Water Hammer - Banging sound from taps when Shutting the taps off?

Niv

I am experiencing some water hammer in a similar sounding circumstance to you OP. I haven't don't it yet, but as a quick / cheap fix (hopefully) I will be installing a couple of water hammer arrestors as below as these require little plumbing / disruption.
https://www.screwfix.com/p/sioux-chief-dw660-h-water-hammer-arrestor-bsp-connection/9813r
If that doesn't work I may have to rip out a significant amount of boxing to see if the pipes need better fixings to hold it to the wall.

mazibee

@Niv Thanks for your reply.

I have used one on the cold water supply under the sink,

After that the kitchen mixer cold is not hammering , but toilet aFter filling in the tank and  bath mixer still hammering on both hot and cold even after installation of the hammer arrestor  under the kitchen sink

https://www.screwfix.com/p/reflex-expansion-vessel-shock-arrestor-0-16ltr/8199V

Is there any difference in working

https://www.screwfix.com/p/reflex-expansion-vessel-shock-arrestor-0-16ltr/8199V

and

https://www.screwfix.com/p/sioux-chief-dw660-h-water-hammer-arrestor-bsp-connection/9813r

mazibee

Jeepers_Creepers said:

mazibee said:

Thanks @Jeepers_Creepers

I checked the water pressure by opening the stop valve fully, I attached the pressure gauge on the line under the sink

Working Pressure was 2 bar with cold water tap opened fully and the standing pressure was 4.5 bar when tap closed but the gauge needle jumped t and fluctuated before setting to 2 bar when I turned the tap off.

I also checked the flow of the water and it was 18litres per minute on the Cold tap and 10 liters per min on the hop water tap

Hammering sound is not coming when I am turning the cold water mixer tap quickly ,I think  due to the water hammer arrestor fitted on the cold line.

Hissing sound is coming form the mixer tap when the both cold / hot is opened slightly,

Also I tried to check the pressure in the Hammer arrestor vessel, on the label it says Factory setting is 3.5 bar when I checked it was 1.08 bar , it tried filling with the pump and still its gone to 1.4 bar ,

Any idea on how to fill this small 0.16 l Reflex Hammer water arrestor properly to 3.5 bars.

Strangely,  I also found that there are two stop valves under the sink, one just above the other with a small space in between them.

Any further suggestions keeping in view of the above findings.

Thanks in advance

4.5bar static is high. You will almost certainly notice a significant improvement if you fit a PRV and set it to, say, 3.5bar.

This shock arrestor has a Schrader valve on it then? When you were pumping it up, were you doing this against the pressure of the water on the other side? Do you know what make it is? Try and find the proper instructions 'cos I don't know.

Any chance of a photo of these two stop valves?!

The shock is caused by the change in pressure. Pipes have some flex and 'give' in them, very much so if they are plastic. When you shut off the water, the pressure jumps upwards, makes the pipes expand a tiny amount for a moment before they settle back to their original size = pressure swings and 'shock'.

Fit another shock arrestor on the hot side too I guess?!

Please find attached photos of stop valve, hammer arrestor under the sink, and the boiler.

Niv

mazibee said:

@Niv Thanks for your reply.

I have used one on the cold water supply under the sink,

After that the kitchen mixer cold is not hammering , but toilet aFter filling in the tank and  bath mixer still hammering on both hot and cold even after installation of the hammer arrestor  under the kitchen sink

https://www.screwfix.com/p/reflex-expansion-vessel-shock-arrestor-0-16ltr/8199V

Is there any difference in working

https://www.screwfix.com/p/reflex-expansion-vessel-shock-arrestor-0-16ltr/8199V

and

https://www.screwfix.com/p/sioux-chief-dw660-h-water-hammer-arrestor-bsp-connection/9813r

I am not an expert but I think that principally both work in the same way. The one you have installed has a bigger capacity so theoretically 'could' work better. However I also presume that location of the arrestor in the line will also have an effect. So if the arrestor were near the area of noise perhaps it would work better, I honestly don't know. 
The reason i am going for the ones I linked as a first option was simply due to their ease of installation (undo hose to washing machine, screw in, reattach hose).

Jeepers_Creepers

Yup - two stopcocks! Tobesure tobesure.

You have plenty of room there for a PRV.

Do you know where your external stopcock is? I suspect the lower stopcock is faulty so someone added another instead of shutting off the water outside and just replacing it.

If you - or a plumber - shuts off the mains water outside the house, you should be able to replace these two stopcocks with a full-bore lever valve in the lower position (that'll make shutting off the water in future much easier and quicker) and a PRV above it.

When it comes to recharging an arrestor, I understand (like a boiler EV) that you have to release the water pressure from the other side first. Do this by shutting off the mains stopcock (whichever one that works!) and opening a cold tap to release the pressure in the pipework (eg the cold kitchen tap). Now recharge the arrestor to 3.5bar, which should be doable. Bear in mind that it's a very small capacity, so won't take much pumping to do this, but it is a highish pressure, so will need a good squeeze.

And is that another arrestor above the boiler?! I can't ID it - it looks like a magnetic filter, but surely cannot be as it doesn't appear to be connected like one, so I guess it's another shock arrestor! Again, does it have a make on it?

As I said before, 4.5bar is too high. It won't cause issues in many homes, but it will in plenty others - as you have found. I'm not a plumber, but it strikes me as being silly to try and arrest all these shocks when the cause - too high a pressure - remains.

