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Discuss Choice of Pressure reducing valve in the Plumbing Forum area at

  1. Koomber

    Koomber New Member

    Renovating bathroom just now and the wife wants mixer taps throughout. Normal single handle hobbj on the sink and a fancy traditional style beast on the bath.

    Hot water is supplied from unvented cylinder at 2 bar closed pressure, 1.5 bar ish when flowing full tilt. Cold is supplied from mains at about 4 bar closed in.

    I'll need to fit a pressure reducer on the cold side and I'm wondering if altecnic are any good as the y are significantly cheaper than Honeywell. I'm well aware of the adage you get what you pay for so illI pay for Honeywell if I have to, but I thought I'd at least check with the pros.

    I'd guess I'd need to set it for roughly the operating pressure of the hot water system rather than the closed in.

    Should I also fit a non return valve?
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    wheres the unvented cylinder in relation to the bathroom?
  3. king of pipes

    king of pipes Trusted Plumber GSR

    I would fit flow restrictors on the supplies to the taps or on the taps have a look on here . Cheers kop

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    • Agree Agree x 1
  4. Koomber

    Koomber New Member

    Unvented is next door to the bathroom. Maybe about 3m of pipe between the bath and the taps.

    KoP, I never thought of that! Bloody hellfire I'm a spoon. I've got a basin upstairs that spews water out the sink when the bairn opens the taps full tilt and it never occurred to me to fit them! A cracking point.

    Also, save money cut carbon have some really good prices for stuff.
    • Agree Agree x 1
  5. Best

    Best Trusted Plumber

    Why is there no balanced cold supply?
    There usually is a draw off connection at combination valve (but some are different). Need a G3 unvented plumber to do any work related to the unvented unit.
    All your taps should have had flow restricted by aerators in end of spout or flow regulators fitted in pipes to each tap. Madness to have full flow on every tap on high pressure plumbing
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    • Agree Agree x 1
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  6. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    my thought exactly
    • Like Like x 1
  7. Koomber

    Koomber New Member

    The bathroom is 'downstream' of the hot water cylinder, the previous taps were all separate taps and the previous owner who had it installed had the mains go to those taps I'm guessing since the feed from the mains was there and it was easyea than doubling back the cold from the tank to the taps.
    There is a balanced cold feed coming off the tank which goes to the upstairs bathroom.

    I never really gave it much thought about the flow restrictors to the taps. We just never opened them up enough to cause a problem. Feel like a bit of an idiot now.

    What qualifies as working on the cylinder to need a G3 certified plumber?
  8. Best

    Best Trusted Plumber

    Any work on the unvented cylinder or the controls (plumbing and electric) generally needs to be done by a G3 plumber. Also includes most of the pipework including the discharge pipework.
    So for example, a motorised valve supplied with unit is a safety component and you cannot touch that.
    Same with an immersion heater, or any thermostat.
    The pressure relief valves and combination (pressure reducing) valve also only a G3 plumber can work on.
    But nothing to stop you working on hot and cold pipes in rest of house
    • Winner Winner x 1
  9. Koomber

    Koomber New Member

    Cheers best. I've been going by the rule that if it's close to the hot tank than the gate valves, I ain't touching it so sounds like I should be okay. I saw that episode of mythbusters! Same with the boiler. Too much electric on that for my liking.

    So, I need flow reducers for the taps to get a sensible flow but will I also need pressure reducers as well since the bathroom has the cold off the mains?

    Taking the balanced cold back from the hot water tank to the bathroom would be a bit of a nightmare at this point.
  10. chris watkins

    chris watkins Plumber

    Or install new Pressure Reducing Valve, dial up type, set to just over 2.3 Bar on the incoming mains supply (ground floor).
    Flow restriction stops splashing & saves water but will not stop possible cross-flow or poor tap mixing due to differential pressures.
    Water Regulations require a check valve on both the hot & cold supply to any mixer tap or valve set because of the contamination risk.

    You are right Koomber you genially get what you pay for RWC PRV's are good or better still a fully qualified Plumber with their Water Reg's & Un-vented ticket.
    • Winner Winner x 1
  11. Koomber

    Koomber New Member

    Thanks for all the advice guys.
    • Like Like x 1
  12. Tim S

    Tim S Member

    Honeywell or Calleffi pro's are usually good..
  13. Rob Foster

    Rob Foster Top Contributor!!

    Honeywell are really the best and very expensive, I specify prvs for major manufacturing projects and that’s the choice I make they are probably £20+ to an end user. The Italian ones are cheaper and there are some that are £5.00 in my world Pay up and buy American Also read the spec and if you are using large vols of water I think they have to be horizontal can’t remember
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