Water Hammer - could this be an 'ok' solution?

Discussion in 'Plumbers' Talk' started by r18rws, Jun 2, 2021.

  1. r18rws

    r18rws Member

    I have water hammer and cant get rid. I have added some small hammer arresters on the quick close devices, so toilets, and washing machine. The taps are not slow close versions in the bathrooms. Kitchen still a fast close but is on the point of entry so not impacting the longer pipe runs. Already have a PRV on the mains inlet and set to around 3.5bar, though even when lower the hammer was still there.

    Currently using combination of
    Sioux Chief DW660-H Water Hammer Arrestor ¾" BSP Connection | Hammer Arresters | Screwfix.com
    on washing machine and
    15MM Anti Water Hammer 0.16 Litre Shock Arrestor Easy Fit Mini Expansion Vessel | eBay
    (similar to something which screwfix used to sell) on the toilet inlets.

    The white rechargeable one is 0.16 litre it says and was from Screwfix though no longer for sale. Worked fine for maybe 6 months at a time before needing a recharge but this time they are not charging, maybe the valves have gone bad, or my pump! They are 5 years old now and a couple are looking a bit rusty and worse for wear. The fixed unit on the washing machine worked immediately but after 3 months seems to be knocking a it again.

    I want to try to resolve it more reliably. Though I cannot get to the pipes in the ceilings that bang to clip them.

    Would adding something like this to the mains inlet provide a better solution. More robust with larger air gap, this is not too large to fit but will still wipe what is left of my under kitchen space so only going to attempt it if it is worth it. Flomasta Potable Expansion Vessel 2Ltr | Expansion Vessels | Screwfix.com
    Fitting it would just be and equal tee, 15mm/15mm/half" BSP female like this Compression Adapting Tee 15mm x 15mm x ½" | Pipe Fittings | Screwfix.com being used to tap into the main feed in at the appropriate place with the 1/2" BSP female for vessel to screw in to? Just for location purposes and ease, would it be acceptable to take the mains inlet and use flexi pipe to go to the tee so the expansion vessel can be located in a slightly better position, perhaps 600mm length. The existing piping is in a difficult position and this would be helpful. Full bore piping to avoid pressure and flow issues etc.


    Or any other great suggestions on a solution. Considering ripping the floors up or ceiling down isn't one of them.

    Thanks in advance
    Rich
     
  2. Jimbo

    Jimbo Screwfix Select

    A larger vessel with the pressure when empty set to a little under the 3.5 bar regulated pressure should certainly allow the water somewhere to go
     
    r18rws likes this.
  3. Severntrent

    Severntrent Screwfix Select

    You could try turningdown the main entry stop tap to the lowest level that you are willing to accept on your incoming flow but that size of vessel should sort it.
     
  4. r18rws

    r18rws Member

    Well I have added the expansion tank to the main inlet and its not made any difference at all. Pressure needs to be slightly below the normal operating right?

    I installed on the right side of the PRV, so its after that in the run into the house. Presume that's the right place, not before it.

    Other than altering the pressure I am lost now... The mains inlet is set at 3.5bar on the PRV. Only other thing is to perhaps switch the vessel on each of the toilets and the washing machine which seem to be the culprits, and perhaps use the Peglar option in Screwfix now Pegler PEG62 Water Hammer Arrestor Male Threaded Connection | Hammer Arresters | Screwfix.com, no air chamber to recharge and looks to be more mechanical. that's 4 of them I need though so all beginning to add up. Or some way of making the toilet fill close off less abruptly. They are the button and tall pole fills rather than ball cock.
    Fluidmaster Bottom-Entry Pro Bottom Entry Fill Valve ½" | Fill & Flush Valves | Screwfix.com
     
  5. Jimbo

    Jimbo Screwfix Select

    The pressure of the vessel when empty needs to be below the supply, so that the water can expand in to it. You could start at say 2.5 bar. Air can just be let out the valve until the pressure is reached.
     
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  6. r18rws

    r18rws Member

    No matter the vessel pressure the issue wasnt resolved. Next thing to try is the peglar arrestor and see if they are any good, one on the worst toilet then if works I will replace the rest.

    Relaly thought this woudl have done the trick but sadly not
     
  7. r18rws

    r18rws Member

    UPDATE - the peglar thing works ok. Will stick with them for now. Look very robust, hopefully they are reliable.
     
    Severntrent likes this.

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