additional pressure on unvented system

Discussion in 'Plumbers' Talk' started by TH4, Sep 7, 2014.

  1. TH4

    TH4 New Member

    Hi,

    I appreciate there are several threads on this topic but I have been unable to find a straightforward answer to a question I have:

    I have an unvented system (megaflow cylinder on ground floor) which does a decent job of providing all taps in house with pressure that is at or very close to the mains pressure of 2.5 bar. However, I am having a new ensuite built and would like more pressure in this one shower. I understand I can't have a pump pulling directly from the megaflo but is it possible to have an additional tank (break tank / accumulator) fitted in the loft to be used just for the shower and have a 4 bar pump pulling the water from that to the shower? Seems logical to me but just not sure how it will work with hot water.

    A secondary question that is less important is that while the megaflow is good at providing an equal 2/2.5 bar around the house, pressure is effected if more than one tap is open (i.e. can't use both bathrooms at once or flush a toilet when showering). Is that normal?

    Thanks in advance for bearing with my ignorence!
     
  2. plumberboy

    plumberboy Well-Known Member

    You would be better off aiming the accumulator at the whole house not just one bathroom,if sized correctly this will make a massive difference all round.;)
     
  3. tonyJ

    tonyJ New Member

    Hope you mean the WC doesn't refill if you are showering - otherwise you really do have an odd system.
    If the cold and the hot taps are both showing loss of pressure then its the supply to both that is restricted.
    Might be small pipes, might be poor mains pressure - or a part closed valve. Better to find the problem and correct that than fit additional bits that might (possibly) work for a few minutes.
     
  4. plumberboy

    plumberboy Well-Known Member

    Well there you go you have the answer TH4.:rolleyes:
     
  5. TH4

    TH4 New Member

    Thanks both. Mains pressure not fantastic in the area so i don't think increasing pipe size will help too much which is why I am thinking of the additional holding tank. My thinking is if that can fill up at 2 bar then i can pull from that at my hearts content. Piece i dont get is how do I keep water warm or do i need to get an additional heating element for the holding tank?

    Thanks for the pointer plumberboy, i'll enquire down that route - don't know any megaflow qualified tradesman in the Roydon (CM19) area that could do a professional assesment do you?!
     
  6. tonyJ

    tonyJ New Member

    2 bar is enough - but only if the pipes can carry the flow you need without significant pressure loss. Draw a schematic - get it checked !
    Additional elements in holding tanks starts to ring legionella alarm bells. Only a proper mains pressure HWS tank is set up to do that safely - DIY is not a good idea unless you truly understand what you are up to.

    You haven't commented on the incoming main. If your house is old enough for lead get rid of it and you will;-
    • a save yourself future failure (It's well past crystalline by now)
    • b stop poisoning your family and friends
    • c probably remove what ever is restricting your flow

    Up to the boundary will be done by the local utility company for free
     
  7. plumberboy

    plumberboy Well-Known Member

    As I said before just add an accumulator to the system this will give you the flow you desire, it's an easy job for any good plumber depending on where you site it.
    Any plumber with a unvented certificate can work on a megaflow so no problems there.;)
     
    TH4 likes this.
  8. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    Unvented have pressure reducing valves for safety, you don't have a pressure problem you gave a flow rate issue with supply fluctuations, an accumulator will give 90l/min from your current 25, the system needs to be surveyed & modified, there could is normally a few install faults & yes we can attend if required
     
  9. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

  10. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    2 x accumulators for 9 x bathrooms, 5 x outside taps, 3 x sinks, 2 x w/m, 1 x d/w & twin fridges dispenser, works as planned
     
  11. TH4

    TH4 New Member

    Looks great and would very much appreciate you coming round to provide assesment but I'm in Essex (CM19 5DD) and you look like you are in Hampshire?
     
  12. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    We can do Essex if you like
     
  13. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    Hi TH4
    On request, we are happy to conduct an on site survey,
    We will forward the installation & modification requirements to you after our visit.
    We produce an accurate description of proposed system improvements.
    Or if you just want some further guidance we are happy to help
     

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