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Re-using the heat in bathwater in Britain

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Re: Re-using the heat in bathwater in Britain

#141

Post by theGnuMe »

joe5150 wrote: post #130
SECProto wrote: post #121

Earlier quoted context omitted.

Strangely enough, drinking water is served at temperatures up to 100C in certain preparations (eg tea)! Less tongue in cheek, yes, people will often chill their tap water in the summer before drinking. But it's perfectly drinkable at whatever temperature it comes out of the tap. The water supply in my locality comes from a surface reservoir, leading to the higher summer temperatures.

In Arizona, "cold" water at the tap can easily be in the neighborhood of 100F/37C all summer. We kept a water filter pitcher in the fridge for drinking water, so it wasn't really a problem there, but it did make it impossible to take a truly cool shower or follow a recipe that instructs you to rinse something in cold water.

I grew up in AZ.. just run the water until it cools down. Unless your showering from an outside hose it'll be 50 degrees just from being underground. If you aren't getting that then something is very wrong with your plumbing I'd recon. Like, the tap intake comes into the house after the swap cooler on the roof kind of thing. Plus the evap after the shower.. that'll cool you off.

Re: Re-using the heat in bathwater in Britain

#142

Post by pbj1968 »

bausgwi678 wrote: post #24
yjftsjthsd-h wrote: post #10

Earlier quoted context omitted.

I've always experienced extremely low humidity in winter months, so I would think the net effect might be a reasonable positive if this saves me needing to run a humidifier. Am I missing some detail? Or is that just unusual?

It depends massively on your climate and how air in your house is managed. If you live somewhere which is significantly colder outside than in (e.g. 0-5C out, 21C inside) heating outside air to comfortable temperatures will greatly decrease humidity. Couple this with a system which circulates air, or even exchanges inside&outside air and you will have incredibly low humidity inside. I live somewhere which often sees…

Define “massively.” Sounds like a Reddit-esque waffle word like “wildly” or “dramatically.”

Re: Re-using the heat in bathwater in Britain

#143

Post by briHass »

anigbrowl wrote: post #136
SnaggyJoker wrote: post #131

Earlier quoted context omitted.

If they used less hot water they would use less energy heating the water. That was the original thought until I went off on the tangent about saving the hot water in a separate tank from the bathtub after it is "used" for the bath allowing the heat to be harvested and the water to be re-used. The original post is about leaving the hot water in the bath to use the energy to heat the house or help heat incoming water.…

I see your point but I am not sure about this. I suspect a lot of people use just as much water but spread it out longer. In California there are a lot of devices mandated to reduce consumer use (flow restrictors and so on), but interior water use often demands fixed quantities. For example if you want to have a bath rather than a shower then people will use the capacity of the tub, likewise if you boil water for coo…

As for the issues flushing large, ahem, amounts of waste with the low-water toilets, it's mostly just cliche now. When the restrictions were first added, the toilet manufacturers weren't ready. Probably a lot of the complaints were from experiences with these early models.

Now, low-flow toilets have an amazing amount of research and design put into how to meet the guidelines while still performing as well as, and often better than, old 4+ gallon flushes.

A few (ill-informed) complainers aside, this actually seems like a win all around. Toilets don't cost more than they used to, they use less water, and perform better than ever.

Re: Re-using the heat in bathwater in Britain

#144

Post by Baeocystin »

anigbrowl wrote: post #136
SnaggyJoker wrote: post #131

Earlier quoted context omitted.

If they used less hot water they would use less energy heating the water. That was the original thought until I went off on the tangent about saving the hot water in a separate tank from the bathtub after it is "used" for the bath allowing the heat to be harvested and the water to be re-used. The original post is about leaving the hot water in the bath to use the energy to heat the house or help heat incoming water.…

I see your point but I am not sure about this. I suspect a lot of people use just as much water but spread it out longer. In California there are a lot of devices mandated to reduce consumer use (flow restrictors and so on), but interior water use often demands fixed quantities. For example if you want to have a bath rather than a shower then people will use the capacity of the tub, likewise if you boil water for coo…

What California really needs to do is ban alfalfa farming for export. It is infuriating how much water goes to that crop alone for absolutely trivial amounts of return, compared to what the water consumed could have been used for. Water rights in the American West are an absolute cluster.

Re: Re-using the heat in bathwater in Britain

#145

Post by refurb »

alkonaut wrote: post #126
SECProto wrote: post #121

Earlier quoted context omitted.

Strangely enough, drinking water is served at temperatures up to 100C in certain preparations (eg tea)! Less tongue in cheek, yes, people will often chill their tap water in the summer before drinking. But it's perfectly drinkable at whatever temperature it comes out of the tap. The water supply in my locality comes from a surface reservoir, leading to the higher summer temperatures.

I just never reflected on the idea that cold tap water in summer is quite luxurious. I have that but I have no idea why tbh.

Indeed. Having living in SE Asia where you can drink the tap water, it’s rough getting a glass of water from the tap and it’s 25C.

