shower pump on unvented system

Discussion in 'Plumbers' Talk' started by andrewtheface, Mar 15, 2009.

  1. andrewtheface

    andrewtheface New Member

    is this ok or a no no
     
  2. HOTDOG ø

    HOTDOG ø Active Member

    No permitted and surely not even needed?
     
  3. Water Systems

    Water Systems New Member

    Sounds as if an accumulator is needed. What is the static pressure in bar? What is the flowrate at the kitchen tap in litres/minute?
     
  4. Onetap

    Onetap Member

    Not permitted, but generally not required.


    An unvented water system uses the water company's pump to deliver the pressure and flow rate. If either is inadequate it is likely that the service pipe from the mains to your house is too small, or the pressure &/or flowrate were inadequate for an unvented system in the first place. The installer should have checked both before installing it.

    I think you need to ask approval before connecting most pumps direct to the mains (more than 12 l/min?). You'd usually need a break tank before the pump to avoid the possibility of the pump sucking a negative pressure in the mains and syphoning the contents of someone's pond or bath into the water supply system.
     
  5. Water Systems

    Water Systems New Member

  6. tackleburger

    tackleburger New Member

    Grundfoss do one as well.
     
  7. Onetap

    Onetap Member

    Look at one of these:
    http://www.challiswatercontrols.co.uk/products/heatedt
    owelrails/TWINSTREAM.htm

    A pump and accumulator on the mains.


    Yes, Drivel, a pump and accumulator on the mains. With the flow rate restricted to 12l/min to comply with the Water regulations, just as I'd said.

    Two points regarding your post.

    12 l/min is bog all flow rate and the Users will get right fed up when they've exhausted the water stored in the expensive accumulator by the expensive, but pathetic pump. They'd be better off with a break tank in the loft (if they have a loft and the mains pressure can get to it) and a water booster pump.

    Secondly, neither pump nor accumulator should be required. Either the main servce pipe is undersized or an unvented system shouldn't have been installed. Like I said above.
     
  8. Water Systems

    Water Systems New Member

    The Mainsboost is "primarily" for mains that are under 1.5 bar. Otherwise a normal accumulator will do and give flow and 1.5 bar min' pressure - the static pressure of the mains.

    You size the accumulator to suit. The pump can raise the pressure to 4 bar if you want. It just does not draw from the mains more than 12 litres/min.

    The Mainsboost can also be used to boost the mains to higher pressures.

    A break tank takes up space, and requires a pump running on all draw-offs.

    The Mainsboost can be made by anyone. A flow regulator set to 12 l/min and a appropriate pump to get to the required bar, high limit pressure switch, accumulator and pressure relief valve.
     
  9. Water Systems

    Water Systems New Member

    Grundfoss do one as well.

    It is not an accumulator and boost the mains - so I believe.
     
  10. doing a bit

    doing a bit New Member

    whats your cold mains pressure like ?? if thats good then a check on the unvented controls is required, BUT only done by a suitably qualified person, could be a faulty prv on the system
     

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