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Thermoelectric heating stands at the brink of commercialization

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Re: Thermoelectric heating stands at the brink of commercialization

#91

Post by dcuthbertson »

stetrain wrote: post #88
pjc50 wrote: post #67

Earlier quoted context omitted.

Replacing like for like should be a fairly easy job. But replacing between different systems does seem to be a nightmare. It's interesting that Americans are retrofitting them into HVAC systems, while in the UK we're trying to retrofit into natgas/water based systems, and seemingly the Scandinavians have gone for .. I'm not sure but it seems cheaper? I upgraded to a "hybrid" system because it was the least cost / min…

It's fairly common in the US to have central AC plus a gas furnace. Retrofitting the AC with a heat pump lets you move away from the gas system.

Replacing an AC system with a heat pump might provide you with an avenue to move away from a gas furnace, but I found that avenue to be very expensive. I live in New England and in June 2022 I replaced a broken down AC system with a heat pump. The company installed an electric supplemental heating unit, because the heat pump can work down to only 25F (about -4C) and during Winter it will definitely get colder than that. However, last Winter cost me about $800 more than any previous Winter here (I've lived in the same house in New England for the past 33 years).

After a pipe burst in the baseboard heating system (because it wasn't running, it was only -10F outside, and the pipe passed through a poorly insulated area of the house), I had the HVAC company rewire the system to use the gas-fired, forced hot water baseboard system as the backup. I look forward to much lower heating costs this Winter.

Re: Thermoelectric heating stands at the brink of commercialization

#92

Post by khimaros »

kwhitefoot wrote: post #85
pjc50 wrote: post #67

Earlier quoted context omitted.

Replacing like for like should be a fairly easy job. But replacing between different systems does seem to be a nightmare. It's interesting that Americans are retrofitting them into HVAC systems, while in the UK we're trying to retrofit into natgas/water based systems, and seemingly the Scandinavians have gone for .. I'm not sure but it seems cheaper? I upgraded to a "hybrid" system because it was the least cost / min…

In Scandinavia we use air to air heat pumps. We generally don't have central heating of any kind so we aren't so tempted to try to shoehorn the heat pump into a system based on hot water. Air to air is much cheaper and is more efficient because it doesn't need to raise the temperature of the working fluid so much and doesn't require a big fluid to water heat exchanger. I'm having a Toshiba Polar 35 heat pump installe…

which refrigerant is used in this?

Re: Thermoelectric heating stands at the brink of commercialization

#93

Post by naasking »

c_o_n_v_e_x wrote: post #55
bilsbie wrote: post #4

I’d pay a premium for a solid state AC or heat pump. It’s absurd how much they cost to install. And I don’t get why replacing one is an all day job for three people. There should be standard connections they just plug into. Like a dishwasher.

>And I don’t get why replacing one is an all day job for three people. Let's go through the whole process. You need a system changeout for a ducted central HVAC system. Someone comes over and gives a bid. You accept. Your HVAC person needs to go to a supply house and purchase all of the parts and bring them to your residence in a vehicle than can hold everything. Assuming you have an existing system, the refrigerant…

This is a good overview explaining why it's an all-day job, but doesn't explain why it requires 3 people (if that's true). Only moving the equipment in and out is helped by having more than 1 person.

Re: Thermoelectric heating stands at the brink of commercialization

#94

Post by Scoundreller »

leoedin wrote: post #90
Scoundreller wrote: post #33

Earlier quoted context omitted.

I want a cottage industry of aluminum smelters in cold climates. Pick up a pile of aluminum oxide from a depot, electrolyze it into aluminum at home, and drop off the finished aluminum at the depot for a cheque that covers your electricity. "The theoretical minimum energy requirement for this process is 6.23 kWh/(kg of Al), but the process commonly requires 15.37 kWh." https://en.wikipedia.org/wiki/Hall%E2%80%93H%C3%…

The problem is that heat pumps exist, so resistive heating is never the best option. An aluminium smelting at home heating solution would have a maximum CoP of 2 (as you're reducing the energy usage of the smelter by the same amount). A heat pump could easily have a CoP of 3 or 4.

That’s a lot more efficient than an industrial aluminum smelter.

The use of electricity as an input is inescapable for this process, so may as well use the waste heat as directly as possible.

Re: Thermoelectric heating stands at the brink of commercialization

#95

Post by Workaccount2 »

elil17 wrote: post #83

As someone who works in this industry - no, thermoelectric heating does not stand at the brink of commercialization. The fundamental issue with thermoelectric heating is that you need a material with high electrical conductivity but very low thermal conductivity. zT is a metric that measures this ratio. Conducting electricity but not heat is a weird property for a material to have and no one even knows if zT can be r…

I don't understand why they would even consider it for heating? An electric heater is already 99.99% efficient.

