Showers Pressure - Dual Shower heads

Discussion in 'Plumbers' Talk' started by peter hope, Aug 22, 2016.

  1. peter hope

    peter hope New Member

    Hi all,

    I’m a DIY’er and certainly not a plumber but I am a ‘give it a go’ kind of person with the fall back of getting a pro to fix any of my problems :)

    I have a nine year old house that has an unvented / mains pressure system.

    I am re-designing my main bathroom, which currently has a bath, shower, sink and toilet. If I run the shower (which is the furthest from the tank, if that is important?) and run a tap on the sink or bath (hot or cold) then the pressure drops in the shower.

    The redesign is to install a level access shower in the same location for my disabled son. The level access part I am good with and confident with the mechanism of waterproofing. The problem I have is that I want to install a rainfall from the ceiling with a completely separate handheld and I would like to run them together without any effect on the pressure. Any ideas?

    Thanks in advance.
  2. The main benefit of an unvented/pressurised system like yours is that you can run a couple of taps simultaneously.

    I think it's pretty obvious, tho', that there will be a drop in flow if two outlets fed by the same pipe (almost certainly 15mm) are opened at the same time. The question is, how much does the pressure drop? And is it normal and acceptable?

    As with opening a tap at the same time as your current shower, I think you can expect a 'drop' in flow from the rainhead when the handset is also used. But again, how bad will this be - how much is acceptable.

    I think what I would do is to contact the manufacturer of the unvented system (is the tank built in to the boiler like a Potterton or is the pressurised cylinder separate?) and ask them what flow rate you can expect x metres from the tank and fed by a 15mm pipe (if that is what you have). Then compare that with the pressure and flow requirements of your proposed shower.

    If you find that the system should - easily - supply your requirements, then it might come down to an issue like your cylinder isn't being pressurised properly - I understand they use an internal or external expansion vessel?

    Anyhoo, if you post the details of your system on here (the boiler and cylinder and proposed shower) and also contact the system's manufacturer, then between us we can hopefully come up with some answers :)
  3. peter hope

    peter hope New Member

    Thanks Devil, Appreciated.

    just to anwers a d=few of the questions that i can now.

    1. pressure - the pressure drops by at least half to the point where the current shower is almost useless
    2. Boiler is downstair, HW tank seperate with 2 pressure vessels (red/white).
    3. i think that this may have gotton gradually worse over this last year as i don't recall it being that noticable but also that said, thsi bathroom has only just been more frequently used in the last 3 years with the addition of children as this is the family bathroom. i mainly use the ensuit.
    Pipes - from what i can see (under bath and sink) 15mm plastic.

  4. Pressure dropping by half - that's clearly not right. (I'm not personally familiar with these unvented systems - other than my sis has one in her home - but understand the whole 'point' of them is good flow...)

    2 pressure vessels - is one larger than t'other? I'm wondering if one is to pressure the boiler/rads/system side, and the other is for the hot tank.

    Any visible pressure gauges, and what do they read? I think one (for the tank) should be around 3 bar and if the other is for the boiler system this should be less - anywhere from 1 to 2 bar.

    Do these needles fluctuate when you run a tap?

    My gut feeling is that there's an issue with your system - possibly an expansion vessel needing recharging - so once that's sorted you'll have all the shower power you could want... :)

    If the EV is shot, they are cheap to replace. (Should really be done by an accredited 'unvented' cove, tho', to be sure to be sure).

    Make of boiler? Make and size of hot tank?

    Pros will be along soon and will advise properly, I'm sure.
  5. KIAB

    KIAB Super Member

    Unvented cylinder, peep has to be unvented qualified'? to work on it, they need to be by law.
    Deleted member 33931 likes this.
  6. Fair do's. But had my sis's system needed a new EV, I guess I'd have done it myself... :oops:
  7. peter hope

    peter hope New Member

    Yep, i'm aware that work on boiler stuff needs to be G3(?) qual'd but i thought that i would be able to do the pipe work in the bathroom myself??

    2 pressure vessel, one for the CH and one for the HW. only have gauge on the CH side which is absolutly fine. looking about on the net and i am also leaning towards a pressure issue in the expansion tank for the HW. I have decided to get plumber in this afternoon to service it both boiler and HW system (think it is over due anyway:D) and also ask afew question about the showers whilst they are getting on. :p

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