Heat Pump Recommendations

[theamcguy]

I live in the sand hills of NC. I have a heat pump that is 15 years old and works great. When the temps are between 30° - 50° the heat pump will put out air from the ducts between 86° - 88°. My thought is in the last 15 years heat pumps have gotten more efficient and I would like to have air coming out of the ducts at 95°+ when the outside temps are in the low thirties. Is this possible with today's heat pumps without the plates being on? Any recommendations from the HVAC guys that install heat pumps on a regular basis? TIA

 

[Jackfre]

The only way to get higher temps out is to supply higher temps to the coil. Most systems, taht I am aware of, are going to provide about a 20*temp rise, which is what you are getting out of the current system. Those higher temps would likely have to be joined with a larger evap surface area. You could also bring in your electric second stage at a higher temp. Does the output temp climb in second stage? There are things you can add like a hot water coils powered by a boiler, but that gets kinda spendy. You could also add a small wall furnace. My Rinnai’s put out about 130-135* air. Put it in the primary living area. An efficient gas fireplace would do the same,

 

[theoldwizard1]

Higher heat out does NOT mean more efficient. It does mean lower cost to operate.

In laws lived in NC, in the foothills of the Smokies. All homes with heat pumps SHOULD have a backup heat source in case of an extended power outage. They had an propane gas log fireplace. It would knock theorning chill out very quickly.

 

[P0234]

Set your thermostat to about 78 and the air coming out of the vents will be 95+!

I have a newer high efficiency 20 SEER Rheem and the vents are about a 10-15 degree delta when its on low.

 

[bonneyman]

Higher heat out does NOT mean more efficient. It does mean lower cost to operate.

In laws lived in NC, in the foothills of the Smokies. All homes with heat pumps SHOULD have a backup heat source in case of an extended power outage. They had an propane gas log fireplace. It would knock theorning chill out very quickly.

The only way I would have a heat pump is if it were a water-source unit. Alot more expensive and maintenance than the typical air-source units but they work quite well and predictably.
For me, having a water-source heat pump with wood back-up heat would be my holy grail comfort system.
Returning to reality I'm stuck with a mid-efficiency gas furnace and evap cooler/ 14 SEER A/C.

 

[pcmeiners]

"My thought is in the last 15 years heat pumps have gotten more efficient and I would like to have air coming out of the ducts at 95°+ when the outside temps are in the low thirties. Is this possible with today's heat pumps without the plates being on?"

At 7 degrees my Fujitsu heat pump was push out hot air, hotter than I could stand if the entire garage was at the same temperature. This unit has no resistance coils.

 

[u3b3rg33k]

I live in the sand hills of NC. I have a heat pump that is 15 years old and works great. When the temps are between 30° - 50° the heat pump will put out air from the ducts between 86° - 88°. My thought is in the last 15 years heat pumps have gotten more efficient and I would like to have air coming out of the ducts at 95°+ when the outside temps are in the low thirties. Is this possible with today's heat pumps without the plates being on? Any recommendations from the HVAC guys that install heat pumps on a regular basis? TIA

We've got a concord Air (lennox/LG inverter) unit at work. the air coming out of the unit feels "warm" on my skin well below 30F outside temp.

The only way to get higher temps out is to supply higher temps to the coil. Most systems, taht I am aware of, are going to provide about a 20*temp rise, which is what you are getting out of the current system. Those higher temps would likely have to be joined with a larger evap surface area. You could also bring in your electric second stage at a higher temp. Does the output temp climb in second stage? There are things you can add like a hot water coils powered by a boiler, but that gets kinda spendy. You could also add a small wall furnace. My Rinnai’s put out about 130-135* air. Put it in the primary living area. An efficient gas fireplace would do the same,

the unit I mentioned above runs off condensing/evaporator temps in stage 1 (staged by airflow), and in stage 2 it ramps to full capacity, limited by sanity (usually). so it COULD function as a 3 stage (stages 1 & 2 by airflow, 3 by sending Y2) if you wanted it to.

I've got weather compensation turned on with my Rinnai, otherwise it "over fires" and heats too fast. 130-135F air feels like you're in an oven when it's 40F outside.

 

[toyotadriver]

I have a dual fuel propane furnace/heat pump. Best of all worlds. Have the switch over temp set on 29*. Absolutely love the system. Been heating the house now for 7 years. When it's time to replace it, will replace with the same type of system.



