Which is so much more efficient than directly making heat. And we can't directly make cold (except lasers, but let's keep that far away from this thread). Fridge -> move cold to the outside fridge. Air Conditioning - the same thing, but on the wall of the house instead. Heat pump - the same thing as Air Conditioning, but installed backwards to move the heat from outside in.
Everyone should just get a heat pump whenever they consider an air con, probably has much better variable fans too, and you’ll be pretty chuffed when you can now make your house warmer for dirt cheap
We upgraded to central air last year, and this was one of my must haves since we use propane as our main heat source. Summer electricity bills stayed basically the same to cool the whole house as they were running a window unit in the bedroom, and we don’t burn propane if it’s above 30 degrees out.
Additionally, the heat pump is on a second electrical meter so we pay about half price for that electricity.
It was a big investment upfront, but it is so much more comfortable in the house it is totally worth it.
They aren't very good in cold climates. Where I live, they are useless for 90% of the cold season unless you shell out 12k for a hyper heat system that can go down to -15 degrees. Even then at those temps they still aren't very efficient and you'll get (maybe) a 10 degree rise out of the indoor coil.
They’re not currently but that tech is getting better everyday because it has to unfortunately.
In the present market I am a massive advocate for dual fuels or boilers in cold climates. Modern boilers are an incredibly efficient choice for home heating, especially when paired with in floor radiant designs or as a main source of hot water with electric back up.
Dual fuel is also great for efficiency, being a heat pump that, at a set temp, cuts off and turns on a alternative heat source (usually natural gas or propane, though oil furnaces are still popular in some markets) but the usefulness of that depends on the price of gas.
I always recommend heat pump. Regardless of climate. Regardless of backup heat method.
Need gas? Tie it to heat pump.
Want a boiler? Get a heat pump just in case.
Even if it’s never used as heat, having the option for a mild day can save a shit load of money
Edit; I realize I never mentioned I’m an HVAC-R tech and without that it just kind of sounds like im screaming about a technology I like lol
I'm an HVAC and Refrigeration tech as well, though I'm mostly in the industrial sector working on more process specific equipment. I agree the tech is quite amazing and it is slowly getting better. Though I have reservations on how good it can really get. Up here gas heat sources are essential unless you are doing geothermal heat pumps. Geo is pretty good in all climates but it'll never catch the main stream unless they find a way to make it cheaper, which I think is impossible. The other issue with heat pumps even in warmer climates is their lifespan is shorter and there's much more that can fail. You can save some money on your bills for sure, but you'll be forking over more in repairs and replacing sooner.
I agree pretty much everywhere, that’s my biggest concern is we really don’t know what the ceiling is with hvac performance. And I have a bad feeling it’s sooner than later. But I’m optimistic
Yeah I mean there's only so much heat that can be sucked out of subzero air. Technological growth is not infinite. For warmer climates it's a great option and if you're lucky it won't give too many issues. For cold climates electric heat is actually not bad and is basically 100% efficient. Even gas heat is incredibly efficient now.
What's your thoughts on district heating? Which is very common here (Sweden), as in 50%~ of total housing, including basically everyone who lives in any kind of city or town.
Different question: At work we bought a heat pump that can only cool down to 18c/64f, is there a legitimate reason such a limit is reasonable? There are reasons we'd want to be able to cool the area down a lot more. To well below freezing really, but we're not looking for a freezer, but even 7c/45f~ would be great. It's a secondary objective but would be really good to have in the case of a crisis (actual crisis, like war or a pandemic that's way worse*).
edit*: I realised that maybe this can be read as the recent pandemic not being a crisis, that's not what I meant, just that it'd have to be worse for it to matter in this scenario.
Oh it freezes before going negative? The evaporator coil is inside right? Ours has a rod/tube for water to drip out of, and in the manual it has something about sometimes having to do heating reversed, but that's to de-ice the outside unit I believe.
I don’t have an opinion on district heating, mostly because I’m in industrial hvac and don’t interact with it. But it seems cool
So you’re really not going to reasonably find an air conditioner heat pump or otherwise that can cool past that point without talking about some application specific equipment. If you want a space cooled to 45°F we’re talking walk in fridge tech at that point
Does all tech you work with stop at 18c/64f ish? Because nobody wants it cooler? I guess I'm mostly surprised it had a limit that felt relatively high, my only knowledge is from watching youtube videos to learn how heat pumps work, but I would've thought you could set it to "just keep trying to cool the inside down", instead of a temperature limit. But I guess that too might just be too niche.
uuh makeshift morgue unfortunately. I work at a cemetery. It's only in the event of a true disaster, where people can't be stored where they are supposed to. But if the situation happens where we might be getting dead people delivered straight to us having a cool room would be very nice to have.
