rely on the electric back up.
We seem to be paying .1009 cent/KWH (CDN) for electricity.
cheers,
Erwin
With the right approach, you can restore old hardware—whether through soaking, scrubbing, or polishing—giving it a fresh look while preserving its original charm.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
Good grief, man - I'm surprised someone sells heat pumps that far north. We live in Nawth Jawja, USA, and our heat pump automatically switches over to LPG as soon as the temp drops below freezing. Since it usually gets above freezing most days during the winter after the Sun comes up, we only run on LPG about 1/3 of the time from Jan to early Mar.
The advertized temp for switch over is 35 deg, F, but I've checked it out, and usually it makes it at 32.
Don
Don,
I'll just scrape the frost off of the thermometer to check what the temp is up here in the land of Universal heath Care. It's hovering at 7 Deg. (that's celsius) No snow yet.
Er
Lessee, now - 7 deg C is ABOUT 45 deg F. Hey, that's positive balmy. The bananas should still be in bloom! Believe it or not, we are already getting that low at night a couple times. Wait'll Jan.
DonThe GlassMasterworks - If it scratches, I etch it!
Check with the manufacturer.
My understanding is that you leave it in heat pump mode all year, and let it decide when it needs the back up heat - basically, it is when it can't keep up with the loads with the heat pump alone, although there are soem fancier systems out there.
And, for lurkers:
With a heat pump - leave the thermo set in one spot - if you regularly move it up and down, you'll cause the backup hat to come on each time you move it up, which is usually an expensive form of heat,
And, with a heat pump the air coming out of the registers will feel cool to the touch, but is still warming the house.
The key to forgiving others is to quit focusing on what they did to you, and start focusing on what God did for you. Max Lucado
Sojourners: Christians for Justice and Peace
Yeah, with an all-electric unit the mfgr should be able to tell you the cutover point, based on the efficiency of the pump (and assuming this is air sourced). The cost of electricity would be irrelevant. (With a dual fuel unit you need to know the relative cost of the two fuels.)
On most units the emerg heat only comes on when the indoor temp drops too far below the preset temp, which isn't really measuring efficiency. However, some newer units may have a "brain" with an outside temp sensor that figures it automatically.
As was answered by other posters, the heat pump should automatically shutdown and resistance heating take over somewhere around 32F. Keep an eye on it however. I came home one evening and found the pumps running with temps at 5 F. There should be an OTD in the unit outside, it is an Outdoors Temp. Detector which might be the culprit, altough your setup may be different than mine.
As a side note, I can't believe you have a HP that far north with resistance heating. A more suitable backup would be gas/oil. Your electric rates would plummet, but with the price of fossil fuels lately ...
You did not say what your propane cost is there.
Anway, take a look at the graph and text of the attachment, you may be able to keep running economically down to minus 10C depending on the insulation of your house.
Edit_ reread your orig post, somehow I'd gotten the impression you had propane backup, musta' got it mixed with the 'jawguh' post. .
Anyway, with all elec, the answer is simple, don't switch over until you can't keep the house warm. A lot of HP will let the HP keep running an add the elec resistance heat to it, not turn off the HP.
In WA, the lowest it gets here is about -5C in a typical winter, I have never needed run my aux elec heat on a 4T unit heating 5300 sq feet. In fact, installed a seperate manual switch to lockout the aux heat during the defrost cycle, which is a big $$$ loser if you let the aux heat come on during defrost.
Edited 10/24/2004 8:57 am ET by JUNKHOUND