Nothing in this post should be misunderstood, interpreted, misinterpreted, or construed to be of a political nature.

 

[theoldwizard1]

Returning to reality I'm stuck with a mid-efficiency gas furnace and evap cooler/ 14 SEER A/C.

Most of the rest of the country can't use an evap cooler !

 

[bonneyman]

Most of the rest of the country can't use an evap cooler !

Yeah, I know. Mostly the desert Southwest. But with the drought being so severe, there's talk of water rationing - and I'm sure evap coolers will be targeted.

 

[bonneyman]

"My thought is in the last 15 years heat pumps have gotten more efficient and I would like to have air coming out of the ducts at 95°+ when the outside temps are in the low thirties. Is this possible with today's heat pumps without the plates being on?"

At 7 degrees my Fujitsu heat pump was push out hot air, hotter than I could stand if the entire garage was at the same temperature. This unit has no resistance coils.

Is it one of the latest inverter compressors? I hear those are insanely efficient for their size.

 

[pcmeiners]

They are insanely efficient for now, probably not in 10 years. Mitsubishi also has models in the same efficiency ......

https://www.goodlifehvac.ca/images/Fujitsu_LZ_Series.pdf

 

[bonneyman]

Shoot! It has a base heater that comes on to keep the pan clear of ice when it gets really cold! How the heck do they get the efficiency so high if that heater comes on even a little? lol

 

[pcmeiners]

I could be wrong.....

I believe the base heater is just a stainless tube which supplies heat when the heat pump reverses to defrosts the coils, not electrical. The stainless tube seems too thin to be electrical and it is bright stainless. The defrost cycle is fairly quick.
Can anyone verify this, could not find any pictures or parts list showing the pan heater's workings.
That said the units linked above average 400% efficiency in testing.

Correction, the Fujitsu is electric but has a frost sensor at the pan, and only works when iced up, which is not often.

 

[u3b3rg33k]

Shoot! It has a base heater that comes on to keep the pan clear of ice when it gets really cold! How the heck do they get the efficiency so high if that heater comes on even a little? lol

hot gas line in the pan or electric?

 

[American Locomotive]

The base pan heater is low wattage - about 100w, but in most minisplits, they do unfortunately run just about all the time it's below freezing. Really kind of a daft design choice, and does somewhat hurt their cold weather efficiency.

 

[bonneyman]

I've always known that when HP's go into defrost it's one of the things that kills efficiency, so manufacturers do everything they can to minimize the system doing it. That was one of the big advantages of the demand defrost controls over the older time/temp versions. The unit only went into defrost when the brain determined it was absolutely necessary - and then was in defrost for the absolute minimum amount of time. (And crankcase heaters ate alot of juice, too. So many brands eliminated them as well).
Many window units had a thermostatic - expanding valve or something that was in the outside section. In summer it would expand, blocking a drain hole so accumulated condensate could be thrown on the cond coil and add to the cooling. But in winter, the bellows on the thing would contract, uncovering the hole so any defrost water could drain out. Do they not use those anymore? Simple and no electric needed for the pan.

 

[nbpt100]

I don't understand the love affair with heat pumps in the North now. I understand they are better than they ever have been. I still can not wrap my arms around how it is cheaper to operate in the north than a half decent gas or oil burner. What am I not getting?

Keeping in mind, heat pumps have an estimated 15 yr life vs. a gas or oil burner that is about 20 or 25 yrs. Plus a conventional whole house AC unit is typically 20 yrs.

 

[Yankeefarmer]

I don't understand the love affair with heat pumps in the North now. I understand they are better than they ever have been. I still can not wrap my arms around how it is cheaper to operate in the north than a half decent gas or oil burner. What am I not getting?

Keeping in mind, heat pumps have an estimated 15 yr life vs. a gas or oil burner that is about 20 or 25 yrs. Plus a conventional whole house AC unit is typically 20 yrs.

Natural gas is not available in our rural location. When I built my new shop, that left me with a choice of oil, propane, or heat pump for a heat source. We heat our house with oil, and I had heated my old shop with propane. Oil burners require regular maintenance, and both oil and propane require bulky tanks, and maintaining access to fill them when it snows. Perhaps my best alternative would have been to convert my house to propane and located a large tank somewhere on the property. But our topography is such that I can’t dig deep enough near the buildings to comfortably bury a tank and conveniently run pipe (we’re on rock), and I didn’t want to convert the house to propane since our primary living space is heated by a wood stove. So I installed an inverter heat pump for my shop, and am loving it. It shrugs off zero degree mornings, adds less than $100/month to my electric bill in the coldest months, and, best of all, no tank or need to call for a fuel delivery.
If I were building a new house, I probably wouldn’t go with a straight heat pump, because I’m not a fan of low temp air heat. But for my shop, which I heat only to about 61 deg when working there, it fits the bill perfectly.

