Chris NottEM Tuning
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  1. #1
    Yeee-haw
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    Question for a plumber - pressure reducing valve

    Morning all,

    In my 2001 built house I've got a 2.1 bar PRV on the supply. This seems a bit underpowered, especially with the garden hose. I'm guessing it's required, as it's a newish house and I can't see the company that built it stretching to any extra expense. I want to change it out, but what is a safe pressure for the house piping to take?

    Cheers,

    Mike

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  3. #2
    treblesykes's Avatar
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    Can you not take water for your outside tap before it passes thru the valve? Its likely that the valve constricts the flow as well as the pressure.

  4. #3
    Yeee-haw
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    I thought of that, but it likely involves more intrusive work that is just as cost, if not more so, and also needs more time. I can't access the piping for the outside tap easily. I can get at this PRV easily.

  5. #4
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    My combi boiler is kn@ckered i have to keep addind more pressure to it every week or so but my plumber mate said it should be at about 1.3 bar. i keep putting it up to 1.6 without any problems.
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  6. #5
    james0808's Avatar
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    Just take the prv out.Your house pipes will take the mains pressure.

  7. #6
    Yeee-haw
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    Quote Originally Posted by james0808 View Post
    Just take the prv out.Your house pipes will take the mains pressure.
    I'm thinking about it - it just seems a bit of a high risk strategy. I'm just a bit confused as to why it is in there.

  8. #7
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    Quote Originally Posted by Geordie Mike View Post
    I'm thinking about it - it just seems a bit of a high risk strategy. I'm just a bit confused as to why it is in there.
    Its there to stop the cheap plastic push fittings used in the most modern of houses instead good old soldered joints from going pop and causing floods!

    Putting my serious hat on for a second, its only going to be safe to remove the prv if the mains pressure is sufficiently low enough not to cause a strain on the houses plumbing, especially joints. Another thing to consider is the max feed pressure of your boiler. Also, what sort of shower(s) do you have in the house? If your running a hot water tank system then if you up the cold water pressure you overpower the hot water system meaning your showers are cold, not good!

    Best bet is have is looked at by a proffesional plumber to guage what your true mains pressure is, and what effects you'd have by removing the valve, or fitting a higher flow valve. Word to the wise, plumbing is tricky stuff so avoid DIY fiddling if you've no idea what your doing!
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  9. #8
    Yeee-haw
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    I think what I'll do is check out my neighbours houses and see whether they have one. I'm at the end of a street with only fields beyond me to the North and all previous development to the south, so I'd be surprised if I was where the water comes in. There is a pumping station about 1.5 miles from me too.

    Thanks for all the advice offered though people.

    Mike

  10. #9
    james0808's Avatar
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    Quote Originally Posted by Nickynibbles View Post
    Its there to stop the cheap plastic push fittings used in the most modern of houses instead good old soldered joints from going pop and causing floods!
    Speedfit connectors are rated about 10 bar at 25 degree celcius and drops with heat to around 4 bar.You will have nowhere near 10 bar water pressure in your house,lucky to get 3.

    Quote Originally Posted by Nickynibbles View Post
    Another thing to consider is the max feed pressure of your boiler.
    You can put the prv just before the combi boiler,if thats what you have.If you have hot water storage,the boiler is fed from its own tank so doesnt use mains pressure.

    Quote Originally Posted by Nickynibbles View Post

    Also, what sort of shower(s) do you have in the house? If your running a hot water tank system then if you up the cold water pressure you overpower the hot water system meaning your showers are cold, not good!
    Really does depend what type of mixers you are using.You can get bi-mixer showers which mix at the outlet so hot and cold can be mixed independently and you can have any temp you need.
    If you are using a normal electric shower with only cold feed it will work just the same.

  11. #10
    TDI-line's Avatar
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    GM,

    do you have a combination boiler, or a conventional boiler with an unvented hot water cylinder, like a megaflo or mainsflow cylinder.

    If you have the latter, then the PRV is used to reduce the pressure for these stored hot water vessels, otherwise, in time they can leak or discharge with too much pressure.

    If you have a conventional cylinder with tanks in the loft feeding it, then this would not apply.

    And as James said, all existing pipework should be fine for upto 10 bar.

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  12. #11
    Yeee-haw
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    Conventional cylinder, no tanks in the loft. I've decided to leave well alone until I have a plumber in for something else

  13. #12
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    Do you have two tanks above the hot water cylinder?

  14. #13
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    There is a small what looks like an accumulator (from memory)

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    Caesium's Avatar
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    That's a mains fed hot water storage cylinder and the thing on top is an expansion vessel. 15mm Copper pipe has a bursting pressure of 2256 Bar so your mains will not pose a problem. The water restriction valve is probably more down to the amount that can be supplied to your street.
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    Caesium's Avatar
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    Quote Originally Posted by TDI-line View Post
    If you have the latter, then the PRV is used to reduce the pressure for these stored hot water vessels, otherwise, in time they can leak or discharge with too much pressure.

    Not always, these units are rated up to 3 bar and are normally supplied with a pressure reducing valve to be fitted on the incoming pipework to the cylinder, not the whole house. They have a pressure release valve which can in time start leaking into the tundish but not normally from overpressure, normally from being scaled up or perishing.
    Chris

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  18. #17
    james0808's Avatar
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    The prv could also be an oversight from when the boiler was installed.The installer could of missed it out and then realised his mistake and did the old bodge it in the easist place.There are alot of cowboys around.

    Did you check to see if your neighbours had this prv also?

  19. #18
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    Quote Originally Posted by A4Quattro View Post
    Not always, these units are rated up to 3 bar and are normally supplied with a pressure reducing valve to be fitted on the incoming pipework to the cylinder, not the whole house.
    This is very true and can reduce from around 12 bar to 3 bar.

  20. #19
    Caesium's Avatar
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    Quote Originally Posted by james0808 View Post
    The prv could also be an oversight from when the boiler was installed.The installer could of missed it out and then realised his mistake and did the old bodge it in the easist place.There are alot of cowboys around.

    Did you check to see if your neighbours had this prv also?
    this sounds the most likely story
    Chris

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  21. #20
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    What is the problem do you have , as you mention a PRV whats up with it ? is your garden hose water flow to weak or too strong ? are you sure it`s a PRV .
    as said most mains throughout the country are lucky to get 3bar , the water board has to guarantee at least .5 bar .

    cheers
    chris

  22. #21
    PaulMc
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    I have a Megaflow, but also a PRV, so that the pressure is reduced otherwise the water softener couldnt cope.

  23. #22
    Caesium's Avatar
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    **** the plumbing, love the avatar PaulMc..!
    Chris

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