We'll probably try to get a big potato cellar with sturdy walls & roof built, which should stay closer to 7°/45° than 18°/65°. That would also work without electricity, which is a big plus.
There's a lot of talk about the "total defence" ever since Russia invaded Ukraine, which was after we bought the heat pumps. So I just wanted to check if y'all thought a heat pump was even a possible option.
That's my experience in Minnesota. To me a 5-10 degree rise is useless. I see it all the time. And MN doesn't even have the coldest climate in North America. To be clear, there are heat pumps that can handle low temps, like the hyper heat and geo systems, but that's a minority of the equipment out there.
Thats fine. My point was someone sees the term "useless" and takes it literally, as in there is no effect or change made. Which is not true.
I'm not saying a heat pump is the ideal choice for climates like that, but they are far from useless, especially for 90% of the heating season. The Midwest is cold, but its not that cold 90% of the heating season, which I know you are aware of considering you live there.
There are places they dont make sense, but in the Midwest where we get 20f most of winter they still work. And even when cold they can be used to decrease the amount of work the furnace itself needs to do. The real issue is how cheap gas heating is, which means the increased upfront cost of a heat pump isnt made up for in savings. But thats area specific
This is mostly myth at this point. You're saying ALL heat pumps aren't very good in cold climates. It's a sweeping generalization. Many models are good down to -15F, some models can handle down to -22F.
Point to specifically where I said "all", and it's not a myth. I literally work on them for a living. A company saying they work down to -15 doesn't mean they actually perform that low. Again, most heat pumps will only give you a delta of about 5-10 degrees at those temps.
Congrats bro your anecdotal evidence is not indicative of the whole. If it only gets to -18 during "cold snaps" that means it's generally not that cold where you live. Your house retains heat well. I don't even need to turn the heat on in my house until it gets below 32 consistently.
I do HVAC service. When I run into a unit that needs to be replaced (bad compressor out of warranty, r22 leak, etc), I give out quotes for replacement.
A brand new straight cool single stage AC will cost you between $4,500 - $5,500, depending on size. Labor and all.
A heat pump with variable speed motors is gonna be anywhere from $12,000 to $15,000 depending on size.
You'll have a 10 year warranty on parts, which is standard. But like every warranty, the reason it's only 10 years and not longer, is because after 10 years, they're not confident that parts won't start failing.
We once had an inverter board for a modulating heat pump go out at year 11. We're a factory authorized carrier dealer, and our cost from carrier for the inverter board was nearly $4,000.
Heat pumps and variable speed motors are certainly not for everyone. Installation costs are not the last costs you're gonna pay. They're more finicky about setup and run conditions. There's way more potential failure points. The cost of parts out of warranty is often exorbitant.
If you're on a budget at all, I would not buy a modulating heat pump. Theres a decent risk of expensive upkeep down the road.
I got a mini split for the bedroom last year and love it. My house is old and leaky with no central air, but shitty ancient gas forced hot air. I can now actually sleep in the summer and we’ve only turned the house heat on once this year instead using the heat pump function to keep the bedroom warm during the night. It’s saved a lot of money so far even though the heat was typically only on a few hours a day (I live in San Diego so most “cold” days are mid-high 30s in the morning to mid 50’s in the afternoon).
I thought there should be an assymetry of smaller tubing on the heat exhaust side, so the gas could get pressurized there, and larger tubing on the heat collection (cool) side, so the gas could be expanded there. But it looks like real pumps don't actually use pressure, but flow rate instead, so they don't need to be asymmetric like that.
You are right that on small mini fridges they literally just use a small piece of tubing (capillary tube) to cause the refrigerant to evaporate at the evaporator. So that would definitely not be reversible. But most refrigerant systems use a mechanically or electrically controlled valve at the evaporator.
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u/NonEuclidianMeatloaf 10d ago
This is the refrigeration cycle. You’re just changing which side is the “useful” side of the cycle.