Monday, November 30, 2009

DIY heat exchanger for your shower

Update December 2011: You may now buy the new affordable DWHR unit for stand alone shower cabinets at the HeatSnagger Shop  (Norwegian link: Varmegjenvinner for dusj )

Update April 2011: Arthur and I have joined forces and are now working on a commercial, low cost DWHR unit based on this blog post. You may follow our progress at Meander Heat Recovery
Nov 2009:
I got an E-mail from Arthur Kimmels. He has come up with a DIY concept for a small shower heat exchanger, a drain water heat recovery (DWHR) unit. I really like the simplicity of this design. His mail speaks well for itself, so here it is:

Hei Svein,

With interest I read your blog about miljødusj I had been walking around with a similar idea of building a heat exchanger for the shower (before I read about miljodusj, but inspired by some products on the Dutch market), and after some months of thinking and building I installed it today. Attached you will find some pictures of the unit. It is built of wood, coated with fiber glass and polyester. It measures 85x32x12cm. The water channels have an inclination of approximately 1cm/m. The heat exchanger is built of ca. 4m copper, 12mm diameter and soldered together. It works as 'counterflow'. A disadvantage of this setup is the pressure drop/flow reduction due to the long PEX/copper/PEX length (ca. 8m), but I measured this to be within acceptable limits for my setup. The measured temperature increase at a flowrate of ca. 10liter/min was 23.3(out) -8.8 (in) or 14.5degC. Total material cost was ca. NOK 1500, including PEX tubes to and from the unit. (The thermometer in the picture measures at the in and outlet, I removed the 'indoor' sensor from the housing and soldered it to some wire.)
Feel free to add to your 'blog'.
Kind regards, Arthur Kimmels
Summary in Norwegian: Arthur har laget en enkel varmeveksler for dusj. Avløpsvannet fra dusjen brukes til å forvarme kaldtvannet som kommer inn i dusjen. Temperatur økningen på kaldtvannet er målt til 14.5 C. Det medfører at man bruker mindre varmtvann og dermed sparer energi. Spillvarme gjenvinning i praksis.


Mr Muscle said...

I guess the problem with all ideas of grey water heat recovery is cleaning, so please post some pics after a couple of months.

Arthur said...


Thank you for your feedback.
I will post my experiences with the heat recovery unit in due time, including pictures.

However, I am not too concerned about fouling or clogging up, because it is very easy to take the unit apart, remove it from its place and clean the 'channels' and the copper pipe.

Tor said...

Cool blog and very nice picture on the header!

(PS: You've spelled beautiful wrong in the "about me" section. Not that it's a big deal, just thought I should be a spelling-nazi and point it out ;)

Svein* said...

Thanx. Yes, we want the planet to be beautiful. I fixed th spelling mistake.

Heat Exchanger said...

it is really a nice blog to read i like it very much.

Micheal Hussey said...

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Heat Exchanger said...

Watch How a heat exchanger works

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