 

[WisJim]

We bought our 2 Fujitsu hyper heat heat pumps maybe 8 years ago to use some of the surplus electrical production of our PV system. Otherwise the electrical utility paid us a fraction of what they charge for power, for our surplus at the end of the year. So the electrical energy used by our heat pumps (and to charge our electric car) was worth only a couple of cents per kW/hour if we didn't use it. Our annual total electric bill was around $500, mostly monthly meter charge, and it replaced our gas bill for the car and our heating costs for over 10 months of the year. The coldest winter months we used our wood burning furnace, burning wood from downed trees on our property.

 

[Notgrownup]

I’m about 2 hours east of you . My 21 year old heat pump runs well still . Even if the newer ones are more efficient, 3 installers told me I would never see the return on investment by just installing a new one. They all told me to use the one I have until it dies. Set it and forget it. Does it not heat your space enough? If you want more “Hot” instant heat, a heat pump is not your solution. Maybe a gas pack split unit with a heat pump to cool. I use A/C 80% of the year, not heat.

 

[P0234]

I don't understand the love affair with heat pumps in the North now. I understand they are better than they ever have been. I still can not wrap my arms around how it is cheaper to operate in the north than a half decent gas or oil burner. What am I not getting?

Keeping in mind, heat pumps have an estimated 15 yr life vs. a gas or oil burner that is about 20 or 25 yrs. Plus a conventional whole house AC unit is typically 20 yrs.

Propane prices have gone up a lot and solar has come down. I'd be on natural gas too if I could get it. But I'd run hybrid and only use it when it got well below freezing (or other inefficient times like high outdoor humidity).

 

[bonneyman]

I’m about 2 hours east of you . My 21 year old heat pump runs well still . Even if the newer ones are more efficient, 3 installers told me I would never see the return on investment by just installing a new one. They all told me to use the one I have until it dies. Set it and forget it. Does it not heat your space enough? If you want more “Hot” instant heat, a heat pump is not your solution. Maybe a gas pack split unit with a heat pump to cool. I use A/C 80% of the year, not heat.

That's the number one selling point of heat pumps locally. We don't need heat much, so folks do well if their house is newer and has good insulation. Plus, when alot of people were upgrading to A/C back in the 80's, companies sold them on heat pumps, because they could have the A/C but also get heat. They removed the old gas furnaces at that time, and people felt "safer". Plus there was a moratoriam on new gas lines around them - the gas company didn't have enough capacity with supplies to take on the huge mass of new residents moving in. So houses were pushed to be all-electric.
Also, I don't know if the general public knows this, but some manufacturers design and build their equipment differently for different areas of the country. Rheem heat pumps to be sold in the SW are built to be more cooling oriented than heat oriented. Don't know the specifics, but all Arizona heat pumps have a "JAZ" in their serial number. This was our indicator. Heat pumps for northern states or east coast areas were slightly different for those specific conditions. Can't say if Rheem still does this though.

 

[nbpt100]

That's the number one selling point of heat pumps locally. We don't need heat much, so folks do well if their house is newer and has good insulation. Plus, when alot of people were upgrading to A/C back in the 80's, companies sold them on heat pumps, because they could have the A/C but also get heat. They removed the old gas furnaces at that time, and people felt "safer". Plus there was a moratoriam on new gas lines around them - the gas company didn't have enough capacity with supplies to take on the huge mass of new residents moving in. So houses were pushed to be all-electric.
Also, I don't know if the general public knows this, but some manufacturers design and build their equipment differently for different areas of the country. Rheem heat pumps to be sold in the SW are built to be more cooling oriented than heat oriented. Don't know the specifics, but all Arizona heat pumps have a "JAZ" in their serial number. This was our indicator. Heat pumps for northern states or east coast areas were slightly different for those specific conditions. Can't say if Rheem still does this though.

