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Holy crap that re-circulation feature is luxurious! I'd love to have something like that! Whenever I take a hot shower I fantasize about putting in a liquid-t

Holy crap that re-circulation feature is luxurious! I'd love to have something like that! Whenever I take a hot shower I fantasize about putting in a liquid-to-liquid heat exchanger so the hot water can heat up the cold water and you can run the hot water at a much lower temperature. This application with the bath tub feels way more justified.

kalleboo 7d ago
And this is the builder-grade model we got from the house renovation company. There are higher grade ones with fancier stuff...
OhNoNotAgain_99 7d ago
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londons_explore 7d ago
Presumably you need a bath with extra plumbing? What happens when the heat exchanger gets clogged with soap and hair?
bluGill 7d ago
Many people have thought about the drain heat exchanger. However drains need to be way oversized for various reasons and so you can't get good contact with the water: it is mostly air in the drain pipes.
shellfishgene 7d ago
That does exist. Simple versions just have a large, deep drain with coils the cold water runs through. Fancier ones have a proper heat exchanger next to the shower (requires a pump) or in the basement. Water sanitation rules probably make it non trivial to get a design certified.
- gandreani 6d ago
  Is the deep drain to diminish the air pockets at the exchange surfaces?
  - shellfishgene 6d ago
    It's just so the cold water pipes sit in a pool of warm water. https://www.meanderhr.com/wp-content/uploads/2012/11/HXdrain-heat-recovery-shower-drain-heatexchanger.jpg https://www.meanderhr.com/wp-content/uploads/2012/11/HXdrain... This is even simpler: https://warmduscher.de/produkt/warmduscher-original/ https://warmduscher.de/produkt/warmduscher-original/
quickthrowman 6d ago
Here you go: https://www.homedepot.com/p/Hydro-Systems-Fusion-Low-Voltage-Circulation-Heater-for-Tub-Only-29-102/303819884 https://www.homedepot.com/p/Hydro-Systems-Fusion-Low-Voltage... Drain heat exchangers are really expensive, this 3” by 48” copper one costs over $1000: https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Water-Heat-Recovery-Unit-R3-48/203456041 https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Wa...

kalleboo 7d ago

And this is the builder-grade model we got from the house renovation company. There are higher grade ones with fancier stuff...

OhNoNotAgain_99 7d ago

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londons_explore 7d ago

Presumably you need a bath with extra plumbing? What happens when the heat exchanger gets clogged with soap and hair?

bluGill 7d ago

Many people have thought about the drain heat exchanger. However drains need to be way oversized for various reasons and so you can't get good contact with the water: it is mostly air in the drain pipes.

shellfishgene 7d ago

That does exist. Simple versions just have a large, deep drain with coils the cold water runs through. Fancier ones have a proper heat exchanger next to the shower (requires a pump) or in the basement. Water sanitation rules probably make it non trivial to get a design certified.

gandreani 6d ago
Is the deep drain to diminish the air pockets at the exchange surfaces?
- shellfishgene 6d ago
  It's just so the cold water pipes sit in a pool of warm water. https://www.meanderhr.com/wp-content/uploads/2012/11/HXdrain-heat-recovery-shower-drain-heatexchanger.jpg https://www.meanderhr.com/wp-content/uploads/2012/11/HXdrain... This is even simpler: https://warmduscher.de/produkt/warmduscher-original/ https://warmduscher.de/produkt/warmduscher-original/

quickthrowman 6d ago

Here you go: https://www.homedepot.com/p/Hydro-Systems-Fusion-Low-Voltage-Circulation-Heater-for-Tub-Only-29-102/303819884 https://www.homedepot.com/p/Hydro-Systems-Fusion-Low-Voltage... Drain heat exchangers are really expensive, this 3” by 48” copper one costs over $1000: https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Water-Heat-Recovery-Unit-R3-48/203456041 https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Wa...