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

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

#231

Post by nerdbert »

colechristensen wrote: post #83
silisili wrote: post #10

Earlier quoted context omitted.

Sure, but it can happen anywhere. I was just reading yesterday about a person who died in Portland of heat during the dome. Same with cold weather, if the gas/electric goes out during the winter. There's really only a few places one can live with moderate enough weather to avoid those scenarios.

Eh, it is much much easier to keep warm when it's -40 outdoors than it is to keep cool when its 120+ outside. Unless you have a terribly insulated shelter, blankets, coats, and friends will keep you warm enough to the extent that unless you are not really capable of taking basic care of yourself, you're not dying of the cold when your heat goes out. You can always do more insulation, and you only need so much for you…

Part of this is because we build houses that are terribly suited for warm climates.

I used to work in the Middle East, and their traditional structures with central pool and windcatcher/chimney design remained quite livable even when it was over 45°C outside, with zero active cooling.

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

#233

Post by anonporridge »

ashayh wrote: post #232

The article mentions the most important point towards the end: “The better you insulate, the less heat you need in the first place,” No heat pump will help if your house is leaky or under insulated.

Insulation also matters for keeping your house cool and improving AC efficiency.

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

#234

Post by northwest65 »

ashayh wrote: post #232

The article mentions the most important point towards the end: “The better you insulate, the less heat you need in the first place,” No heat pump will help if your house is leaky or under insulated.

Sure they can, you can absolutely use heat pumps to brute force it, been there done that.

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

#235

Post by tharkun__ »

newZWhoDis wrote: post #224
SkyPuncher wrote: post #218

Earlier quoted context omitted.

That must have included furnace replacement components for cold weather (e.g electric heat strips). Otherwise, heat pumps are essentially the same as modern A/C units.

Almost certainly. Proper/modern heat pumps do not need heat strips until -20F or so

Agreed. Ours is at least 5 years old if not more now and was way cheaper. That said there is a difference between mini-split and something you hook up to internal ducting where your furnace used to be and prices have increased in the meantime.

That said there was basically no difference in putting in an A/C only unit vs a combination. Technology wise it's the same so to speak just running in reverse in winter vs summer. We use the heat pump down to -15C-ish then I usually shut it down and just use the baseboard or if awake the stove (looks much nicer ;))

It was a no brainer to get the combination unit really. I don't get why it isn't the default nowadays and A/C and heating are thought of as separate concerns. We just don't have ducting, else we could A/C the whole house vs. just one floor.

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

#236

Post by nickvanw »

cwkoss wrote: post #164
zamalek wrote: post #155

Earlier quoted context omitted.

Are you sure you aren't getting quotes for a ground-sourced (AKA geo) heat pump? We just installed a 4.5 ton (overkill for your sqft) 20 seer unit for $18000.

I got a very similar quote ($27k for ~2000sqft home) in seattle a few months ago. Salesperson said there is excess demand for both labor and machinery for heat pump installations in the past few months. I wondered at the time to what extent this is a regional phenomenon (seattlites are nerds who like energy efficiency) vs. supply chain issues vs. a sales technique. Interestingly, I learned that it will be too cold fo…

I'm in Seattle, my new-ish townhouse has a heat pump and it's never been too cold for it to be functional - it's worked hard some of the really cold+snowy days the last few years, but never to the point where it wasn't heating the house up perfectly fine.

I am not sure I would pay $27k for the whole install, but once it's there I've found it to be great. Extremely inexpensive to run and with all of Seattle's power being carbon-neutral, totally guilt free to set it to 68F at night during a hot summer day.

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

#237

Post by rayiner »

amluto wrote: post #205
rayiner wrote: post #129

Earlier quoted context omitted.

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 i…

The Asian brands make products for the US market—often through subsidiaries that were originally US companies, such as Goodman and Amana. Basically stuff that complies with US codes and standards, and that US HVAC installers can fix without learning anything new. Daikin makes a ton of stuff they don’t sell in the US. Owens Corning makes high density fiberglass batts you can buy in Canada but not in the US.

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

#238

Post by 0x53 »

cwkoss wrote: post #164
zamalek wrote: post #155

Earlier quoted context omitted.

Are you sure you aren't getting quotes for a ground-sourced (AKA geo) heat pump? We just installed a 4.5 ton (overkill for your sqft) 20 seer unit for $18000.

I got a very similar quote ($27k for ~2000sqft home) in seattle a few months ago. Salesperson said there is excess demand for both labor and machinery for heat pump installations in the past few months. I wondered at the time to what extent this is a regional phenomenon (seattlites are nerds who like energy efficiency) vs. supply chain issues vs. a sales technique. Interestingly, I learned that it will be too cold fo…

Putting mine here for reference as well: 12k for complete heat pump and air handler install using existing ductwork.

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

#239

Post by alistairSH »

mindslight wrote: post #207
alistairSH wrote: post #136

Earlier quoted context omitted.

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 n…

It’s not just a heat pump thing, it’s the entire industry. The state of science and tech journalism is pretty sad right now.

That’s what happens when few people are willing to pay for quality research and writing.

All that said, it is relatively recently that Americans have had access to heat pumps this efficient and they work reasonably well in sun-freezing temps.

I grew up with heat pumps. It was pretty normal for it to kick into emergency (electric heat element) when the weather got nasty (for DC, so the mid-teens F).

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

#240

Post by thrashh »

nerdbert wrote: post #211
samtho wrote: post #49

Earlier quoted context omitted.

An A/C works almost identical to your refrigerator. Using a closed loop of refrigerant with specific thermal properties, it will remove heat from one side and emit heat from the other. If you are able to run this system backwards, you could in theory swap which side is a heat sink (the cold side) and heat source (the hot side). While a traditional A/C cannot do this, heat pumps can electronically switch which side of…

> Fun fact, a resistive heating device is a rare case of something being 100% electrically efficient in that all the energy it uses will be turned into heat My understanding is that you get considerably more heating per watt-hour with a heat pump than with resistive heating, though. I get that it's not creating that heat but moving it, but still that seems like even more efficiency from the perspective of energy cons…

Well the word “efficient” always needs context. You have to define the goal first before you can define efficiency.

OP said electrical efficient so the goal is conversion of electricity to heat and it’s 100% efficient.

Even an electric heater compared to a propane heater is more electrically and energy efficient, but it’s not as storage-efficient (because fossil fuel gases have much higher energy density per volume AND weight than lithium batteries).

A heat pump is more electric bill-efficient.

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