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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

#121

Post by SECProto »

alkonaut wrote: post #120
SECProto wrote: post #63

Earlier quoted context omitted.

Note that a portion of that increase in gas consumption is still due to the hot water usage, even if the number and duration of showers stays the same - tap water varies in temperature through the year, getting colder in winter and warmer in summer. In my case, it varies between ~5 and ~22C. Germany has milder winter temperatures so likely not as much variation, but still a significant fraction of the temperature inc…

22 degrees is the coldest tap water? That means you basically need ice cubes or fridge storage before you can drink it in the summer?

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.

Re: Re-using the heat in bathwater in Britain

#122

Post by mvhvv »

sixstringtheory wrote: post #82

In addition to things like heat exchangers or reducing the amount of time/water in a shower, is there any work being done around optimizing the amount of time a hot water heater keeps the water at high temp? I’ve thought about this for extended absences but this could also bring potential benefits if it just doesn’t run for certain portions of the day or middle of the night.

I'm not sure if things are different outside Australia, but it's probably been 15-20 years since I've lived in a house with a hot-water storage tank. As far as I know most places seem to have instant/continuous systems that heat the water on demand as it passes through the line.

Solar-heating definitely makes storage make more sense, but I don't know how the numbers actually work out on that one.

Re: Re-using the heat in bathwater in Britain

#123

Post by SnaggyJoker »

TrueSlacker0 wrote: post #97
SnaggyJoker wrote: post #70

Earlier quoted context omitted.

You could also switch to a water conserving mist shower and reduce the amount of heated water used for the shower. You could also reclaim the water from the shower for use in the toilet by turning the supply to the toilet off and manually transferring it to the toilet tank. There are lots of things you could do to save resources but most things are not done and are not going to be done because it is inconvenient and…

Combo that with toilet sinks and a lot of water would/could be saved per year/person.

The same tank could be connected to the sink too, turning any toilet into a toilet sink.

Re: Re-using the heat in bathwater in Britain

#124

Post by thinkingemote »

wcoenen wrote: post #7

I tried this once on a cold winter day: I let the bath cool down to room temperature (which was <20C) before letting it drain, with the bathroom door open. The result was a lot of condensation on the windows in the surrounding rooms. I figured the high humidity was going to cause more damage than it saved money, so I scrapped the idea.

My smoke alarms go off.

Re: Re-using the heat in bathwater in Britain

#125

Post by Retric »

SECProto wrote: post #119
Retric wrote: post #114

Earlier quoted context omitted.

Well water stays very consistent year round in most areas. Some municipal systems vary more depending on where they get it and how they store it. Water towers used to smooth out water demand for example can noticeably impact water temperatures.

Temperature at the well stays consistent, but it can vary at the tap. At a family member's secondary property, tap water will vary from 2 deg in winter up to 15 in summer (because the line between the well and the house is only ~3-4 feet deep, and surface temperature changes a lot). If we were drawing more or less/line was different length/different depth, the variation would change. (I know all these values from hom…

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 water is unlikely to spend that long in these pipes to change temperature. Thus the ground temperature would need to be extremely different to make a significant difference once the temperature equalized.

Re: Re-using the heat in bathwater in Britain

#126

Post by alkonaut »

SECProto wrote: post #121
alkonaut wrote: post #120

Earlier quoted context omitted.

22 degrees is the coldest tap water? That means you basically need ice cubes or fridge storage before you can drink it in the summer?

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.

Re: Re-using the heat in bathwater in Britain

#127

Post by gima »

zubspace wrote: post #58
ArmandGrillet wrote: post #53

Tangentially related: has someone found something less energy intensive than taking a bath while bringing the same degree of warmth? I've been looking at heated blankets but they're all made of polyester which is not comfortable due to the moisture being trapped under the blanket. Heated seats in some cars are the closest sense of comfort I've found but that technology doesn't seem to exist for regular seats.

Maybe just one or two hot water bottles? [1] We use them in Winter to warm our feet in bed. But they are very versatile and can also be used to alleviate any kind of tension. I also use one while I code: I put it inside of a small (baby-)sleeping bag wrapped around my feet. Sounds weird, but it's so comfortable! [1] https://www.google.com/search?q=hot+water+bottle&tbm=isch

Another trick is to put lots of dry rice grains into a sock, tie the sock and warm it up in a microwave. Just be careful, as the rice heats up Really fast in the microwave.

Re: Re-using the heat in bathwater in Britain

#128

Post by divbzero »

I do a version of this when cooking without knowing if it actually has a significant effect: In summer I pour leftover hot water from cooking down the drain right after I finish, while in winter I leave the hot water sitting in the pot so the heat can warm the kitchen.

Re: Re-using the heat in bathwater in Britain

#129

Post by anigbrowl »

SnaggyJoker wrote: post #70
georgeg23 wrote: post #28

Earlier quoted context omitted.

You could place a plastic mat on top to limit evaporation.

You could also switch to a water conserving mist shower and reduce the amount of heated water used for the shower. You could also reclaim the water from the shower for use in the toilet by turning the supply to the toilet off and manually transferring it to the toilet tank. There are lots of things you could do to save resources but most things are not done and are not going to be done because it is inconvenient and…

Britain is not suffering a water shortage, nor is it likely to in any foreseeable future. Not that I'm encouraging people to waste water, but conserving water doesn't address the unfavorable economics of energy.

Re: Re-using the heat in bathwater in Britain

#130

Post by joe5150 »

SECProto wrote: post #121
alkonaut wrote: post #120

Earlier quoted context omitted.

22 degrees is the coldest tap water? That means you basically need ice cubes or fridge storage before you can drink it in the summer?

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.
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