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Harnessing America's heat pump moment

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Re: Harnessing America's heat pump moment

#141

Post by gwbas1c »

My mini-split was installed sometime between fall 2017 or spring 2018 when my house was built. It failed when it was 6 years old, and the lineset had to be replaced because there was too much acid in the insulation and it corroded the copper.

The problem was that the lineset was in my walls, so replacing it would require ugly lineset in a highly-visible place on my house. All the quotes to fix / replace it were absurdly expensive.

Because the mini-split was for a room that I use occasionally, I just use a portable air conditioner and a space heater.

Re: Harnessing America's heat pump moment

#142

Post by orev »

mithr wrote: post #26

Electricity costs are a big factor in this, imo. Rates for my northeast town increased by ~25% in 2024 and are going up by another ~10% this year. It's a hard sell to spend a large amount of up-front money (even after rebates, which decreased this year) to convert to a system that will cost you more than you pay today, and may not work as well in cold weather (every heat pump company I talked to suggested keeping my…

Heat pumps are just air conditioners in reverse. They use the same amount of electricity whether heating or cooling. While many people have air conditioners, and grids seem to be able to handle them in the summer, an assertion that the grid can’t handle them in the winter is doubtful. Plus there are fewer people using them in the winter (just because fewer are installed). Most people in the NE heat with oil, gas, or wood, so that would reduce the electric load (compared to summer) even further.

There would be an increase only if people were supplementing the heat pump with electric heat, which to be fair is a possibility.

There’s a lot of misinformation about heat pumps, especially by HVAC people who don’t have a lot of experience with them, so they tend to recommend what they’re more familiar with.

But yes, understanding the electricity cost is essential when considering one.

Re: Harnessing America's heat pump moment

#144

Post by kragen »

gwbas1c wrote: post #140
kragen wrote: post #128

> what it’s going to take, from the human side of the equation, to make heat pumps the obvious, accessible, and default choice for millions of American homes. Well, this has already happened; living in a third-world American country, I've been heating my houses in winter with heat pumps every winter for many years (even though they iced up occasionally) and most air conditioners here are already heat pumps. Frio/calo…

Remember: The season that you need heat is the season with the least sunshine. Solar is only cheap as you claim due to net metering; without pairing it with batteries or some other form of storage, you're pushing your heating cost on others by flooding the grid with electricity when it isn't needed. Now, I will gladly point out that I have a roof of solar panels, and benefit from subsidies: It's important to understa…

No, I'm not talking about net metering, which has nothing to do with the cost per peak watt.

You're right that you do need energy storage, though. Even sensible-heat thermal energy storage is completely adequate for this purpose, and it's very cheap, on the order of US$2–3/kWh. See the sand-battery outline I wrote yesterday in https://news.ycombinator.com/item?id=45690085. Electric night storage heaters are widely available off the shelf in many countries already, though not in the US.

For some other kinds of energy storage, it's debatable whether utility-scale storage or household-scale storage is more efficient; you're trading off economies of scale against transmission and distribution losses and transaction costs. But low-grade thermal energy storage is clearly better at household or neighborhood scale; my design outline linked above comes to a price per kWh that's 3% of the price of the batteries needed for BESS, and maybe 15% of the optimistic cost estimates for sodium-ion. You have to reduce the energy to low-grade heat up front to store it so cheaply, but that makes it hard to redistribute later—to redistribute low-grade stored heat from a central energy storage facility, you need something like New York's steam district heating systems. It's far cheaper to store the thermal energy at the point of use.

This is not a new idea. It's the idea behind adobe walls, Russian stoves, rocket mass heaters, electric night storage heaters, dol beds, kachelofens, kangs, earth-bermed walls, Trombe walls, and ondols. People have been doing this for 7000 years, without an electrical grid or, for that matter, electrical power at all. It definitely doesn't rely on net metering!

Re: Harnessing America's heat pump moment

#145

Post by ssuds »

gwbas1c wrote: post #141

My mini-split was installed sometime between fall 2017 or spring 2018 when my house was built. It failed when it was 6 years old, and the lineset had to be replaced because there was too much acid in the insulation and it corroded the copper. The problem was that the lineset was in my walls, so replacing it would require ugly lineset in a highly-visible place on my house. All the quotes to fix / replace it were absur…

Quality control by the contractor is soooo important. Formicary corrosion like you described can happen if a contractor doesn't pull a proper vacuum on the system to evacuate moisture before releasing refrigerant. I saw an anecdote where Bill Spohn, who literally owns an HVAC tools company, had this happen with the contractor installing a system in his own house! (https://www.heatpumped.org/p/are-heat-pumps-a-commodity)

I suspect it's especially bad with new builds, as new builds are a race to the bottom and every subcontractor is fighting to get the lowest bid. The best way to make it cheaper is skip steps, and that hurts in the long run. Sorry you ended up in that situation, crummy experiences like this set the industry back. For what it's worth, the same corrosion could happen with a traditional AC system too (it's not just heat pumps). But the difference is, often those refrigerant lines don't get as hidden on interior walls as the ones for ductless mini-splits do.

