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The biggest heat pumps

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Re: The biggest heat pumps

#131

Post by cnewey »

OptionOfT wrote: post #121
cnewey wrote: post #88

Earlier quoted context omitted.

I was recently in a situation where I had to replace my oil-fired heating system’s oil tank (it wasn’t double skinned and no longer safe). It was £2500 to replace the oil tank, or I could opt for £2250 to install a heat pump with the government grant. This included all plumbing, electrical work, installation, and 6 new radiators all over my house. Honestly to me it seemed like a no-brainer. It’s a tad more expensive…

Did you add extra insulation to your house (or was it already more modern?). Otherwise the heatpump just can't catch up. And currently I have the opposite problem. The house is too well insulated for the heater (or the heater is too powerful). The heater only runs for a couple of minutes and huts off.

Hah, no my house was built in the 1750s or something like that - single glazing on the front and with fairly minimal insulation, plus it has no cavity wall (a mixture of wattle and daub and brick). It is a mid-terrace though so I benefit from neighbours being either side.

There have been a few cold snaps here where the weather has been down to -2 some days, but it’s been fine. I had a couple of minor installation issues (eg 3 way valve set incorrectly) but once those were fixed my house hasn’t dropped below 19C.

Re: The biggest heat pumps

#132

Post by fsckboy »

renhanxue wrote: post #97

Those are some big heatpumps, but in terms of installed capacity at a single location they have yet to beat the Stockholm municipal heating utility's installation at Hammarbyverket, which since its most recent expansion in 2013 has a total of 7 heat pumps capable of extracting up to 225 MW of heat energy from treated sewage. The utility claims it is (still) the world's largest heat pump installation. Notably it actua…

>energy from treated sewage

wouldn't untreated sewage, still fermenting, be warmer?

Re: The biggest heat pumps

#133

Post by fsckboy »

ahofmann wrote: post #20
kijin wrote: post #15

Earlier quoted context omitted.

Practically, the water would need to be somewhat warmer than 0℃ because you don't want it to freeze and clog the plumbing after you have extracted a useful amount of thermal energy. :)

Moving water will get much colder than 0℃ before turning solid. -10℃ or even -25℃ are easily possible. If the water is also under pressure, it can get even colder.

I thought to supercool water, it needed to be completely still? am i confusing it with superheating?

Re: The biggest heat pumps

#134

Post by ssl-3 »

Scoundreller wrote: post #126
ssl-3 wrote: post #119

Earlier quoted context omitted.

They are weird in the way that their utility varies. IIRC Dave Jones of EEVBlog fame has shown a air-to-water heat exchanger that he has at his home. It's outside. And the climate in Sydney is generally warm(ish), so it makes perfect sense there. I can also see them being useful in parts of the American South where big garages being common and the weather gets hot: Take some of the heat from the garage and convert it…

> I can also see them being useful in parts of the American South where big garages being common and the weather gets hot: Take some of the heat from the garage and convert it into hot water for showering and cleaning. Win-win. Uhhh, better to put the unit inside the home where it provides a bit of a/c. Double win if you cool the compressor with incoming water. Not in the south myself, but with trad water heaters, I…

Sure. It's better to start with an excellent home design that most-effectively uses every iota of modern tech to optimize efficiency. And sure, even more efficiency can be eeked out if one is willing to layer on their own productive infrastructure hacks.

But not everybody has those opportunities. Not every home has an existing conditioned space within which to put a water heater. Not every person is equipped (mentally or physically) to engineer and use tempering loops and/or water-cooling compressor motors.

As a practical matter: In a warm-climate home that already has a water heater in the garage (which is very common in the American south, from my limited direct observation), replacing a traditional water heater with one that uses a heat pump can make a lot of sense.

This replacement is something that any person and a friend with minimal plumbing and electrical experience can accomplish on their own in one afternoon, without incurring the expense and inconvenience of relocating their water heater somewhere else. There will be no drywall dust, and no paint.

It's a natural fit.

---

And don't take any of this the wrong way. You've got some great ideas there.

But not all environments are the same. During the warmer months in my own city, I've measured incoming water at 76F/24C -- warmer than the house, and also warmer than the basement where the plumbing lives. A tempering loop may make sense for you in your environment, but it would be the opposite of useful in my environment: "Oh neat! A thing that makes my home harder to cool in the summer!" (Unusual? Perhaps. But it's my reality anyway. I've never run out of hot water in this city during the summer. Not even close. But things do change in the winter -- maybe I'll measure the input temperature again when I get home tonight.)

It's fun to think about niche concepts that don't have broad-scale adoption. And sometimes, it makes sense to set forth and make them a reality.

But it's always important to remember that there's often very real reasons for them to remain niche concepts that aren't broadly utilized.

Re: The biggest heat pumps

#135

Post by renhanxue »

fsckboy wrote: post #132
renhanxue wrote: post #97

Those are some big heatpumps, but in terms of installed capacity at a single location they have yet to beat the Stockholm municipal heating utility's installation at Hammarbyverket, which since its most recent expansion in 2013 has a total of 7 heat pumps capable of extracting up to 225 MW of heat energy from treated sewage. The utility claims it is (still) the world's largest heat pump installation. Notably it actua…

> energy from treated sewage wouldn't untreated sewage, still fermenting, be warmer?

