Propane gas furnace or heat pump? (Bristol: 2015, coop, new home)

[Lake-girl]

Hi! We are planning on building an 1800 sq ft house on Cherokee Lake. We are contemplating between a propane gas furnace or a heat pump. The neighborhood does not have natural gas available, so a gas furnace would have to be propane. We currently live in the frozen tundra (Minnesota), so we have no experience with heat pumps. We've researched heat pumps, but we still don't have a clear understanding of which would be the better option for that area. Any advice would be greatly appreciated!

[Badbird2000]

Heat pumps lose their efficiency when the outside temperature dips below about 45 degrees. They are typically fitted with an electric strip heat that activates below that temperature. I grew up in Florida, and we had a heat pump. It worked great with the exception of a very few cold days (below 40 degrees). My house up here has gas heat, and the discharge temperature in heating is about 90-95 degrees. Heat pumps discharge around 80-85 degrees. I would suggest a duel-fuel system. They utilize a heat pump for heating during milder temperatures, but have the ability to switchover to use gas heat when the outside temperature drops below a determined temperature. That would give you the best of both worlds.

[GraniteStater]

Go with a two stage heat pump system. Modern heat pumps are far more efficient at lower temperatures than the ones that were manufactured decades ago. I was away from my property in southern Indiana and the heat pump worked just fine by itself with no other alternate heat sources at -10F outside temperature with a -30F wind chill last December.
With the very mild/warm climate in eastern Tennessee, you won't have much of any "winter" at all for the most part, just make sure to improve the insulation to lower the energy costs of the structure.

[DubbleT]

Originally Posted by Badbird2000

Heat pumps lose their efficiency when the outside temperature dips below about 45 degrees. They are typically fitted with an electric strip heat that activates below that temperature. I grew up in Florida, and we had a heat pump. It worked great with the exception of a very few cold days (below 40 degrees). My house up here has gas heat, and the discharge temperature in heating is about 90-95 degrees. Heat pumps discharge around 80-85 degrees. I would suggest a duel-fuel system. They utilize a heat pump for heating during milder temperatures, but have the ability to switchover to use gas heat when the outside temperature drops below a determined temperature. That would give you the best of both worlds.

I don't believe that still holds true. My heat pump is 15 yrs old and doe just fine, only utilizing the electric strips when we get down into single digits temps. So auxilary electric is only used basically several days to a week each year, and that's here in Bristol which sees slightly colder temps than Knox. I would imagine newer heats pumps are even more efficient.
OP, maybe talk with your local utility provider for more information/suggestions?
My local provider has a program to help people purchase heat pumps.

PS If you've never been in a home that uses heat pumps it may seem odd to you as the air it pumps out does not feel as warm as you might expect from an alternate heat source.

The air could be warm but still feel cool
Heat pumps usually produce air that is 85-92°F. This is plenty warm to heat your home to your desired 72°F.

But, the air coming out of the vents can feel cold for a couple reasons:

Gas furnaces produce air that is 130-140°F range. So 85-92°F feels cold to new heat pump owners.
Your body temperature is around 98.6°F (everyone’s body temperature is slightly different, but that’s the average). Since heat pumps produce air that’s below that, it can feel cold to you.

https://www.coolray.com/help-guides/...old%20to%20you.

[GWoodle]

You may save a lot in the summer with the heat pump. Sometimes depends if your windows face south or west in the heat of the day. Having ceiling fans or regular floor fans to keep air moving helps. Also consider an air cleaner if you have allergy problems.

In the winter seldom gets down to zero.

You will have to check the cost of electricity vrs propane gas. Because of low TVA rates electric may be your best option.

Also consider if you do electric heat pump for water vrs gas. You may want gas water heater.

[Chas863]

I would go with a heat pump, but would install some small propane powered stove in the basement as a backup in case the electricity goes out for a long period. Or, you could purchase a couple of small, portable propane heaters to use in case of emergency.

