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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

#61

Post by michal8181 »

skrause wrote: post #55
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.

Living in Germany and getting both my heating and hot water from natural gas I regulary track my gas consumption throughout the different seasons. With 1-2 showers per day in the household my daily natural gas consumption in winter is about 20x higher than in summer, so compared to heating the house the energy in the hot water is a drop in the bucket.

Same here (I live in Poland). 2 + 2 family with small kids. Hot water is 5% of my overall gas bills. Rest is heating.

Re: Re-using the heat in bathwater in Britain

#62

Post by yrgulation »

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.

Why not both tho? Energy issues arent limited to capture and storage, it involves distribution as well. Plus you want energy to be dirt cheap and accessible. So the more the better.

Re: Re-using the heat in bathwater in Britain

#63

Post by SECProto »

skrause wrote: post #55
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.

Living in Germany and getting both my heating and hot water from natural gas I regulary track my gas consumption throughout the different seasons. With 1-2 showers per day in the household my daily natural gas consumption in winter is about 20x higher than in summer, so compared to heating the house the energy in the hot water is a drop in the bucket.

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 increase imparted by your water boiler. Additionally, if you have a hot water tank (as opposed to on demand), then the tank has to work harder to maintain temperature (assuming you maintain the indoor air temperature differently in winter than summer).

All combined, that might account for a 2 to 3 fold increase, the rest of it would be caused by space heating.

Re: Re-using the heat in bathwater in Britain

#66

Post by louison11 »

Where we live in Portugal humidity is a big problem, and we actually spend 1kW 24/7 running dehumidifier throughout the house. If we didn’t, mold would grow and we would get severe allergies. So… this seems like a very bad idea even for the UK, considering it’s very rainy there in the winter.

Re: Re-using the heat in bathwater in Britain

#67

Post by lkramer »

In my experience, there a many lower hanging fruits in British houses to save energy than this. Uninsulated and draughty old houses seems to be the norm here (at least if you're renting).

I'm surprised the government is not pursuing this more aggressively.

Re: Re-using the heat in bathwater in Britain

#68

Post by mgaunard »

lkramer wrote: post #67

In my experience, there a many lower hanging fruits in British houses to save energy than this. Uninsulated and draughty old houses seems to be the norm here (at least if you're renting). I'm surprised the government is not pursuing this more aggressively.

Even if you're buying, the most popular houses are ancient Victorian ones which, in spite of their charm, are very badly insulated.

They're often listed and require fitted wooden windows, so it's not exactly easy to fix.

Re: Re-using the heat in bathwater in Britain

#69

Post by upsidesinclude »

Turning your thermostat down by one or two degrees per week and getting acclamation to cold is a better alternative. 5 degrees on the thermostat would be a far better measure than tub heat.

Short showers, or 'sea showers', to conserve water and heating would likewise be a far better option than a 50 gallon bath.

Re: Re-using the heat in bathwater in Britain

#70

Post by SnaggyJoker »

georgeg23 wrote: post #28
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.

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 takes time, and time is money.

Edit: now that you have me thinking about this idea, it would be possible to have a container in the bathroom attached to a plug that has a hand pump and a tube going to the drain that could be used to reclaim and hold the water that could be higher than the toilet supply and the pressure from it could be used to have it self fill the toilet tank. The container could be highly conductive material like stainless steel and it could be relatively sealed to avoid humidity issues. This would of course be a vector for illness in some cases.

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