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Thread: Flow/pressure problems-Multi tank passive

  1. #1

    Default Flow/pressure problems-Multi tank passive

    Hi all, firstly I am a master electrician not a plumber. Electrical theory I am good with but have absolutely no training or technical knowledge of plumbing systems.
    I designed and built a three tank solar collector which I installed in series with my existing electric heater. My theory is that when solar falls short electrical would act as back-up.

    I cut the 3/4" cold supply to the electric and sent it to the solar. The solar I piped in 1/2" cpvc and returned the hot side to the electric cold supply inlet.

    I installed two isolation valves and a bypass valve so I could isolate the solar in the event of problems and go to bypass and essentially be back where I was with the exception of a reduction from 3/4" pvc to 1/2" cpvc at the electric cold supply inlet.

    I piped the solar in 1/2" to slow the flow so as to collect more heat and so expected some flow reduction but upon my first shower I was in for a real depressing surprise. There was barely enough (pressure/flow? ) to climb from the spout to the shower head.

    In bypass there is a noticable drop in (pressure/flow?) but is livable.

    I isolated both supply and return pipes to / from the solar, good flow in both.
    There is good flow through the solar.

    So my initial questions are:
    A) Do 90's (slow/restrict) (flow/pressure) ?
    B) What is the effect of line length?

    Any other constructive criticism would be greatly appreciated.

    PS: I am in Florida and the collector tanks are (2) 40 gal. well pump tanks and (1) 40 gal electric heater tank stripped out of the cover and insulation.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    Every change of direction and increased length will slow the flow. Under static conditions, the pressure will be the same, but swapping to 1/2" probably wasn't a great idea.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3

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    Thanks, I did several searches on this site and found what I believe is the answer to my problem (or at least one answer) and that is the sizing and length. Rather than using 1/2" cpvc I should have upsized to 1" and all the changes in direction within the solar added to the increased length would slow the flow.

    That brings about another question. Since all the inlets and outlets on the tanks used are 3/4" threaded,how do I connect 1" cpvc to them? Or does the upsize up to the inlet/outlet suffice?

    Or should I use 3/4" galvanized since I am able to cut and thread? My pocket is really shallow so copper is out of the question.

  4. #4
    Illinois Licensed Plumber SewerRatz's Avatar
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    They make fitting adaptors to go from " to 1" piping.

  5. #5

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    Sorry,I didn't express myself correctly, I didn't mean the physical connection from 1" to 3/4", rather, does going from 1" to 3/4" at the threaded hub do any good or is upsizing to 1" a waste of material. ie: Since the hub is 3/4" then anything larger is useless?

  6. #6
    Illinois Licensed Plumber SewerRatz's Avatar
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    Quote Originally Posted by natec904 View Post
    Sorry,I didn't express myself correctly, I didn't mean the physical connection from 1" to 3/4", rather, does going from 1" to 3/4" at the threaded hub do any good or is upsizing to 1" a waste of material. ie: Since the hub is 3/4" then anything larger is useless?
    Ah sorry. Up-sizing the pipe will increase the volume of water that will flow through the 1" pipe. When you decrease back to " you will decrease the volume but increase pressure. Also with 1" pipe in your solar collectors you will reduce the pressure drop in the developed length and all the turns. Where as if you keep it all " you will get more pressure loss through the panels.

  7. #7

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    Thanks SewerRatz, I'll upsize the CPVC to 1" and let ya know how it works out. I needed some small pipe for my rabbit watering system so all is not wasted.

    natec904

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