Access to your pipes is easy, so this will be the simplest of jobs for a plumber.

I think what I would do is to explain the situation, see what they say, and then try and come to an agreement that you'd like to try the PRV on its own first to see if that's enough, but being prepared to add another arrestor too, as close to the cause as possible (eg near the bathroom).

Jeepers_Creepers

Niv said:

mazibee said:

@Niv Thanks for your reply.

I have used one on the cold water supply under the sink,

After that the kitchen mixer cold is not hammering , but toilet aFter filling in the tank and  bath mixer still hammering on both hot and cold even after installation of the hammer arrestor  under the kitchen sink

https://www.screwfix.com/p/reflex-expansion-vessel-shock-arrestor-0-16ltr/8199V

Is there any difference in working

https://www.screwfix.com/p/reflex-expansion-vessel-shock-arrestor-0-16ltr/8199V

and

https://www.screwfix.com/p/sioux-chief-dw660-h-water-hammer-arrestor-bsp-connection/9813r

I am not an expert but I think that principally both work in the same way. The one you have installed has a bigger capacity so theoretically 'could' work better. However I also presume that location of the arrestor in the line will also have an effect. So if the arrestor were near the area of noise perhaps it would work better, I honestly don't know. 
The reason i am going for the ones I linked as a first option was simply due to their ease of installation (undo hose to washing machine, screw in, reattach hose).

As you realise, the 3/4" BSP arrestor model is designed for simple fitting in-line with a washing machine fill hose. So I wouldn't use it anywhere else as it'll simply be more tricky to install.

Have you tried the 'pressure' and 'flow' tests like Mazibee? I mean, is the cause a pressure that's simply too high? If it is, it's placing unnecessary stress on your system.

mazibee

@Jeepers_Creepers

Extremely  thankful for your time to reply

On top of the boiler,Sentinel filter is fitted,

I am not happy with that filter and plan to replace it with MagnaClean system, as it cannot be accessed so easily and cleaning the filer is a difficult task for me due to the awkward location.

In September 2020, first boiler service was carried out, when I queried the person regarding  whether that filter on the top of the boiler has been cleaned and he replied no need and will check in the service next year. Does it seems OK.

I also asked him to quote me on replacing that Sentinel filter  with Magnaclean system and he replied that there is no room for MagnaClena to be fitted . I was shocked again?

Please can you or someone who deals with these sort of issues/ problems on daily basis tell me, if I plan to install a PRV, it should be installed before of after the stop valve?

Thanks again for all your help and time

Jeepers_Creepers

PRV - fitted after the mains stopcock (don't forget to have your daft double-SC issue sorted as well. I really do recommend full-bore lever valves as they make life a lot easier and don't tend to seize or fail.)

Sadly, looks like 15mm pipework before and after your stopcock? if so: https://www.screwfix.com/p/pegler-ball-valve-blue-15mm/11085 or the 22mm equivalent if that's what the pipes are (much better).

Ah, so that is a filter - looks like the Sentinel model has fancy features and has a single connection to the pipe instead of the more common top-and-bottom.

https://www.youtube.com/watch?v=W-nGDv6cl14

Blimey, you ain't going to be cleaning that any time soon...

How to sort? That return pipe coming through the ceiling needs to be diverted away to a position where a filter can be installed, before then resuming its path back to the boiler. Very limited where it is, tho'; no space above the boiler, there's a wall unit to the right, and to take it in front might then make removing the front panel of the boiler very awkward.

In most boilers, that return pipe connects at the bottom of the boiler - I wonder if that's the case with yours? (Make and model?) If so, the obvious place would be to extend that return pipe beyond the bottom of the boiler, fit a filter there and then have the pipe loop back up to the boiler. An alternative would be to take the pipe inside that wall unit!

mazibee

The boiler installed is Worcestor Greenstar Style Gr8700iw 30 Cb Ng

Niv

Jeepers_Creepers said:

Niv said:

mazibee said:

@Niv Thanks for your reply.

I have used one on the cold water supply under the sink,

After that the kitchen mixer cold is not hammering , but toilet aFter filling in the tank and  bath mixer still hammering on both hot and cold even after installation of the hammer arrestor  under the kitchen sink

https://www.screwfix.com/p/reflex-expansion-vessel-shock-arrestor-0-16ltr/8199V

Is there any difference in working

https://www.screwfix.com/p/reflex-expansion-vessel-shock-arrestor-0-16ltr/8199V

and

https://www.screwfix.com/p/sioux-chief-dw660-h-water-hammer-arrestor-bsp-connection/9813r

I am not an expert but I think that principally both work in the same way. The one you have installed has a bigger capacity so theoretically 'could' work better. However I also presume that location of the arrestor in the line will also have an effect. So if the arrestor were near the area of noise perhaps it would work better, I honestly don't know. 
The reason i am going for the ones I linked as a first option was simply due to their ease of installation (undo hose to washing machine, screw in, reattach hose).

As you realise, the 3/4" BSP arrestor model is designed for simple fitting in-line with a washing machine fill hose. So I wouldn't use it anywhere else as it'll simply be more tricky to install.

Have you tried the 'pressure' and 'flow' tests like Mazibee? I mean, is the cause a pressure that's simply too high? If it is, it's placing unnecessary stress on your system.

One for the dishwasher one for the washing machine is the plan with those particular ones. 
Yea I have and I know my water pressure is high so longer term will need a regulator I think.