Re-using the heat in bathwater in Britain • Hacker News Board

Re: Re-using the heat in bathwater in Britain

#151

Post by SECProto » Mon, Oct 31, 2022, 2:00 AM UTC

Retric wrote: post #147

SECProto wrote: post #133

Earlier quoted context omitted.

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.

> That’s likely overly cautious

I'm not in the country shown on your map. The area of Canada I'm in would be somewhere roughly around the 90" line on that map. It's between the 2000 and 2500 lines on this map [1] (the seasonal property is around a 1500 contour)

The municipalities pay for the main to be installed. They wouldn't spec it to be 8' (2.4m) deep if it didn't need to be.

edit: the contours in my source are not mm of freezing depth, but degree-days of freezing. However, 2500 DDOF corresponds[2] with 70" of frost penetration, while the 1500 DDOF corresponds with 55". So the required bury depths are slightly but not significantly conservative

[1] https://www.urecon.com/applications/images/canadian_map_lrg....

[2] 1962 source: https://nrc-publications.canada.ca/eng/view/ft/?id=15f6f5eb-...

Re: Re-using the heat in bathwater in Britain

#152

Post by roenxi » Mon, Oct 31, 2022, 2:09 AM UTC

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…

> 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 takes time, and time is money.

This is radically underselling how much most people are willing to do for 50 pounds. If people are being squeezed out of their lifestyle due to energy costs (which seems quite likely, looking at the aggregate stats) they'd spend the time to conserve energy. Assuming someone shows them how to do it.

It remains a mystery why everyone was so calm walking in to this while tightening the screws on fossil fuel industries to stop them investing int he future. The globe needed a supportive regulatory environment for more nuclear power 20 years ago. Now there appears to be a global crisis in progress.

Re: Re-using the heat in bathwater in Britain

#153

Post by intelVISA » Mon, Oct 31, 2022, 2:14 AM UTC

mrshadowgoose wrote: post #132

ytdytvhxgydvhh wrote: post #80

I appreciate this attitude: > Should you do this? > I render no judgment! > But here’s a thought: It’s OK to use energy for convenience. This is true even in a time of crisis. After all, only a small fraction of the energy we use is necessary to stay alive. We could live dirty and shivering in dark rooms, eating oats and only moving around on foot. But no one does. So the question is how much energy you want to use f…

I couldn't agree more. That type of sentiment is pervasive, and it's absolutely baffling, because we as a society can keep all our excesses and comforts while making the consequential energy expenditures completely green. It seems like people are just incapable of conceiving of solutions that don't involve morally shaming others into being less happy. Or a more cynical take: It seems like a lot of people enjoy "solut…

I won't be needlessly wasteful but I'm not going to inconvenience myself over a corporation's marketing dept. trying to avail its company's tremendous carbon footprint.

Re: Re-using the heat in bathwater in Britain

#154

Post by SECProto » Mon, Oct 31, 2022, 2:16 AM UTC

theGnuMe wrote: post #141

joe5150 wrote: post #130

Earlier quoted context omitted.

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.

You sure it'll be 50 deg? that's significantly colder than summer tap water in my Canadian city, which is closer to 70F at peak.

Re: Re-using the heat in bathwater in Britain

#155

Post by aaron695 » Mon, Oct 31, 2022, 2:20 AM UTC

Put on a hot heater when taking a shower.

In theory you'll turn the water heat down which stops a lot of loss, 1 kg air is ~1000 liters, 1 kg water is 1 liter. It'll also flow back into the house.

And I get out sooner because it's not scary outside.

This person has installed two drain-water heat recovery systems, and measured it https://www.tiktok.com/@johnsavesenergy/video/70465726671214... This is the proper way forward.

Re: Re-using the heat in bathwater in Britain

#156

Post by kortilla » Mon, Oct 31, 2022, 2:20 AM UTC

theGnuMe wrote: post #141

joe5150 wrote: post #130

Earlier quoted context omitted.

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.

Not sure where you grew up, but most of the population gets tap water from the CAP, which means the water ran for hundreds of miles in canals across the desert before going into a water treatment plant. It’s 90F+ easily in the summer in any modern builds in Tuscon/Phoenix.

