Heat pumps again

[tankd0g]

The garage I'm building is going to be pretty short on space. I'll have pex in the floor for solar but it will not be hooked up for this first winter. I can get a hanging oil furnace to save space but I am considering a split heat pump since it takes up virtually no interior space. One barrier to this may be that I'll only have a 50A 240v service to play with.

I really know nothing about these other that the local utility sells a Fujitsu unit that can be financed through them for a considerable markup. I'm in Canada and although the winters are growing much milder in recent years, we still get down to -25C, with -10C to -15C being the more common temperature. Is it even worth considering a heat pump in this climate? I really like the idea of having AC in the summer in there since I'm not planning to put any windows in, it's only a 24x24' 12' ceiling, R19/21 insulation and an insulated door. I only want to keep it above freezing over the winter to protect the lift hydraulics and of course the drywall. The few times I would actually be in there using the lift in the winter I could use a propane heater to make it comfortable. I have another 24x16' garage that is not insulated but has a big old oil hot air furnace that heats it up in no time.

I've read the discussions on here about heat pumps that I could find with the search, I didn't see much talk about power requirements though.

 

[Jackfre]

getting a "bid old" old furnace will not save you a lot of space either as you will need an interior tank for #2. If you go with an outside teank with those temps you will have to run K-1.

Be aware that the Fujitsu units (9, 12 & 15k btu models) are able to heat down to -15f.

 

[tankd0g]

getting a "bid old" old furnace will not save you a lot of space either as you will need an interior tank for #2. If you go with an outside teank with those temps you will have to run K-1.

Be aware that the Fujitsu units (9, 12 & 15k btu models) are able to heat down to -15f.

I may have over stated how cold it gets here, I have an external #2 tank and the fuel has never gelled up on me, people typically only have problems here if they have water in the line.

I know some of the heat pumps claim to heat down to -15F, but are they relying on a resistive element to do that? I haven't really found any hard numbers on what they supposedly save in heating costs and if the savings people do claim are only over straight resistive element heating, which is by far the most expensive way to heat your home here.

 

[tylernt]

As far as I know, heat pumps can operate down to about 0°F. I believe -15° would be straight resistive emergency heat.

To compare a heat pump useage costs to various other fuels like gas or oil, check this out:

www.eia.gov/neic/experts/heatcalc.xls

 

[theoldwizard1]

One barrier to this may be that I'll only have a 50A 240v service to play with.

My gut says you will be fine, as long as you don't fire up a big welder at the same time. A big (5+ hp) compressor might be an issue also.

 

[tankd0g]

As far as I know, heat pumps can operate down to about 0°F. I believe -15° would be straight resistive emergency heat.

To compare a heat pump useage costs to various other fuels like gas or oil, check this out:

www.eia.gov/neic/experts/heatcalc.xls

Thank you, this is the sort of comparison I was trying to track down. It's handy that it's a spread sheet because the cost of electricity wherever this is from is just about half what it is here!

 

[Scott r c]

If you question at what temp the heat pump is no longer effective and the emergency heat kicks on, it is above freezing. My heat pump goes to backup heat around 45'F

 

[Jackfre]

There is no back-up heat in a mini-split. They cannot add elec supplemental heat with a plastic case. The -15* heating is done by the heat pumps normal operation. I believe that Groupmaster is the Canadian Dist. For Fujitsu. I'd check with them for Canadian case studies.

 

[tankd0g]

There is no back-up heat in a mini-split. They cannot add elec supplemental heat with a plastic case. The -15* heating is done by the heat pumps normal operation. I believe that Groupmaster is the Canadian Dist. For Fujitsu. I'd check with them for Canadian case studies.

If I'm reading their information correctly, they claim the 1 ton unit puts out 12,000 btu/h at -26C and about 16,000 at -10C, does that sound about right? That's not a hell of a lot of heat but it should keep things above freezing.

 

[Jackfre]

You are correct. It is not a great deal of heat, but you are talking about the very extreme of your weather. I think if you look at the Canadian weather data for your area, and this is conjecture on my part based upon what I know of US weather, it will be in those super low ranges for very short times, probably less than 2-3% of the heating year. US weather data is called BIN numbers and they have 25 yr averages of hourly temperature data from many reporting weather stations.

If you are concerned about that and want heat only I'd suggest a Rinnai EX-38 DV heater. That wiil definitely take care of it, but you have no cooling.