I get that. Where I live you use the AC 20% of the run time and the rest is heating. You get sub zero temps most every winter and possibly for 4 or 5 days. I have natural gas service. I can not see why the heat pump will be better than a good gas furnace and an efficient whole house AC unit. If you do not have gas service it changes the calculation. I am being sold on a heat pump but I am told I have to keep my 15 year old gas furnace for back up for temps below 27F. I use a gas water hot water heater. I will not eliminate gas with the heat pump but my gas bill will be reduced dramatically. On the flip side my electric bill will be much larger. The price increases in electricity in recent years have been greater than gas. I keep hearing the grid will be overloaded and we will have brown out.

If I go with the more expensive heat pump I will still need to replace my gas furnace, in the next 4 to 6 years. Evan with the $2k tax credit on the heat pump I do not see a reasonable pay back time frame. Especially with a 15 year estimated life. This number came off of one of the manufacturers web site. I do not recall which one. Maybe York or Mitsubishi. I dont recall but i had it confirmed on a consumer website.
A dedicated AC unit is just as efficient as a heat pump. I am willing to listen and learn but I have yet to hear a reasonable story as to how it is cheaper to operate over the next 15 years.

I do get the environmental side. I am not against being greener. But there is not strong guarantee with your electricity still coming mostly from fossil fuels. And at what cost and risks. What i mean is, the risk of being shut down due to brown outs and break downs. If my ac breaks down I can get by. But not if my heat breaks down in the middle of the winter. Cost to repair. How much does it cost to repair a typical heat pump vs. a conventional gas furnace.? Some plumbers are fine with gas appliances but wont touch anything with refrigerant in it.
I know for some situations heat pumps are a decent option. I am only looking at my situation and what I am being offered.

 

[u3b3rg33k]

Is it one of the latest inverter compressors? I hear those are insanely efficient for their size.

they are when they're not using the full capacity of the system.

I've always known that when HP's go into defrost it's one of the things that kills efficiency, so manufacturers do everything they can to minimize the system doing it. That was one of the big advantages of the demand defrost controls over the older time/temp versions. The unit only went into defrost when the brain determined it was absolutely necessary - and then was in defrost for the absolute minimum amount of time. (And crankcase heaters ate alot of juice, too. So many brands eliminated them as well).
Many window units had a thermostatic - expanding valve or something that was in the outside section. In summer it would expand, blocking a drain hole so accumulated condensate could be thrown on the cond coil and add to the cooling. But in winter, the bellows on the thing would contract, uncovering the hole so any defrost water could drain out. Do they not use those anymore? Simple and no electric needed for the pan.

unnecessary timer based defrost is a real killer of useful duty cycle. when it's dry and cold out, I see very little ice buildup. 32F and foggy? so much icing!
defrost kills efficiency two ways. 1: it's time spent not heating that has to be "paid back". if you're using resistive heat during defrost, it's also time spent paying 3x for heat. often people disable the strips unless they're truly needed.

I don't understand the love affair with heat pumps in the North now. I understand they are better than they ever have been. I still can not wrap my arms around how it is cheaper to operate in the north than a half decent gas or oil burner. What am I not getting?

Keeping in mind, heat pumps have an estimated 15 yr life vs. a gas or oil burner that is about 20 or 25 yrs. Plus a conventional whole house AC unit is typically 20 yrs.

economic balance point. propane and oil are not cheap ways to heat, especially when you factor in things like tank rental, trip charge, not to mention fuel cost. I've seen propane/oil at parity for resistive heat. at that point why would you NOT want a heat pump?

 

[Notgrownup]

I was in New Brunswick Canada last year both in April and August. The Heat pump did great but it was a different one that I have in North Carolina I’m sure…

 

[u3b3rg33k]

That's the number one selling point of heat pumps locally. We don't need heat much, so folks do well if their house is newer and has good insulation. Plus, when alot of people were upgrading to A/C back in the 80's, companies sold them on heat pumps, because they could have the A/C but also get heat. They removed the old gas furnaces at that time, and people felt "safer". Plus there was a moratoriam on new gas lines around them - the gas company didn't have enough capacity with supplies to take on the huge mass of new residents moving in. So houses were pushed to be all-electric.
Also, I don't know if the general public knows this, but some manufacturers design and build their equipment differently for different areas of the country. Rheem heat pumps to be sold in the SW are built to be more cooling oriented than heat oriented. Don't know the specifics, but all Arizona heat pumps have a "JAZ" in their serial number. This was our indicator. Heat pumps for northern states or east coast areas were slightly different for those specific conditions. Can't say if Rheem still does this though.

