Heat Pumps – The Well-Tempered Future of A/Cs • Hacker News Board

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#201

Post by amluto » Wed, Jul 05, 2023, 10:55 PM UTC

__MatrixMan__ wrote: post #15

I live in a colder climate where heat pumps are not popular. After talking with a number of HVAC people about this I was surprised to learn that despite being very similar to an AC system in principle, in practice converting an AC system into a heat pump system doesn't make economic sense--you end up just ripping one out and installing the other. I don't fully understand why this is the case, but I hope that there's…

Converting an A/C to a heat pump is a bit like upgrading an old Lenovo laptop to a modern CPU. It’s surely doable, and the parts are unlikely to be terribly expensive, but as a practical matter it’s pretty specialized and no one does it.

What you do is wait for the A/C to hit end of life (or end of efficient life if new systems are enough more efficient) and replace it outright.

(I once got a quote, in an expensive market, to add an A/C to an existing furnace and, separately, to remove the furnace and add a three-head multi-split heat pump. The two quotes were almost the same price. The equipment is not especially expensive.)

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#202

Post by pkaye » Wed, Jul 05, 2023, 10:55 PM UTC

Maxion wrote: post #185

verve_rat wrote: post #172

Earlier quoted context omitted.

Yeah, as a Kiwi, watching all the debate happening here is just super weird. Meanwhile, I'm annoyed that heat pumps that dump the waste heat into the hot water cylinder aren't standard.

It's just the Yanks that have subsidised natural gas in many states, and a messed up energy infrastructure that gives electricity prices in the same range as what we have in Europe while being at war.

I was trying to find heat pump adoption rates for Europe and US.

Seems like its still pretty low in Europe outside some northern countries. Germany is less than 2000/100000 people.

https://www.theecoexperts.co.uk/heat-pumps/top-countries

Meanwhile this link says US has a 15% adoption rate across all income groups. That seems higher than I expected.

https://energypost.eu/u-s-heat-pump-adoption-is-evenly-sprea...

Is there a better source on heat pump adoption rate in Europe and US?

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#203

Post by BaculumMeumEst » Wed, Jul 05, 2023, 10:57 PM UTC

nsxwolf wrote: post #193

When I needed a new air conditioner a couple years ago I was quoted $17,000 for a heat pump. I can only guess at that point whatever energy cost savings it would bring would never be realized within the service life of the system. I went with a $6000 standard replacement AC unit.

wow that’s insane. i replaced an oil furnace with a new oil furnace + heat pump hybrid system for 7k in a high COL area.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#204

Post by shusson » Wed, Jul 05, 2023, 10:59 PM UTC

nottorp wrote: post #3

Isnt any a/c a heat pump though?

Yes modern day a/c is usually a heatpump. I’ve noticed a lot of people misunderstanding heat pumps, and thinking it’s some sort of replacement for A/C. Or that heat pumps are some new tech.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#205

Post by amluto » Wed, Jul 05, 2023, 10:59 PM UTC

rayiner wrote: post #129

jillesvangurp wrote: post #97

Earlier quoted context omitted.

This persistent myth just needs to go away. People use heat pumps all over Scandinavia, including in the arctic circle. They are extremely popular there. They were early adopters of this technology there decades ago. There are two popular varieties: - Ground source heat pumps. Those work pretty much anywhere; just dig below the perma frost and you are good to go on the northern tip of Canada, Alaska, Norway, or where…

The myth exists because the US is probably 10-20 years behind Europe and China in terms of HVAC and insulation technology. I recently had some reasonably high efficiency heat pumps installed at my house, and I’ve been very unhappy with the low temperature performance. It doesn’t even get very cold here—rarely below 5F (-15C) and a record low of -8F (-22C). The heat pumps I got (recommended by the well-regarded local…

In my local market, if you ask an installer for a heat pump, you get something from Japan or Korea. I’ve never encountered an American unit.

(I’m referring to normal air-to-refrigerant-to-air heat pumps. I know of a really weird system that is thoroughly American and an utter pain in the arse to replace because it’s specialized and undocumented. It’s quite loud, too, because it’s single-speed, and that single speed is waaaaay too high.)

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#206

Post by chongli » Wed, Jul 05, 2023, 11:03 PM UTC

SECProto wrote: post #198

nsxwolf wrote: post #193

When I needed a new air conditioner a couple years ago I was quoted $17,000 for a heat pump. I can only guess at that point whatever energy cost savings it would bring would never be realized within the service life of the system. I went with a $6000 standard replacement AC unit.

What kind of a system were you installing? We had a heat pump installed three years ago for less than $5k Canadian. Can't remember if we got a rebate on top of that or not.

