I'm attempting to build a recirculating shower. I envision it like this: a bather will take a soapy, cleaning shower of 2-10 minutes to clean themselves, then take a potentially longer hydrotherapy shower with clean recirculating water.

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After the cleaning shower the bather will remotely (via cable) close a drain valve. When enough water backs up to the top of the drain, water sensors 1 & 2 will detect that and activate the pump. The pump will push water through the heater and up to the shower head. If the temperature sensor detects that the water is not warm enough it will activate the heater.

When the bather hears the pump turn on he will turn off the water from the shower mixer, the shower's original water source.

When the bather is done with the hydrotherapy he will open the valve. When water sensor 2 detects no water it will shut off the pump and heater, which is piggybacked on the pump circuit.

I've listed most components on an Amazon list (https://www.amazon.com/gp/registry/wishlist/2ZIFY1GU45F52). It shows two alternatives for the pump and strainer: a separate pump and strainer, and one that is combined. The list excludes the 3/4" or 1/2" brass tee and possible check valves that connect the recirculating system to the original shower pipe.

I'd like to hear your feedback on the feasibility of this and if you have suggestions for better components, configuration, etc.

Hi Roel

I'm off to work and will revisit this later tonight, but first quick thoughts are that you would DEFINITELY need check valves, and most likely, if you want this approved by a plumbing inspector in any way, you might want to install a second shower valve with separate control so that dirty water can never cross/enter into the potable water system. Here, even if the shower valve has check valves, dirty water and bacteria ener the clean water system... that is something that is definitely frowned on!

Next, the aluminum heater you posted is thermostatically controlled from 135F to 175F so you would need to add a Honeywell (or similar) type of mixing valve to reduce water to 115F MAX to the shower.

Ill pop back later. Wait until Hkstroud sees this, I'm sure he'll have some helpful thoughts!

Mark

Check with Kohler. They used to make such unit, very similar to what you are describing. It was a pre-fab tub with enclosure ( one piece , including ceiling) with jets built into the walls. They operated independently from shower and tub spout and were activated by electronic touch pad.

Milo

Mark, I was planning on putting check valves in but, as you mention, bacteria may crawl around the valve when the pressure is removed. Is there no valve setup that will prevent bacteria from flowing back? I also plan on putting in vents, but I forgot to draw them.

Milo, yes, I saw that Kohler had a system called the BodySpa. I believe it was in the $12,000 range. :/ It also used probably 30 gallons of water at least. My system will use probably less than 5 gallons.

A Watts 9D back flow preventer should work (see image)... Accepted to keep dirty boiler water and associated bacteria from "back flowing" into clean (potable) water of the house.

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You would still need a separate shower valve or a Watts 9D on both the hot and the cold water lines from what I can tell.

In terms of vents, you mean vents for the drain line?

Darn, those backflow preventers are expensive!

You just won't be able to adjust recirculation flow.

Yes, vents for the drain lines. On second thought I shouldn't have a vent on the recirculating circuit, to limit contamination.

Ptrap needs to be directly under the shower... otherwise it is an Strap (illegal in all states of USA). Vent should be within 5 feet of the Ptrap and don't worry about contamination here... what drain lines are for!

Are you thinking about installing the second shower valve? I would do that... will not need the backflow preventers in that case.

Here's a blowup of the P trap. The vent is less than 5 feet to the right. Yes, there is no contamination here as long as I don't have a vent on the recirculation circuit that is connected to the other vents.
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Concerning the shower valve I was considering many options initially, but it seems to me that even if I install a second shower valve there is a chance of contamination unless the bather ensures that the first shower valve is closed before opening the second shower valve (and of course vice versa). A back flow preventer both ensures that no contamination occurs and allows for a cleaner look and simpler operation. Did I understand you correctly?

If you completely separate the valve, I.e. install a second valve and shower head the clean system will not be contaminated, and back flow preventers will not be needed.

Ah, yes, I knew that was what you meant. I don't know why I didn't address that configuration. Yes, that would be an easy solution. My setup without the recirc was going to be a wall mounted shower head and an overhead rain head. I'd like to be able to use both of them without the recirc (in case the recirc fails :/ ), so I already have two heads and want to limit it to those two. But you are right, I will consider limiting the rain shower to the recirc. Thanks!

Ptrfeeds to be directly under the shower... otherwise it is an Strap (illegal in all states of USA). Vent should be within 5 feet of the Ptrap and don't worry about contamination here... what drain lines are for!

Are you thinking about installing the second shower valve? I would do that... will not need the backflow preventers in that case.

Actually, s traps are not illegal in some applications; most toilets require an s trap in order to promote siphoning of solid waste...

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Could I use the LF7R, LF7R Lead Free* Brass Dual Check Valves, Dual Checks / Dual Checks with Atmospheric Vent, Backflow Prevention - Watts (http://www.watts.com/pages/_products_details.asp?pid=7452), instead of the 9D? I found one for $10 on eBay.
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Hi Roel. I don't see why not... if anything, it is a better valve than the Watts 9D. Keep me posted on final design so I can double check safety devices like temp. and pressure relief valve at the water heater, etc...