Maybe. I guess it's easier to handle in treated form though. At the point where it gets to the facility it's actually not really sewage anymore, it's just clean water, so after passing the heat pumps it's just released into a nearby lake via a small turbine (both the sewage treatment plant and the heating plant ar located above the water level of the lake).

Re: The biggest heat pumps

#136

Post by tzs »

jgalt212 wrote: post #87
willvarfar wrote: post #14

In the nordics we love heat-pumps! Something like 70% of houses are heated by heat-pumps, and 90% of apartment buildings are heated by district heating and that is often generated by huge heatpumps. Apparently 95% of new heating installations in Swedish houses are heat-pumps these days: https://publications.jrc.ec.europa.eu/repository/handle/JRC1... Heatpumps have been heating nordic homes for decades. Even in the co…

> Something like 70% of houses are heated by heat-pumps To me, living in US Northeast, this is astounding. I've read heat pumps lose efficacy below 25F. My family would never forgive me if I made our house cold. But then I see 70% of the Nordics's house are "warm enough", or dealing colder than room temperature houses. I've asked half-dozen contractors and HVAC people in my area, and none of them have recommended a h…

That's old heat pumps. Mitsubishi introduced their "Hyper-Heating Inverter" heat pumps designed to work well in cold weather in 2007, with Fujitsu and Daikin adopting similar technology by 2012, and others following within a few years.

These remain 200% efficient down to -4℉ and 150% efficient down to -22℉. Their capacity starts dropping at 23℉ going down to 76% capacity at -13℉.

There's only a few towns in the continental US that cold enough for long enough that it can't be heated well by one of these. You just need an installer that will size it properly for the climate in your area.

Re: The biggest heat pumps

#137

Post by dzhiurgis »

jimmaswell wrote: post #92
xg15 wrote: post #85

A bit OT, but since this article also mentions district heating: Are there any efforts to attach any of the recently built AI data centers (and their power plants) to district heating networks?

If we all went full-in on nuclear we could use resistive heat and air cool datacenters all day with no concern for the cost. It's a shame.

We couldn't since all the capacity would go to AI, not to your home heating.

Re: The biggest heat pumps

#138

Post by triceratops »

lnsru wrote: post #38
moooo99 wrote: post #28

Earlier quoted context omitted.

As a German, I find the popularity of heat pumps in the nordics especially amusing. In Germany heat pumps were an incredibly political topic and people were pushed by some media outlets to really hate heat pumps. One recurring topic was that heat pumps can‘t work at German temperatures.

Nothing amusing. Germany is not really rich compared to nordics. And now let‘s do so math! Electricity: 0,3€/kWh and gas 0,1€/kWh. I need ~3x more gas to get same temperature in my room. And gas heating costs €10k while heat pump €40k without subsidies and probably raw €15k material cost if I install it by myself. So why should I pay more by €30k to install experimental thing for a decade when my low cost gas heating…

€40k for a heat pump is insane. Even just the parts for €15k is unbelievable. Do you have a source?

Re: The biggest heat pumps

#139

Post by fy20 »

OptionOfT wrote: post #120
willvarfar wrote: post #14

In the nordics we love heat-pumps! Something like 70% of houses are heated by heat-pumps, and 90% of apartment buildings are heated by district heating and that is often generated by huge heatpumps. Apparently 95% of new heating installations in Swedish houses are heat-pumps these days: https://publications.jrc.ec.europa.eu/repository/handle/JRC1... Heatpumps have been heating nordic homes for decades. Even in the co…

Interesting that district heating is so popular there. IIRC in the Netherlands people don't like it, because it because it means that there is a single company supplying my heat, with * minimum amounts of 'heat' purchased * no incentives to maintain their infrastructure above the bare minimum * no competition

I live in a post-Soviet city with district heating, and I'm not really sure it's worth it. Our network is government run, and they don't do a bad job, but it is more expensive per kWh (8c) than if you were to heat with gas or an electric heat pump (both 6c).

The heat source of the network is gas or various oil fuels, so it makes sense that it's cheaper to do it yourself - gas infrastructure is very optimised, and there are very little network losses in comparison. I think it only makes sense if the network has a cheap energy source, for example by using waste energy from industrial processes or utility-scale geothermal.

Re: The biggest heat pumps

#140

Post by stephen_g »

ssl-3 wrote: post #119
PaulDavisThe1st wrote: post #117

Earlier quoted context omitted.

> air-to-water heat pumps these are slightly odd, however: they either need an external air intake set up, or they require that the water (tank/heater) be located in a space that you don't mind being cooled down (often quite significantly) AND that isn't thermally connected to the space you're heating via other means. still great technology, but deployment can be a little more challenging that space heating/cooling.

They are weird in the way that their utility varies. IIRC Dave Jones of EEVBlog fame has shown a air-to-water heat exchanger that he has at his home. It's outside. And the climate in Sydney is generally warm(ish), so it makes perfect sense there. I can also see them being useful in parts of the American South where big garages being common and the weather gets hot: Take some of the heat from the garage and convert it…

I have the same air to water heat pump HWS that Dave has - it's a split system so you can put the tank inside the basement and the heat pump outside. You just need to run two insulated water pipes between them and a temperature probe cable. There are of course systems where the heat pump is attached directly on top of the tank but lots are split. They should easily work at -10 °C so no issue having the heat pump outside.
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