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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

#231

Post by _nalply »

mnw21cam wrote: post #230
_nalply wrote: post #221

You shouldn't let warm water stay in a place with air contact. First it makes air humid and the affected rooms prone to mold, and second evaporation takes energy away, and while condensation might give the energy back you will have wet conditions. It's not very sanitary: warm and wet conditions for some time tend to encourage unwanted life. I armchair thought about a scheme: collect the bath and shower water in a tan…

I have been considering a grey water solution that would achieve two things. The bath in my house is upstairs, and I have an additional toilet downstairs, almost directly underneath. So, I could let the bathwater drain into a tank above the toilet cistern, from where it can slowly release its heat, and then use the water to fill the toilet cistern for flushing. That way, I save on heating and on water usage, and the…

That's a clever solution.

In a different vein, I thought about dismantling the mobile air conditioner and putting it in a cold water bath instead sucking air to heat to blow to outside. The lower part is wet anyway from condensate.

This summer I did something different and simpler: instead of a hose to outside, I made a wooden frame fitting into the window and strapped the air conditioner to it such that it sucked the air from outside instead from inside. I think it worked better this way because it didn't create negative pressure in the flat anymore and because it could blow the hot waste air directly to the outside. The fans didn't need to fight against the negative pressure and the long hose.

Re: Re-using the heat in bathwater in Britain

#232

Post by netsharc »

SnaggyJoker wrote: post #180
zarzavat wrote: post #176

Earlier quoted context omitted.

The problem is how to keep such a system clean, as then there will be a bunch of foreign gunk floating around in your cistern.

Yeah and bacteria would build up in the reserve tank. An inline filter of some sort could be used for particles but that would require maintenance. There would also be soap scum build up and hair conditioner products would gunk up the works I'm sure.

In Japan they don't seem to have a problem to put a sink (for handwashing) that drains to the reserve tank:

https://imgcp.aacdn.jp/img-a/1200/auto/global-aaj-front/arti...

Re: Re-using the heat in bathwater in Britain

#233

Post by redtexture »

cameronh90 wrote: post #148
jtc331 wrote: post #137

Earlier quoted context omitted.

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…

What region of the UK are you located in?

Re: Re-using the heat in bathwater in Britain

#234

Post by mahathu »

chihuahua wrote: post #116
tempestn wrote: post #109

Problem is you're not just adding heat, but humidity. Normally while having a shower you're going to run an exhaust fan in the bathroom. So if you want to conserve heat, the better approach is just to make the shower as short as possible.

That seems like a more realistic suggestion to me. If you want to take this further, switch to taking Navy showers: get wet, turn off shower, apply soap, turn on shower to rinse off.

>get wet, turn off shower, apply soap, turn on shower to rinse off.

Isn't that just a regular shower?

Re: Re-using the heat in bathwater in Britain

#235

Post by Retric »

robertlagrant wrote: post #215
Retric wrote: post #165

Earlier quoted context omitted.

I agree water temperature at the tap can vary quite a bit. My parents place has the water go through an unheated crawl space and they would regularly keep the tap on to avoid the pipes freezing when temperatures got unusually cold. Further many municipalities extract water from rivers which experience significant seasonal variation etc. My comment was simply in reference to well water which has very consistent temper…

The original point was that a shower would have to use more energy to heat shower water in winter. Not sure now how any of your comments relate to that - do you agree with it?

The relationship is many people don’t experience that. Aka it’s a you might experience X not a you will experience X.

A poster mentioned failing to get a cold shower in Singapore, but Singapores ground temperatures are much higher than we are used so well water is going to be ~25C year round and tap water can be significantly warmer than that.

Re: Re-using the heat in bathwater in Britain

#236

Post by redtexture »

hkt wrote: post #217
Maxion wrote: post #207

Earlier quoted context omitted.

House code in Finland requires mechanical ventilation with vents in the bathroom. I only see brief condensation on my bathroom windows when I leave the sauna door open in the winter (approx. 100 celsius, 80%RH). With good building codes, you won't have condensation issues.

Alas, the UK has the twin problems of poor building codes and lots of old housing stock that nobody puts much thought into maintaining. In the latter case, people will take single skin brick buildings and apply "vapour control" materials outside the building, thus ensuring moisture is locked into the bricks. Then they wonder why they have damp, etc. Alas, we are a very silly country.

What kinds of material is added to exterior brick? Insulating panels?

Re: Re-using the heat in bathwater in Britain

#237

Post by heavenlyblue »

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.

> Strangely enough, drinking water is served at temperatures up to 100C in certain preparations (eg tea)!

It's prepared at 100C, and _may_ be served at 100C, but it does not enter your body at 100C or you will burn your mouth.

> 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.

It may be drinkable, but temperatures above 25C will be a cesspit for legionella.

Re: Re-using the heat in bathwater in Britain

#238

Post by VBprogrammer »

spockz wrote: post #37
VBprogrammer wrote: post #27

Earlier quoted context omitted.

I think a step further is required. I really like the idea of using solar panels as an integral part of the roofing structure. There are people in the UK doing this as integrated solar panels which use a plastic tray underneath. I think with some slight adaptions we could even do better.

We had a few of these projects in the Netherlands. It is nice, until it isn’t. The solar panels are more vulnerable than tiles, they will degrade or need repairs/replacing. The mechanism for sealing it up will leak. The format of the panels and or the inverter was proprietary. Or the connection was and you couldn’t retrofit another inverter. It wasn’t a good experience.

Sounds like there are a few things being mixed in there. I'm not really that convinced that solar panels are any more subject to damage than they would otherwise be. Maybe you gain a little in terms leak proofing by having a normal roof underneath but it's a lot of material for a marginal gain. Typically roofs these days are constructed with an impermeable plastic sheeting which is waterproof in its own right but requires protection from the elements (particularly the sun).

It's impressive that they managed to make a DC electrical connection proprietary though!

Re: Re-using the heat in bathwater in Britain

#239

Post by cameronh90 »

redtexture wrote: post #233
cameronh90 wrote: post #148

Earlier quoted context omitted.

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…

What region of the UK are you located in?

Inner London, which is going through a bit of a damp period right now after a really dry summer. I'm not sure if those two things are related, but technically we are still in drought even though my garden is basically a swamp right now.

My tropical plants are enjoying it though.

Re: Re-using the heat in bathwater in Britain

#240

Post by theGnuMe »

kortilla wrote: post #156
theGnuMe wrote: post #141

Earlier quoted context omitted.

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.

Cap water is recharged into the groundwater aquifers.

Also you’ll notice no water towers.

And it’s Tucson… not Tuscon.

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