Re: Re-using the heat in bathwater in Britain

#157

Post by vkou » Mon, Oct 31, 2022, 2:26 AM UTC

roenxi wrote: post #152

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…

> 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 takes time, and time is money. This is radically underselling how much most people are willing to do for 50 pounds. If people are being squeezed out of their lifestyle due to energy costs (which seems quite likely, looking at the aggregate stats) they'd spend the time to c…

> It remains a mystery why everyone was so calm walking in to this while tightening the screws on fossil fuel industries to stop them investing int he future.

Because the only half-solutions we got for mitigating climate change were drafted by people who are largely free market types, and they can only envision free market solutions - which require end users figuring out how they are going to deal with more expensive energy on their own.

That does, of course, result in quite a bit of pain along the way.

Re: Re-using the heat in bathwater in Britain

#158

Post by Retric » Mon, Oct 31, 2022, 2:26 AM UTC

SECProto wrote: post #151

Retric wrote: post #147

Earlier quoted context omitted.

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.

> That’s likely overly cautious I'm not in the country shown on your map. The area of Canada I'm in would be somewhere roughly around the 90" line on that map. It's between the 2000 and 2500 lines on this map [1] (the seasonal property is around a 1500 contour) The municipalities pay for the main to be installed. They wouldn't spec it to be 8' (2.4m) deep if it didn't need to be. edit: the contours in my source are n…

I agree they need to bury it nearly that depth but while IPC 2018 section 305.4 puts water pipes at least six inches below the frost line many places increase that to 12” for water and or sewer.

I don’t know much about how Canada does things.

Re: Re-using the heat in bathwater in Britain

#159

Post by godelski » Mon, Oct 31, 2022, 2:35 AM UTC

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…

I'm very confused at the lash back you're getting. Have you all never seen the pipes freeze? Or worse: burst? They wouldn't do that if they didn't swing in temperature. I'm not convinced of SEC's 2-3x estimated increase but the claim that water temperature delivered to your taps vary in temperature is an objective fact. Of course different areas have different infrastructure and can be more resistant to freezing and rupture, but turn on the cold water in the dead of winter and you'll find it is a lot colder than in summer.

Re: Re-using the heat in bathwater in Britain

#160

Post by hedora » Mon, Oct 31, 2022, 2:58 AM UTC

mrshadowgoose wrote: post #132

ytdytvhxgydvhh wrote: post #80

I appreciate this attitude: > Should you do this? > I render no judgment! > But here’s a thought: It’s OK to use energy for convenience. This is true even in a time of crisis. After all, only a small fraction of the energy we use is necessary to stay alive. We could live dirty and shivering in dark rooms, eating oats and only moving around on foot. But no one does. So the question is how much energy you want to use f…

I couldn't agree more. That type of sentiment is pervasive, and it's absolutely baffling, because we as a society can keep all our excesses and comforts while making the consequential energy expenditures completely green. It seems like people are just incapable of conceiving of solutions that don't involve morally shaming others into being less happy. Or a more cynical take: It seems like a lot of people enjoy "solut…

I totally agree. However, if you have the means to spend a bit more on appliances (with payoffs 5-10 years out), then you can easily reduce energy / water (ignoring grass/crops) usage by about 75% vs 10-20 years ago with zero lifestyle impact.

Not doing that is needlessly wasteful.

In the particular case of showers, get a High Sierra shower head. They have more apparent flow / pressure than a full flow one, but use a small fraction of the water. They cost under $50 and are extremely reliable. (Never had one clog, and never did any maintenance on one, even with extremely hard water.)

The article estimates scavenging the bath water heat would reduce total energy consumption by 1.2%. This is much better achieved by lowering the thermostat, or showering less often in the winter. (Or buying a low flow showerhead -- see above!)

Note: No affiliation with High Sierra. Happy customer for a decade, across multiple homes. We currently have a 1.5 GPM, but I throttle it down with the trickle valve. The 1.25 GPM is totally fine; the trickle valve might make sense for it too. Note that you can customize colors, etc:

https://www.highsierrashowerheads.com/shop/classic/