 

[tankd0g]

You are correct. It is not a great deal of heat, but you are talking about the very extreme of your weather. I think if you look at the Canadian weather data for your area, and this is conjecture on my part based upon what I know of US weather, it will be in those super low ranges for very short times, probably less than 2-3% of the heating year. US weather data is called BIN numbers and they have 25 yr averages of hourly temperature data from many reporting weather stations.

If you are concerned about that and want heat only I'd suggest a Rinnai EX-38 DV heater. That wiil definitely take care of it, but you have no cooling.

If we had natural gas available here I would have everything running off of that, it must be great to be able to have small direct vent alliances for everything. We are pretty much stuck with fuel oil, wood or electricity. I have a pellet stove in the house which is working well but it's not practical for a garage.

 

[EOC_Jason]

You have to realize when the heat pump is in "heat" mode, it's just an A/C unit flowing in reverse. Your evaporator coil is what is cooling off the freon (and heating the room) while the compressor is trying to pull the heat from the air outside.

I would really double check the specs, and / or call the manufacturer. I've seen heat-pumps that have iced over and turned to popsicles outside. Without resistive heat strips you are SOL in that setup if the temp drops too far.

 

[tankd0g]

You have to realize when the heat pump is in "heat" mode, it's just an A/C unit flowing in reverse. Your evaporator coil is what is cooling off the freon (and heating the room) while the compressor is trying to pull the heat from the air outside.

I would really double check the specs, and / or call the manufacturer. I've seen heat-pumps that have iced over and turned to popsicles outside. Without resistive heat strips you are SOL in that setup if the temp drops too far.

The physics does seem to defy common sense on these things, I was really hoping there would be someone on here from Canada who had one of these units installed. The old stand by of a used oil furnace off Kijiji might be this years heat source at least until I get the solar panels up.

 

[tylernt]

Dunno about split heat pumps, but traditional air handler heat pumps will run in A/C mode (cooling the house / heating the outside coil) and turn on the emergency resistive heat strips periodically to de-ice the outside coil.

If you've got a split with no emergency heat strips, the de-ice cycle is going to ****...

 

[dellwas]

Where abouts in Nova Scotia are you? I'm on the South Shore and will be watching this with interest. Three or four of us will be doing a group buy sometime this summer.

BTW, my 24x24 garage is unheated and I can work comfortably in it down to about -25 comfortably. Went nuts with the insulation when I bought it though.

The garage I'm building is going to be pretty short on space. I'll have pex in the floor for solar but it will not be hooked up for this first winter. I can get a hanging oil furnace to save space but I am considering a split heat pump since it takes up virtually no interior space. One barrier to this may be that I'll only have a 50A 240v service to play with.

I really know nothing about these other that the local utility sells a Fujitsu unit that can be financed through them for a considerable markup. I'm in Canada and although the winters are growing much milder in recent years, we still get down to -25C, with -10C to -15C being the more common temperature. Is it even worth considering a heat pump in this climate? I really like the idea of having AC in the summer in there since I'm not planning to put any windows in, it's only a 24x24' 12' ceiling, R19/21 insulation and an insulated door. I only want to keep it above freezing over the winter to protect the lift hydraulics and of course the drywall. The few times I would actually be in there using the lift in the winter I could use a propane heater to make it comfortable. I have another 24x16' garage that is not insulated but has a big old oil hot air furnace that heats it up in no time.

I've read the discussions on here about heat pumps that I could find with the search, I didn't see much talk about power requirements though.

 

[dellwas]

That would be the Master Group:

http://www.master.ca/en/consumers/index.sn

Not only Fujitsu, quite a few others as well.

There is no back-up heat in a mini-split. They cannot add elec supplemental heat with a plastic case. The -15* heating is done by the heat pumps normal operation. I believe that Groupmaster is the Canadian Dist. For Fujitsu. I'd check with them for Canadian case studies.

 

[tankd0g]

Where abouts in Nova Scotia are you? I'm on the South Shore and will be watching this with interest. Three or four of us will be doing a group buy sometime this summer.

BTW, my 24x24 garage is unheated and I can work comfortably in it down to about -25 comfortably. Went nuts with the insulation when I bought it though.

I'm in Cape Breton, I'm mostly concerned about keeping my tools and the hydraulics in the lift from getting killed by the cold. What is it you are planning to buy?