Heat pump question

[weaselmeatgravy]

My Buderus oil-fired boiler is 46 years old and still going strong. I've never lived in a climate where heat pumps are viable, but we are hoping to move to Tennessee, and they are everywhere there. I have concerns because my sister in PA has a heat pump and she is always cold in the winter, wrapped up in sweaters and blankets and only has electric space heaters as backup. Most of the houses we look at in TN that use heat pumps also have some sort of more serious backup heat, like a wood stove or gas fireplaces. We've had a mild winter in Vermont this year, I don't think it has been below zero at all or maybe only for a few hours one night when I saw it was +3 the next morning. But still, my latest oil delivery on Jan 31 was $485 because heating oil (diesel not taxed for road use) prices are high ($3.89/gal). If it had been -15 for a few weeks in there, I reckon I'd be looking at $800 (although the oil company uses "degree days" to know when to deliver, so the colder the weather, the more frequent the deliveries and in frigid weather we might get them 2 weeks apart - but this last one was 5 weeks). But seeing $600 electric bills for heat pump usage is frightening. Our Jan electric bill was $169 and we have an electric water heater, dryer, and kitchen range. It seems to me that heat pumps are efficient when the outdoor temp is above about 40 and for colder snaps, you need to augment with backup heat - true? And not even run the heat pump if it is below freezing? We're having a hard enough time finding a house that checks enough of our boxes without also excluding the 90% of TN houses with heat pumps. Am I worried about nothing? Are folks with heat pumps generally happy with their performance, reliability, and cost to run?

 

[bowserb]

I'm no expert. Southeast Texas (Houston). My son in law owns an AC business inherited from his father, but he's only on the periphery of the business (so he talks a good game, but ...)

1990 new house with Lennox heat pumps 1 up, 1 downstairs. Gas furnace for backup. At that time the deal was 40 degrees for switchover to gas furnace. 10 years, two dead Lennoxes. A/C guy suggested replacing them with Trane "high efficiency" condenser units (not heat pump), as our furnaces were regular gas furnaces and gas heat is cheaper than a heat pump. Five years later, one of the furnaces dead, the other on life support (furnace is also the system air handler, so important all year. New Amana variable speed furnaces. Few years later, son in law comes into the picture when the Tranes failing. He suggests two speed American Standard condensers with our variable speed Amana furnace fans. That worked well. Oh, he also told me that Trane and American Standard were made in the same factory in east Texas.

2017 moved to new house with two Carrier condenser units and gas furnace. Learned in 2023 that the Carrier compressors have lifetime warranty--but only if the unit was registered with carrier when installed. (Builder failed to inform us of that detail, so we had only five year warranty.) Upstairs compressor unit apparently failed, according to son in law company's tech. Son in law says replace with a Gree heat pump for the tax credit and Gree is the biggest HVAC manufacturer in China and the world (note he didn't say the best, just the biggest.) I said OK. The Gree had a higher efficiency rating in A/C mode and was selectable as 4 or 5 tons, so I suggested we move the existing downstairs Carrier to service the upstairs and put the Gree downstairs. OK. He also suggested replacing the downstairs gas furnace with electric heat for additional tax credit. Luckily, the attic has no 230 volt service, so we kept the gas furnace.

Exciting conclusion coming. Gree set up for downstairs. Downstairs Carrier moved over and connected to the upstairs (it is a 3.5 ton, while the "failed" upstairs unit is a 2.5 ton.). Start 'em up. Downstairs fine. Upstairs not working--just like it was not working with the "failed" upstairs condenser. Technician: "Oh, let me check the expansion valve" (which he declined to check when he concluded that the compressor was bad). And what do you know? Bad expansion valve, and the old condenser compressor was most likely OK. So, I spent $6,000 ($4,000 after the tax credit if we actually get it) because a tech was too lazy to check all possible problems before concluding that we had a failed compressor.

What did I learn? Don't hire your son in law--even his company--to do pretty much anything.

 

[woodperson]

New heat pump should be more efficient than a 30 year old unit.

 

[ole442]

This house had an all electric HVAC system with a heat when we moved in 40 years ago. It was a 1975 model, sounded like a B17 outside and blew cool air but was the correct temp at the registers. It's a cool heat and not the hot gas heat like I was used to. Since I was poor with an almost new house (and payment) I milked that one for as long as I could. I had a newer system installed and it was all electric with a heat pump. It was quieter but still blew cool heat. We installed a new one maybe years ago with a higher efficiency unit (maybe 19 sear) and it's a tad warmer but still the heat feels cool. All of them have a defrost cycle to clear the outside unit of the frost that builds up on the heat pump. It cycles every so often and blasts the frost off when the cycle is briefly reversed.

I've had a fireplace wood stove insert for years and back in the day I'd burn 5-6 cord of wood every winter. I hadn't used it in maybe the last 15 due to working an excessive amount of hours each week. My wife has always wondered what shape our chimney was and didn't want me to burn the stove. I always pulled the large LOPI insert every year and ran brushes/rods down from the top and cleaned it out but I didn't want her to worry. I had a chimney liner installed and due to space, they couldn't direct connect the liner to the old (but wonderful) LOPI stove so we bought a new highly efficient woodstove (IHP Montlake 300 ) and it's direct connect. The law now says they all have to be direct connect. It work and does OK but the LOPI was better. I kept it in the barn to sell off sometime. The new one will heat the house and puts out very little smoke from the chimney. I guess because it's like 90 % efficient.

At any rate, I burn fires in the stove in the evening and it warms and keeps the chill off so it's nicer than with just the heat pump and I can heat my home. My wife is happy because she never wants a gas furnace due to worrying about explosions and carbon monoxide. Happy wife = happy life! It cost a small fortune. If it were just me, I'd have cleaned the old chimney and used the LOPI! I'm used to the new one but that old LOPI was a heat machine and took big pieces of firewood and you could cook breakfast on it. Can't say that for the new one!

 

[larry8]

Back in 1995 I had to replace my old gravity furnace that was put in in1953. (in Ohio that is). I chose a 2 stage Trane furnace and a seer 12 AC. My kids still live in that house and the furnace and AC are still going strong with no repairs. Only filter replacements. So for 28 years that Trane hasn't stopped. And that's why I have installed the exact same furnace and AC unit here in SC.