There is no “cold” tap, just warm and hot taps.

Re: Re-using the heat in bathwater in Britain

#146

Post by diordiderot »

HPsquared wrote: post #54
yrgulation wrote: post #22

Energy poverty can be sorted out by better insulation and investment in cheaper and more sustainable sources such as nuclear, wind and solar. Instead of working around this issue with clever hacks this needs to be a national policy. I think all roofs should be mandated to have solar panels installed, as a start, and all new builds should have proper insulation.

If I was planning national energy infrastructure, I wouldn't plan on dividing the equipment into a million tiny pieces and installing it on roofs, of all places. It seems much simpler to manage a solar farm than 10,000 roofs.

Rooftop solar adds 'antifragility'

Re: Re-using the heat in bathwater in Britain

#147

Post by Retric »

SECProto wrote: post #133
Retric wrote: post #125

Earlier quoted context omitted.

Very rarely used property you can get temperature swings underground next to these pipes. But in normal domestic or municipal settings the regular water through the pipes is going to equalize temperatures year round to within a fraction of a degree at 3-4 feet underground outside of extremely long runs. Also of note, ~25feet of one inch pipe holds 1 gallon of water. So there can be quite a bit of lag involved, but wa…

The various municipalities I've lived in require 5 to 8 feet minimum bury depth for water pipes to avoid freezing. The seasonal property I mentioned earlier being at 3-4 feet depth is likely helped by the fact that snow is not cleared above the run (additional insulation) and it is in one of the milder climate areas where a municipal spec water run would only need 5 feet of bury. It may also have half inch of foam wr…

That’s likely overly cautious. https://www.hammerpedia.com/frost-line-map/

That said, municipality’s will often be overly cautious and they do need to consider property siting abandoned.

Re: Re-using the heat in bathwater in Britain

#148

Post by cameronh90 »

jtc331 wrote: post #137
cameronh90 wrote: post #51

Earlier quoted context omitted.

I'm in the UK, extra humidity is the last thing I'd ever want in winter. At the moment, I've got two beefy dehumidifiers running and I'm still at between 70-85% humidity in each room. I don't have any damp or leaks, it's just that the outdoor humidity has been 80-90% for the last few weeks, so ventilation is futile. And because of the weather at the moment, we're drying clothes indoors.

What is the temperature outside? Humidity is measured relatively (to how much water air can hold at the current temperature), so even 100% humidity outside at a moderately chilly temperature outside can still translate into uncomfortably dry (e.g., less than 35%) humidity inside.

Currently about 17c in the day, 14c at night. At the time of writing, outdoor is 13c and RH is 95%. It was 22c the other day, however it is quite unseasonably warm right now. Once it gets into proper winter weather, normal daytime climate is around 10c-ish and 80%-90% humidity. I've never seen my indoor humidity lower than about 50% without a dehumidifier except after a really long dry spell in the summer or a really cold day in winter.

It doesn't often get that cold here, just very damp. Global warming is making winters even wetter. The UK actually has a fair bit of "temperate rainforest" and is classed as a humid temperate oceanic climate.

Re: Re-using the heat in bathwater in Britain

#149

Post by fy20 »

jitl wrote: post #38

I read a lot about district heating systems yesterday after seeing an article on NYC's steam system on HN ( https://news.ycombinator.com/item?id=33388473 ). District heating systems allow you to capture waste heat at the power plant (called co-generation), and use that to heat & cool (via cooling compressors) many, many buildings at once. The wikipedia article about it is very informative as well: https://en.wikipedi…

I live in a post-Soviet country that has district heating systems, and rather quickly the demand for heat outstripped the demand for electricity, so in my city this is now mostly fulfilled by 'heat plants' burning gas. The price you pay per kWh of heat is quite a bit higher than you would pay for having a gas furnace or heat pump at home, so I'm not sure how efficient it is.

Also the heat plants are not that far from residential areas, so if they were to burn more polluting fuels (apparently when they were built, they burnt bunker fuel) it wouldn't really be any better than burning at the point of use.

If you have some kind of geothermal source (proper geothermal, not a ground source heat pump) it seems like it would make sense, but if not I think heat pumps at the point of use are a much better solution. In apartment blocks you could have a centralised system for the building, you don't need each unit to have its own system.

Re: Re-using the heat in bathwater in Britain

#150

Post by PragmaticPulp »

yrgulation wrote: post #22

Energy poverty can be sorted out by better insulation and investment in cheaper and more sustainable sources such as nuclear, wind and solar. Instead of working around this issue with clever hacks this needs to be a national policy. I think all roofs should be mandated to have solar panels installed, as a start, and all new builds should have proper insulation.

> I think all roofs should be mandated to have solar panels installed, as a start, and all new builds should have proper insulation.

I have good news for you: New construction has been required to have significant insulation in most jurisdictions for a very long time. The insulation requirements have steadily increased over the years, too.

States like California are already requiring new construction to have infrastructure to enable solar panel installation.

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