I'm betting it's not necessary anymore with inverter units. I usually see options for coated coastal units, they seem to fare much better in salty air.

I get that. Where I live you use the AC 20% of the run time and the rest is heating. You get sub zero temps most every winter and possibly for 4 or 5 days. I have natural gas service. I can not see why the heat pump will be better than a good gas furnace and an efficient whole house AC unit. If you do not have gas service it changes the calculation. I am being sold on a heat pump but I am told I have to keep my 15 year old gas furnace for back up for temps below 27F. I use a gas water hot water heater. I will not eliminate gas with the heat pump but my gas bill will be reduced dramatically. On the flip side my electric bill will be much larger. The price increases in electricity in recent years have been greater than gas. I keep hearing the grid will be overloaded and we will have brown out.

If I go with the more expensive heat pump I will still need to replace my gas furnace, in the next 4 to 6 years. Evan with the $2k tax credit on the heat pump I do not see a reasonable pay back time frame. Especially with a 15 year estimated life. This number came off of one of the manufacturers web site. I do not recall which one. Maybe York or Mitsubishi. I dont recall but i had it confirmed on a consumer website.
A dedicated AC unit is just as efficient as a heat pump. I am willing to listen and learn but I have yet to hear a reasonable story as to how it is cheaper to operate over the next 15 years.

I do get the environmental side. I am not against being greener. But there is not strong guarantee with your electricity still coming mostly from fossil fuels. And at what cost and risks. What i mean is, the risk of being shut down due to brown outs and break downs. If my ac breaks down I can get by. But not if my heat breaks down in the middle of the winter. Cost to repair. How much does it cost to repair a typical heat pump vs. a conventional gas furnace.? Some plumbers are fine with gas appliances but wont touch anything with refrigerant in it.
I know for some situations heat pumps are a decent option. I am only looking at my situation and what I am being offered.

there are A2W heat pumps now where the outside unit is monobloc/self contained, and just has water hookups. Sanden makes one that puts out single pass 150F water/antifreeze. the coming R32 A2W units are similar.

another thing to remember is NG service usually costs $10-15/mo for the standing charge. ditching that part of the bill + gas usage can offset the potentially higher running cost for the few days a year some places see sub-zero temps.


Anyone using baseboard/radiator/infloor heat can benefit from the significantly lower temp lift and higher efficiency when you don't have to make "hot" vent air.

 

[P0234]

unnecessary timer based defrost is a real killer of useful duty cycle. when it's dry and cold out, I see very little ice buildup. 32F and foggy? so much icing!
defrost kills efficiency two ways. 1: it's time spent not heating that has to be "paid back". if you're using resistive heat during defrost, it's also time spent paying 3x for heat. often people disable the strips unless they're truly needed.

Glad to see at least someone mention this. Foggy or rain just above freezing plays havoc on a HP.

I wish I could disable my strips for defrost but have them around in case I need extra capacity, but I can't with my Econet setup as far as I can see.

 

[u3b3rg33k]

Glad to see at least someone mention this. Foggy or rain just above freezing plays havoc on a HP.

I wish I could disable my strips for defrost but have them around in case I need extra capacity, but I can't with my Econet setup as far as I can see.

my honeywell allows you to lock them out above a certain temp, but usually defrost strip use is controlled by the outdoor unit, or a communicating system.

 

[Yankeefarmer]

Glad to see at least someone mention this. Foggy or rain just above freezing plays havoc on a HP.

I wish I could disable my strips for defrost but have them around in case I need extra capacity, but I can't with my Econet setup as far as I can see.

I never installed heat strips in my system, but, if I had, they used a separate circuit breaker. Does your system not have a breaker or breakers for the strips?

 

[danski0224]

I live in the sand hills of NC. I have a heat pump that is 15 years old and works great. When the temps are between 30° - 50° the heat pump will put out air from the ducts between 86° - 88°. My thought is in the last 15 years heat pumps have gotten more efficient and I would like to have air coming out of the ducts at 95°+ when the outside temps are in the low thirties. Is this possible with today's heat pumps without the plates being on? Any recommendations from the HVAC guys that install heat pumps on a regular basis? TIA

The only way I know of to do this is with an inverter outdoor unit, and it will have to be sized larger than the indoor coil. Some outdoor units can be mated to an existing indoor coil, but I would not recommend doing that on a 15 year old system if you are paying to have the work done.

