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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

#131

Post by SnaggyJoker »

anigbrowl wrote: post #129
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…

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.

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. The idea of an external tank made out of conductive material would eliminate some of the problems and also allow the water to be re-used for the toilet.

Re: Re-using the heat in bathwater in Britain

#132

Post by mrshadowgoose »

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 "solutions" that stick-it to some other part of the population.

"That shower you enjoy uses too much water, you should take shorter and weaker showers." "Shame on you for flying to see your distant relatives, you should take fewer flights." "How dare you use a comfortable car to get around? Unless you're unhappy in a bus with at least 10 other people, you're a bad person."

Without even considering other sources of green energy, there is more than enough solar energy reaching the Earth to allow all 8 billion of us to enjoy consumption levels typical of Western nations.

Re: Re-using the heat in bathwater in Britain

#133

Post by SECProto »

Retric wrote: post #125
SECProto wrote: post #119

Earlier quoted context omitted.

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 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 wrap for insulation, I'm not sure.

Agree on the pipe volumes.

Re: Re-using the heat in bathwater in Britain

#134

Post by nly »

anigbrowl wrote: post #129
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…

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.

Hosepipe bans are pretty common in the UK due to water shortages

Re: Re-using the heat in bathwater in Britain

#135

Post by anigbrowl »

nly wrote: post #134
anigbrowl wrote: post #129

Earlier quoted context omitted.

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.

Hosepipe bans are pretty common in the UK due to water shortages

I think that has more to do with under-investment in infrastructure. Britain does have recurring droughts but they're pretty shallow.

Re: Re-using the heat in bathwater in Britain

#136

Post by anigbrowl »

SnaggyJoker wrote: post #131
anigbrowl wrote: post #129

Earlier quoted context omitted.

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.

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 cooking a flow restrictor just means it takes longer to fill the pot to the required level. So people use just as much but just suffer lower pressure.

Toilet cisterns arguably do reduce usage but then many people complain about less effective flushing which requires additional water; I don't have data to know if these objections are just a cliche or reflect an actual problem. My understanding is that lawn-watering is the biggest waste of water by consumers, to the point that some local authorities will subsidize people reorganizing their gardens to be more suitable for a dry climate.

Re: Re-using the heat in bathwater in Britain

#137

Post by jtc331 »

cameronh90 wrote: post #51
Someone1234 wrote: post #21

Earlier quoted context omitted.

Although higher humidity should make it feel warmer given the same ambient temperature. So if you're increasing the temperature mildly using this method AND increasing humidity, it may compound one another positively. Although, it is a minor efficiency gain either way.

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.

Re: Re-using the heat in bathwater in Britain

#138

Post by jtc331 »

cannam wrote: post #39
Someone1234 wrote: post #21

Earlier quoted context omitted.

Although higher humidity should make it feel warmer given the same ambient temperature. So if you're increasing the temperature mildly using this method AND increasing humidity, it may compound one another positively. Although, it is a minor efficiency gain either way.

I thought high humidity made it feel colder, when the temperature was relatively low? Hot damp air feels hotter than hot dry air, but I've had the idea that cold damp air feels colder than cold dry air. Is that a misconception?

I think “dry” and “damp” are two extremes. I feel warmer in 45% rH at 67°F in winter than at 30% rH same temperature, but the air doesn’t feel damp (OTOH 60% would start to approach feeling damp).

That being said, I think at normal conditioned air temperature ranges more humidity virtually always feels warmer. I’m not exactly sure where the cutoff is, but I’d guess below 60°F might be a decent guess?

Re: Re-using the heat in bathwater in Britain

#140

Post by dijital »

cannam wrote: post #39
Someone1234 wrote: post #21

Earlier quoted context omitted.

Although higher humidity should make it feel warmer given the same ambient temperature. So if you're increasing the temperature mildly using this method AND increasing humidity, it may compound one another positively. Although, it is a minor efficiency gain either way.

I thought high humidity made it feel colder, when the temperature was relatively low? Hot damp air feels hotter than hot dry air, but I've had the idea that cold damp air feels colder than cold dry air. Is that a misconception?

I think you're right and actually the extra moisture in the air would also mean that raising the temperature of the house requires more energy input since the specific heat capacity of water is higher than air.
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