Re: Harnessing America's heat pump moment

#146

Post by sitharus »

darth_avocado wrote: post #57
galoisscobi wrote: post #3

> we’re waiting on people Right on. I have a heat pump water heater and a heat pump heating system in my HVAC. Getting those installed felt like swimming upstream. Most contractors would try to dissuade me from them. Luckily, I found a contractor who was skilled and knowledgeable about heat pumps and rebates (back when govt thought climate change was real). Very happy with my heat pump tech.

I’m in California, I have two heat pumps installed. I can sum up the problems as follows: 1. They are EXPENSIVE. The equipment itself isn’t that expensive tbh but installation is pretty expensive. The government subsidies have made sure that the contractors jack up their own prices by as much. 2. I end up paying more in utilities because electricity is very expensive and heat pumps aren’t nearly as good at heating in…

I was shocked when I saw the price of heat pump installation in the US, even with an existing ducted system. There’s no reason a reversible heat pump system should be significantly more expensive than a cooling only one.

Re: Harnessing America's heat pump moment

#147

Post by sokoloff »

doctorhandshake wrote: post #98
VWWHFSfQ wrote: post #42

Earlier quoted context omitted.

A heat pump just makes no sense whatsoever for me in my northeast town. The electric bill alone would outpace the old propane bill, not to mention installation. And it won't even work during some of the coldest winter weeks when you _really_ need it to work. Maybe I would consider it if I was in, like, Nevada or somewhere.

The notion that heat pumps don’t work at low temperatures hasn’t been true for years. I think you may be surprised to find that just about any heat pump you look at has good efficiency down to very low temperatures.

They have good heat output down to very low temperatures, but not good efficiency.

The CoP is often around 2.0 at those very low temps, though (and of course the heat energy demanded is higher).

Re: Harnessing America's heat pump moment

#148

Post by danielsju6 »

Maybe I have scar tissue from COVID prices but $20k to install a ductless heat pump vs. a $200 to throw a window A/C in or $700 for a portable heat pump. While I get that these heat pumps are better for the environment and much more efficient it's a last mile issue. The installers charge an arm and a leg and I'm not hurting enough to self install. I'm hoping the window heat pumps that just run off mains will be available to more markets soon, I could buy one of those for every room in my house for less than the install on a single mini split.

Where it did make sense was when I was getting solar. It was only a few thousand since I already had the trades out and reducing the load was important for the ROI on the panels.

Re: Harnessing America's heat pump moment

#149

Post by ssuds »

kragen wrote: post #134
ssuds wrote: post #132

Earlier quoted context omitted.

I presume you're not in the US - the numbers you quoted here align with the costs I observed for heat pumps in India ( https://www.heatpumped.org/p/you-can-have-it-in-any-color-as... ) Skilled labor in the US is expensive! Most of the install costs come from labor, not equipment. Tens of thousands of dollars is pretty typical for a heat pump installation. (For what it's worth, the person you're quoting is referencing…

Yes, it's just a mini split. Two guys (skilled, but AFAIK not licensed) installed it in about 6 hours. I'm in Argentina, but I don't think US$1000 an hour is a common labor rate even in the US? Maybe for a famous lawyer or surgeon?

Ha. It's not straight labor. So much other overhead to consider - workman's comp insurance, back office staff, technician utilization, vehicle repair and maintenance, etc... There are lots of other costs that get baked in when you're looking at a licensed company compared to a guy in a truck

Re: Harnessing America's heat pump moment

#150

Post by sokoloff »

doctorhandshake wrote: post #108
Loughla wrote: post #101

Earlier quoted context omitted.

Define low temperatures. Mine struggles if it gets below 30, and might as well not exist below 10. They're not great at low temps.

I’m not sure what yours is but it doesn’t sound appropriate to your application. Mitsubishi hyper heat is indicative of a contemporary inverter design - 100% efficiency to -5f: https://www.mitsubishicomfort.com/articles/mythbusters-heat-...

100% efficiency is terrible for a heat pump. Electric resistance heat is 100% efficient.
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