We got a system for around $10,000 Canadian. But then there was a $5000 rebate.

These things are quite expensive. I think the HVAC installers are making a large commission though. The actual equipment costs much less than that.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#207

Post by mindslight » Wed, Jul 05, 2023, 11:05 PM UTC

alistairSH wrote: post #136

mindslight wrote: post #28

Earlier quoted context omitted.

I think the media has once again assigned a term their specific definition and created a meme out of it. I guess it makes sense if you have no preconceived notions of what a "heat pump" is. But yes, to anybody that knows an air conditioner is a type of heat pump, these articles read akin to "Personal cars create too many emissions. Companies have come up with an innovative way to reduce this problem: vehicles ". (wit…

It’s not the media doing this; “heat pump” has been industry lingo (in the US at least) for an A/C with a reversing value since at least the early 1980s. My parent’s house had a heat pump then and does so today (albeit much improved over the decades).

I'm aware of HVAC lingo, but that's not the entirety of it. The media is explaining them as if they're some completely different advancement, rather than focusing on the commonalities. Look at this nonsense:

> Heat pumps are also compatible with natural refrigerants with lower climate impacts. They can consume less electricity than conventional central air conditioners

Like no, any efficiency gains for cooling have nothing to do with a unit being a "heat pump". And same thing with refrigerants - adding a heating mode can only constraint the choice of refrigerants. So they're touting benefits that have nothing to do with "heat pump" and everything to do with newer technology - but instead of describing this accurately, it's just being ignorantly lumped under this "heat pump" banner.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#208

Post by tptacek » Wed, Jul 05, 2023, 11:06 PM UTC

brabel wrote: post #54

afavour wrote: post #24

Earlier quoted context omitted.

I've only ever visited Phoenix but when I did it was mid July and being outside genuinely did not feel hospitable to human life. That statement doesn't surprise me at all. Unless you're employed in, I dunno, the solar power industry I really feel like you shouldn't be living there. It should be like living on an oil rig.

Do you think people shouldn't be living in Chicago (or most of Canada and the US midwest for that matter) because without heating it's just completely inhospitable to human life during the winter? Or pretty much all Australian cities in summer?

People have lived in the midwest since long, long before modern heating.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#209

Post by amluto » Wed, Jul 05, 2023, 11:09 PM UTC

elil17 wrote: post #41

__MatrixMan__ wrote: post #15

I live in a colder climate where heat pumps are not popular. After talking with a number of HVAC people about this I was surprised to learn that despite being very similar to an AC system in principle, in practice converting an AC system into a heat pump system doesn't make economic sense--you end up just ripping one out and installing the other. I don't fully understand why this is the case, but I hope that there's…

There's no reason you couldn't just switch a couple valves out in your AC and perhaps change the refrigerant to make it into a serviceable heat pump. However, you'd need to retrofit controls/electronics, which I don't think most HVAC technicians would know how to do. It's also not advisable to attempt to DIY something like this because it is very easy to accidentally vent the refrigerant, which is a very potent green…

By the time you do that, you might as well also put in a variable speed compressor and a variable speed fan, at which point there’s not much left.

(Seriously, where I live, you will likely pay $1k or slightly more to drain and refill the refrigerant. The hardware for an entire modern heat pump, indoor and outdoor components, is maybe $3-4k. Is it really worth it to drain an old existing unit, cut the pipes, add a reversing valve, retrofit in the controls, pressure test everything, deal with the fact that the outdoor unit (formerly the condenser coil) will start producing copious amounts of condensate that the manufacturer and installer did not anticipate, and refill the system?)

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#210

Post by fireflash38 » Wed, Jul 05, 2023, 11:13 PM UTC

mason55 wrote: post #150

web3-is-a-scam wrote: post #130

My 20 year old air conditioner recently died and I was looking into replacements. In my climate the temperature ranges from 40C in the summer, and -40C in the winter. After doing some research, it seemed pretty clear that having a furnace+AC was the way to go for my climate. Hardly a magic bullet technology.

Is that the typical range in a normal year? Or is that the all-time extreme record? One thing people tend to do when they look at heat pumps is look at the typical extreme low for the year and size the heat pump based on that. But even if you touch -20 a few times a year, your heat pump doesn't need to be sized to heat in a constant -20. If you hit -20 once or twice per year then it's usually only for a few hours and…

Your best bet is also to spend a lot more on insulation. Combined insulation and efficient heating/cooling will keep your house comfortable. Overspending on one will not be as good.

You can also do heat pump for 90% of the time and emergency heat as oil/gas/wood stove.