Mosho1 wrote: ↑ Hello, the new rebate program has a $5,000 grant for new cold climate air source heat pumps. I currently have an old (27 y/o) ducted AC system that works okay but I was thinking this is a good opportunity for a replacement. However, when I looked at heat pumps in the past you still needed supplementary heat (electric or gas) in the winter. I was wondering if this is still the case, or have new heat pumps evolved to the point where they can handle -20 celcius?
The answer to all heat pump questions is 'it depends.'Mosho1 wrote: ↑ Hello, the new rebate program has a $5,000 grant for new cold climate air source heat pumps. I currently have an old (27 y/o) ducted AC system that works okay but I was thinking this is a good opportunity for a replacement. However, when I looked at heat pumps in the past you still needed supplementary heat (electric or gas) in the winter. I was wondering if this is still the case, or have new heat pumps evolved to the point where they can handle -20 celcius?
With supplemental heat cycling on and off, it should have kept up - installer/contractor error. Unless I misunderstood and you meant it kept up down to -10 without supplemental heat.MrFrugal1 wrote: ↑ My last house in Toronto had an air source heat pump with a supplemental electric furnace. It was 1945 era bungalow, typical of huge swaths of East York, with a double brick wall and 3/4" air gap as the only insulation other than the attic. The heat pump could not keep up with the demand of anything below -10C.
It was probably ten years old when I bought the place, (so early '90's build), but that doesn't mean technology has improved to the point of defeating the laws of thermodynamics. Heat pumps work best in more moderate climates, especially when thermal loss through the building envelope is less rampant.
A heatpump with gas heat for very cold weather is a really common setup.
That's no longer the case; as a example MITS Air makes a cold climate unit that's designed to be used with your existing air handler/furnace. I know of at least one or two in the field I've seen that goes down to around -17 to -20 deg. C in a modern 2500 sq ft. bungalow on the Bruce Peninsula before requiring aux. heat. Mind you it's a 3 ton unit, but with the invertor drive it still runs as you'd except as an ac in the summer.middleofnowhere wrote: ↑ A heatpump with gas heat for very cold weather is a really common setup.
Unfortunately, high-end heat pumps that can work at -20 (such as Mitsubishi's Zuba) generally require matching air handlers/furnaces. As far as I'm aware, heatpumps that can be installed alongside a standard furnace can only provide enough heat to be useful in a Toronto climate down to zero degrees. If you go this route, plan on using your heat pump for heat only in late spring and early fall.
To get the rebate, the heatpump would have to be a approved match for the heatpump, and a 10 year old goodman won't be.
Thanks for this information.von Monster wrote: ↑ That's no longer the case; as a example MITS Air makes a cold climate unit that's designed to be used with your existing air handler/furnace. I know of at least one or two in the field I've seen that goes down to around -17 to -20 deg. C in a modern 2500 sq ft. bungalow on the Bruce Peninsula before requiring aux. heat. Mind you it's a 3 ton unit, but with the invertor drive it still runs as you'd except as an ac in the summer.
The brochure lists the SEER, COP, and the HSPF5; you can do some math from there if you wanted - but I agree they should have more information on their website. They definitely used to to have a nice chart with cold weather performance on it but the website has been resigned since the last time I was on it. You can also get a bit more information on the unit by looking at the specs with the matching air handler - https://www.mitsair.com/wp-content/uplo ... re-7-1.pdfinsertname2020 wrote: ↑ Thanks for this information.
I looked it up and it is controlled with a regular thermostat, no mention in the manual of how it modulates - using algorithm or otherwise. No sequence of operation info.
The spec sheet does not show heating capacity at lower temperatures.
Seems they don't like to publish much info.
Not efficient enough to qualify for rebates.
Bosch has one that maintains capacity better than regular and can be used with a regular thermostat and they published much more info to really get an understanding of how it works.
insert :not sure if serious: meme picture I guess?GoodFellaz wrote: ↑ who actually lives in these houses with heat pumps? every house ive seen is furnace, older homes were radiator
The bosh modulates to maintain consistent head pressure in heating mode and suction in cooling mode.von Monster wrote: ↑ The brochure lists the SEER, COP, and the HSPF5; you can do some math from there if you wanted - but I agree they should have more information on their website. They definitely used to to have a nice chart with cold weather performance on it but the website has been resigned since the last time I was on it. You can also get a bit more information on the unit by looking at the specs with the matching air handler - https://www.mitsair.com/wp-content/uplo ... re-7-1.pdf
The modulation is controlled by the interface box - it's a Midea unit (same as the outdoor unit; and to my eyes it looks identical to the units they sell Carrier) - but I can't seem to Google this morning and am only coming up with the mini-split interface board. It will be a proprietary algorithm based on internal (return air) and external temps with some 'secret sauce'. I'm not aware of any company that discloses how it's algorithm works; in any case using a dumb tsat it runs the pump until it no longer is able to keep up with heating and then swaps to AUX; with a smart tstat you can set lock outs and more directly control whether to use the pump or AUX, you just can't set the heat pump invertor.
Oddly enough they've moved a pile of information into their 'training course' which is weird, but I'm guessing a lot of these are installed by people without a large amount of heat pump / dual fuel experience.
Also the rebates are only eligible if it's on the Greener Home rebate list - these Mits Air units are not, but very similar model Midea units are so an email will likely lead you to the eligible Midea unit; on the flip side both units I've seen installed were more than the rebate less than the Carrier/Trane/Lennox equivalents.
I have one. They're pretty common here on the west coast.GoodFellaz wrote: ↑ who actually lives in these houses with heat pumps?
