Re-using the heat in bathwater in Britain

Re:Re-using the heat in bathwater in Britain by godelski on Sunday October 30, 2022 @10:35PM (#33401436)

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.

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Re:Re-using the heat in bathwater in Britain by Retric on Sunday October 30, 2022 @11:14PM (#33401667)

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 temperature and will warm or cool the soil surrounding pipes at any reasonable depth if you are using water regularly.

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Re:Re-using the heat in bathwater in Britain by robertlagrant on Monday October 31, 2022 @03:48AM (#33403046)

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?

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Re:Re-using the heat in bathwater in Britain by Retric on Monday October 31, 2022 @07:06AM (#33404197)

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.

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Re:Re-using the heat in bathwater in Britain by SECProto on Monday October 31, 2022 @02:53PM (#33410808)

People don't experience it because the water heater output is a consistent temperature. There's nothing to experience with increased consumption of electric/gas/heating oil, especially when those concurrently increase for home heating

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Re:Re-using the heat in bathwater in Britain by Retric on Monday October 31, 2022 @07:10PM (#33414646)

That assumes the water going into the water heater changes temperatures which as I just said isn’t always the case. Some people take “cold” showers year round and the tap is very consistent.

Trivially people in the tropics don’t have a winter, but well water can similarly have very consistent temperatures independent of seasons.

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Re:Re-using the heat in bathwater in Britain by SECProto on Sunday October 30, 2022 @11:58PM (#33401886)

> I'm not convinced of SEC's 2-3x estimated increase

It's a simple calculation, but very location specific. In my particular case, if the water heater is set to 50C, and tap water is 22C in Summer, it has to impart a ΔT of 28C. If your tap water is 4C in winter, the ΔT is 46C. Not quite double, but close to it. If your water heater is in a poorly conditioned space, then it would lose considerably more heat to the surrounding space when outside temperatures are -15C than when outside temps are 35C. All told, hot water energy usage for my particular situation is between 2x and 3x. Other situations would vary, but still significant.

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