Re: Thermoelectric heating stands at the brink of commercialization

#96

Post by amluto »

Workaccount2 wrote: post #95
elil17 wrote: post #83

As someone who works in this industry - no, thermoelectric heating does not stand at the brink of commercialization. The fundamental issue with thermoelectric heating is that you need a material with high electrical conductivity but very low thermal conductivity. zT is a metric that measures this ratio. Conducting electricity but not heat is a weird property for a material to have and no one even knows if zT can be r…

I don't understand why they would even consider it for heating? An electric heater is already 99.99% efficient.

By that standard, a heat pump is something like 400% efficient (it depends on a lot of factors), and replacing an electric heater with a heat pump pays for itself quite quickly if you’re using it to heat an entire house or even a poorly insulated room.

Re: Thermoelectric heating stands at the brink of commercialization

#97

Post by amluto »

hijinks wrote: post #22
bilsbie wrote: post #4

I’d pay a premium for a solid state AC or heat pump. It’s absurd how much they cost to install. And I don’t get why replacing one is an all day job for three people. There should be standard connections they just plug into. Like a dishwasher.

I was quoted 10k a head unit to install mini-splits in a home in the colorado mountains. I needed 8 head units. It was nothing but "only rich people are buying these right now so lets cash in" pricing

Find another contractor. I got three heads in the Bay Area for around $8500 total. The only caveat was that this didn’t include patching the walls.

Re: Thermoelectric heating stands at the brink of commercialization

#98

Post by amluto »

bilsbie wrote: post #4

I’d pay a premium for a solid state AC or heat pump. It’s absurd how much they cost to install. And I don’t get why replacing one is an all day job for three people. There should be standard connections they just plug into. Like a dishwasher.

A dishwasher is a single object. A heat pump has an indoor part, and outdoor part, and (at least) two tubes between them. Those tubes can carry one of several refrigerants (with attendant oil contamination), water, or glycol solutions. Or occasionally air. There are quite a few standards for connecting all of these, although the standards for air appear to literally be duct tape [0] or sticky goop called mastic. And refrigerant, which is the most common choice, is under high pressure and needs special handling.

[0] I mean real duct tape: the UL181 stuff. The world is full of kinds of tape, and many of them are excellent. I’ve never seen anything I would call excellent duct tape. It doesn’t conform well to irregularities, and it doesn’t seem to have anywhere near the stretchiness required to actually seal the inherently curved gap between round ducts.

Re: Thermoelectric heating stands at the brink of commercialization

#99

Post by amluto »

kwhitefoot wrote: post #85
pjc50 wrote: post #67

Earlier quoted context omitted.

Replacing like for like should be a fairly easy job. But replacing between different systems does seem to be a nightmare. It's interesting that Americans are retrofitting them into HVAC systems, while in the UK we're trying to retrofit into natgas/water based systems, and seemingly the Scandinavians have gone for .. I'm not sure but it seems cheaper? I upgraded to a "hybrid" system because it was the least cost / min…

In Scandinavia we use air to air heat pumps. We generally don't have central heating of any kind so we aren't so tempted to try to shoehorn the heat pump into a system based on hot water. Air to air is much cheaper and is more efficient because it doesn't need to raise the temperature of the working fluid so much and doesn't require a big fluid to water heat exchanger. I'm having a Toshiba Polar 35 heat pump installe…

Do mean air-to-refrigerant-to-air or do you literally mean a big box with ducts coming out? The latter is called a “packaged terminal” heat pump in the US, and they haven’t really caught on except in cheap hotels.

Re: Thermoelectric heating stands at the brink of commercialization

#100

Post by at_a_remove »

thsksbd wrote: post #53
UI_at_80x24 wrote: post #23

Earlier quoted context omitted.

Heating with a wood stove doesn't really have a 'medium' setting. You get 100% while it's roaring away, and that slowly diminishes as the fuel burns down. (Yes you can adjust dampers, and air-flow valves to "slow it down"; but that doesn't really work/happen.) I've lived in a home heated by a wood stove for 10 years. You would build-up the stove so it blasts away, goto bed, and by morning there would be enough coals…

Or you do what slavs did for century and build a massive mud oven to trap the heat in.

Better yet, bring back Feolite for ridiculous heat capacity in Calories per gram.
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