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check valves

Discussion in 'Plumbing and Central Heating' started by Leadhillite, 27 Apr 2011.

  1. Leadhillite

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    Hi!

    A simple question here, which you guys will know the answer to straight off and only an amateur like me would ask!!

    I'm looking to use flexible pipes to take the supplies to my washing machine, (as there will be no service void behind the cabinets), but the catalogues say I need to use a check valve with them.

    I've googgled check valves and looked through this site, so know what a check valve does, but why do I need one if I use flexible pipes instead of copper pipe? (Feeling nervous now as I've used flexible pipes before, but not fitted check valves! :oops: )

    Any other advice will be very much appreciated.

    Thanks in anticipation.
     
  2. PRS1

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    Most domestic washers have an air gap inbuilt into them.
    This is to prevent any water within the washer (during use) being able to backflow down the pipes supplying it.
    These machines that have this inbuilt are usually marked WRAS approved!
    Some models dont ie;older Meile ones,and these need the check valves fitting,to comply with current water regs.
    Hope this helps.
     
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  3. Whitespirit66

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    Do you mean Speedfit/Hep20 plastic pipe, not the flexible hoses that connect to the machine.

    If its plastic pipe, you don't need check valves. Just make sure you put the correct inserts in the end of the pipe before inserting into fittings.

    I always like to fit wash. machine valves with check valves anyway, in case of back flow from the machine contaminating the cold water supply.

    http://www.screwfix.com/p/15mm-x-washing-machine-valve-with-check-valve/27660
     
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  4. plumber1722

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    hello

    i would say if in doubt fit a double check valve on the copper before the washing machine valve anyway i personally wouldnt trust a push fit so go for a compression fitting one

    hope this helps
     
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  5. Leadhillite

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    Thanks to everyone!!

    http://www.screwfix.com/p/wras-hose-15mm-x-15mm-x-1000mm-x-10mm/90671

    It WAS going to be that type of flexible braided pipe I was going to use, (but bought from TS not screwfix). On the TS site it said to use a check valve with these pipes, but I didnt understand why that was necessary.

    Sometimes asking a question out loud, or clicking the "post" button helps the more obvious answer to come into your head.....

    I realise now, that by far the simplest way to deal with the lack of space is to buy the 2.5m washing machine hose, which can simply lay on the floor under the cabinets and I will take it up through the floor of the cabinet to the water supply under the sink. DUH!!

    I've used these flexible braided pipes before, but never put a check valve in tho.

    I'm doing my neighbours kitchen for her as a favour, and she is buying a new Bosch washing machine, so following on from your advice(s), is it "better safe than sorry" to fit a Washing machine valve with a check valve in it, or, is it a case of overkill?? (Now I only ask, as some of the other posts I read suggest that a check valve can slow down the supply to the machine.)

    I always use compression fittings cos I just canny understand how push-fit stuff holds!!!

    Thanks again....

    A look at my handywork........

    http://www.homesaleonline.co.uk/property.php?propertyid=194
     
  6. Whitespirit66

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    The majority of people don't bother, but it doesn't hurt to put one on.

    However, as it's a brand new Bosch appliance, there's a good chance that it will be OK without.

    Up to you really.
     
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