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Community and Q&A

3 Way Max flow valvue

peterb2000 | Posted in Mechanicals on

Hey all!
I’m currently the owner and builder of a fairly large single family home (4000 sq ft). I have done most of the plumbing and mechanicals myself with a lot of thanks to this community!

My current predicament is optimizing water flow through a 1″ hot water trunk line (that has a recirc loop/pump). We added a heat recovery pipe (“Power Pipe”) to capture energy on the drains. The predicament is the water line in the Power Pipe is done in 3/4″ and I’d like to not lose the potential max flow available that the reduction from  1″ to 3/4″ for the entire spiral of the pipe will cause. I’m trying to come up with a solution that would keep all the flow through the Power Pipe when the flow can be handled by the Power Pipe but if the demand is higher than that some water from the main cold line would bypass the Power Pipe to the hot water tank to allow for the max flow on the main hot water line.

I’m not sure if there is some kind of valve that would be pressure sensitive that could accomplish something like this or if anything like this is possible.

Thanks in advance!

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  1. DC_Contrarian | | #1

    Run the Power Pipe output into the cold water input of the showers only.

  2. Expert Member
    BILL WICHERS | | #2

    I like DC's idea: simple and effective!

    If for some reason that doesn't work, keep in mind that restriction to flow is based on diameter AND length of the pipe. You may well find you can connect your Power Pipe and not really notice any flow reduction. If that doesn't work out, you can plumb a 1/2" bypass in with some T fittings off the main line so that the 1/2" bypass is in parallel with the Power Pipe, and put a ball valve in the 1/2" bypass line. Measure the flow of the main pipe alone, then measure the flow coming out of the Power Pipe with the ball valve closed (which means water flows ONLY through the Power Pipe). Now gradually open that 1/2" ball valve while monitoring flow rate, and keep opening the ball valve until you see the flow rate get up to about what it was off the main line ahead of the Power Pipe. You've now adjusted things so that most of the flow goes through the Power Pipe, but the 1/2" bypass carries enough to make up for the pressure drop in the Power Pipe.

    My own preference would be to avoid a bypass loop here though, since it will lose some efficiency in terms of heat recovery. You need to balance your desire for high flow rates with your desire to recover as much heat as possible with the Power Pipe.


  3. peterb2000 | | #3

    Thanks for the thoughts! Unfortunately we are too far along in the build to go with DC's idea but that would have been the perfect solution so we will have to go with Bill's. Here's hoping the power pipe doesn't cause much of a flow restriction.

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