I've had heat pumps for the past 42 years and wouldn't go back to gas unless I had no other choice.

[Barking Spider]

BadBird is thinking of his Grandfathers heat pump. Newer multi speed and multi stage heat pumps will go below freezing before they start using Emergency heat. In 2014 I went with a multi stage multi speed heat pump, and my utilities dropped $1100 per year (old system was gas heat circa 1993).
2015 was a very cold winter and my emergency heat on came on 4 times the entire year. Go with heat pump.

[SDbp]

Originally Posted by Barking Spider

BadBird is thinking of his Grandfathers heat pump. Newer multi speed and multi stage heat pumps will go below freezing before they start using Emergency heat. In 2014 I went with a multi stage multi speed heat pump, and my utilities dropped $1100 per year (old system was gas heat circa 1993).
2015 was a very cold winter and my emergency heat on came on 4 times the entire year. Go with heat pump.

I had a new home in Lincoln NE (for a year) that had (I think) only a heat pump installed. It did OK, but I did notice that it heated up slower from colder temps (like when I got home from work) than say my IL home that had gas heat only. OP might look into whether the local utility has any rebate programs. My local utility is trying to get people to switch over to heat pumps.

We also have a monthly newsletter the electric coop puts out that has good info this month (JUL) on heat pumps. Unfortunately, they do not have it up on the website yet, so I can't link it. OP might take a look later on at the JULY 2023 issue when it posts at:
https://www.siouxvalleyenergy.com/co...ons-newsletter

They have a nice table of comparisons to other heating options. The baseline they give is for the coop's heating rate of 6.35 cents per KWh and a 8.2 HSPF heat pump used mostly in OCT, NOV, MAR and April. I assume they leave out the dead of winter months out of the table as it's too cold here in SD for heat pump as the primary heat source. But I assume these warmer months would be like a TN winter.

For those somewhat warmer months, they say to beat the heat pump on costs:

a 96% efficient propane furnace would have to use propane at 68 cents a gal or less
a 90% efficient propane furnace would have to use propane at 64 cents a gal or less
a 96% efficient nat gas furnace would have to use gas at 74 cents a therm or less
a 90% efficient nat gas furnace would have to use gas at 70 cents a therm or less

I assume they expect you to have a backup system here on the frozen prairie as they go on to say:

"With trends of increased rates for fossil fuels, pairing your system with a heat pump also gives you another energy choice for heating. A base model air-source heat pump has a heating seasonal performance factor (HSPF) of 8.2 will typically be set to operate in the mid-20 degrees and above for heating before the back up is needed. Units with higher ratings (9s and 10s) are considered cold climate heat pumps that can operate in much colder temperatures, requiring less of a back up system."

[TheShadow]

We have the best of both worlds. We have a highly efficient new dual-fuel heat pump with propane as the auxiliary heat instead of electric strip heat. When the temps get down to freezing levels, which really does happen quite a bit at night in Tennessee winters, it switches to propane as the heat source. It really makes the house cozy without costing a fortune. It doesn't use much propane because it's usually only for a few hours a night. Last winter was a cold winter exception when we had a couple of weeks straight where the high temp for the day was below 32 every day. Our monthly electric bill has never been over $160 for a 3000 sq ft home, although I admit that helping people lower their utility costs was what I did for a living for 20 years, so it had better be low! Our annual propane bill is about $500 for the stove, dryer, water heater, and heat pump aux heat. We have a large propane tank we fill once a year so we get the best price on propane.

[Kefir King]

Can any proponents of heat pump engines tell me when they revoked the law that made ICE at 32°F?
When the outside coils freeze up, all heat transmisssioon STOPS until a defrost (expensive) cycle melts the ice.

Since to transfer heat FROM a cold body requires the cold body go very low

I know there is a lot of WISHING going on here but wishing will nopt change the Laws of Thermodynamics.