One would have to get into the heating load of the house, and then look at the heating capacity of the equipment with the outdoor/indoor equipment selections.

The "efficiency" gains come from the compressor being inverter driven. Depending on equipment feedback control, the compressor can be operating at a much lower capacity and still meet demand. This is not possible with plain old single or two stage non-inverter systems.

Installing new fancy equipment will never pay for itself if the existing is functioning and is reasonably sized. The inverter outdoor units are NOT inexpensive.

While there is some equipment that will work as part of a mismatched system, it can be better to install a complete matched system. Be aware that some of it requires a communicating thermostat and wiring between parts. New thermostat wire may be needed.

Bosch in particular has the control of the split condenser section outside, so it can work with anything and no special wiring. They are supposedly releasing communicating standard split equipment sometime this year.

 

[P0234]

I never installed heat strips in my system, but, if I had, they used a separate circuit breaker. Does your system not have a breaker or breakers for the strips?

The air handler is on those same breakers. I mean I could remove the wires for the heat strips but it would be nice to just have a menu item in the controller. It has just about any option under the sun but not don't use heat strips on defrost.

 

[Jeepster04]

Sometimes the air handler will have two breakers. One breaker does the air handler and a portion of the heat strips and the other breaker does the remaining strips. We typically turn off the second breaker unless the temps will be in the teens or lower.

 

[albertdyan]

Why do you refuse to provide us with the machine's make and model so we can research it?

Auxiliary heating strips, which may or may not be field fitted, are frequently found on the air handler of heat pumps. There will almost certainly be two disconnects in either case.


I'm not familiar with the machine you have, so I can't understand what you're looking at.

 

[bonneyman]

Glad to see at least someone mention this. Foggy or rain just above freezing plays havoc on a HP.

I wish I could disable my strips for defrost but have them around in case I need extra capacity, but I can't with my Econet setup as far as I can see.

Go old school - set up an isolation relay going to the strips. You should have a spare t-stat wire. Hook this relay between the stat aux heat wire and the strip controller, and run it form this spare wire. When off, no activation of the strips is possible if you have this secondary relay off. Even if the stat calls for it. But if you need them, flip a switch and the strips are available.

 

[u3b3rg33k]

Go old school - set up an isolation relay going to the strips. You should have a spare t-stat wire. Hook this relay between the stat aux heat wire and the strip controller, and run it form this spare wire. When off, no activation of the strips is possible if you have this secondary relay off. Even if the stat calls for it. But if you need them, flip a switch and the strips are available.

I don't even think you need to go that fancy. a SPST switch on the 24V side would be all you need, just interrupt the circuit.

 

[P0234]

I don't even think you need to go that fancy. a SPST switch on the 24V side would be all you need, just interrupt the circuit.

Not a bad idea, I could do it with a smart switch/zwave to only do it under certain conditions. I do wonder if the Econet will throw an error when it doesn't see the heat rise it wants though.

 

[JunkBonds]

Higher heat out does NOT mean more efficient. It does mean lower cost to operate.

In laws lived in NC, in the foothills of the Smokies. All homes with heat pumps SHOULD have a backup heat source in case of an extended power outage. They had an propane gas log fireplace. It would knock theorning chill out very quickly.

No, backup heat is so you do not have to rely on a HP when the weather gets too cold. For example, my HP provided heat at -18c but it took an hour to go from 16c to 20c. At -5c that 16c to 20c can happen in 5 minutes. When power is out that means my furnace doesn't work but my gas stove still does work.

HP's work efficiently and mostly constantly. They are most efficient at light loads. They are not like a gas furnace that blasts heat and then shuts off.

 

[pcmeiners]

"No, backup heat is so you do not have to rely on a HP when the weather gets too cold. For example, my HP provided heat at -18c but it took an hour to go from 16c to 20c."

That is a blanket statement, it depends if you pay for an HP which will put out 100% of the rated output at -30. Mine will do that but if my electric goes out I need a backup for heat.

 

[JunkBonds]

"No, backup heat is so you do not have to rely on a HP when the weather gets too cold. For example, my HP provided heat at -18c but it took an hour to go from 16c to 20c."

That is a blanket statement, it depends if you pay for an HP which will put out 100% of the rated output at -30. Mine will do that but if my electric goes out I need a backup for heat.

Of course and your HP won't work at -45c = -49F which Alberta saw 2 weeks of in January. That is why you need a backup source of heat.