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Discuss Instant hot water heater before or after pump? in the Bathrooms, Showers and Wetrooms area at UKPlumbersForums.co.uk.

  1. justin tuijl

    justin tuijl New Member

    Hi, I have a bespoke system in an old building I did myself. At the moment I have the pump before the instant hot water heater. I wondered if it would be better to put it after the pump? So it pumps cold into the heater, rather than pulls hot out of the heater. Thanks for any help.
     
  2. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    What sort of pump? Tank fed cold? Check that heater can deal with pumped
     
  3. chris watkins

    chris watkins Plumber

    In simple terms pumps work best pushing rather than pulling, why do you ask?
    Who designed your bespoke system Justin?

    PS. welcome to the forum.
     
  4. justin tuijl

    justin tuijl New Member

    Thanks for the welcome.

    The pump is a twin impeller shower pump and the hotwater heater a Thermomate ELEX12 Instant Water Heater 12kW Tankless fed from a cold tank. I made the system, I did it by guesswork, first go at it.
     
  5. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Sounds dangerous mate. Why not just install an electric shower
     
  6. justin tuijl

    justin tuijl New Member

    Unfortuntely I went one way with it. At the moment it works, just with the pump pulling through the water heater. I ended up with a non-power shower, kind of stuck with what I have now.
     
  7. chris watkins

    chris watkins Plumber

    Is the idea to improve the flow rate from the pumped hot?
     
  8. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Doesn’t mean it’s not dangerous. What flow and pressure can the heater deal with. If it’s tankless are you pumping mains??
     
  9. justin tuijl

    justin tuijl New Member

    Yes, that's right, the flow is a bit lacking. No mains. It's flitered rainwater.
     
  10. justin tuijl

    justin tuijl New Member

    I wish I knew the flow rate, I was puzzled over that.
     
  11. chris watkins

    chris watkins Plumber

    Unfortunately it is the 12kW heater that is the limiting factor here.
    Why do you think most properties store hot water in cylinders.
     
  12. justin tuijl

    justin tuijl New Member

    I have a cyclinder too, just not fitted it yet.
     
  13. justin tuijl

    justin tuijl New Member

    Ah, ok
     
  14. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Fit it
     
    • Agree Agree x 1
  15. chris watkins

    chris watkins Plumber

    You will be lucky to get 6LPM @ 30deg C rise in temperature out of it.
    I do hope you had someone who knows the wiring regs connect up the power to it, this is not a diy item.
     
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