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

Jeepers_Creepers

Niv said:

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.

How high is high?

Jeepers_Creepers

mazibee said:

The boiler installed is Worcestor Greenstar Style Gr8700iw 30 Cb Ng

Nothing unusual in the way that model is piped up from what I can see. The flow and return pipes can therefore be brought to the boiler from below as well as from above (which yours seems to be). It won't be pretty, but an obvious solution would be to extend the return pipe down to just below the boiler, fit the filter there, and then loop back up to the boiler. The filter would sit to the left of that double-socket under your boiler.

The only other solution is as I said before - give up part of that wall unit for it!

Hang on - where does the pipe go when it passes through the ceiling? Is the hot cylinder up there? Any chance you can fit it there?  (Photo of cylinder cupboard please...)

mazibee

@Jeepers_Creepers

Thanks again.

Sorry for any misconfusion, its a Combi Boiler.

Before we moved in the house , previous owners used to have a Worcestor System Boiler, but we replaced it with the Combi and removed the Tank from the loft  cylinder from the Airing cupboard in one of the bedrooms,

So currently we have a Combi and dont have any cylinder and tank.

Jeepers_Creepers

Ah, my first surf for that make came up with 'system' boiler, but I now see it's a combi. Where does that return pipe go once it's through the ceiling? It doesn't appear in that bedroom cupboard, does it?

If not, I guess it's back to either the side of the boiler, or below it.

mazibee

Hi @Jeepers_Creepers Sorrry for bothering you again.

I cant locate where the pipes are are going as on top there are bedrooms which are all carpeted and underneath they plywood is fitted on the floor boards.

Where the pipes are going in the ceiling , on top is my sons room and banging is most in that room.

Few more questions coming in  my mind, if you or someone else can please can suggest.

-- Any advantage of installing the PRV , instead the flow can be reduced by the stop valve, or if there any advantage that I open the stop valves fully and control the pressure by PRV.

-- Is there a way to replace the quarter turn tap cartridges instead instead of replacing the whole kitchen mixer tap.

https://www.screwfix.com/p/cooke-lewis-58a-deck-mounted-dual-lever-bridge-mixer-kitchen-tap-chrome/7390T

--If the system already has X100,  can I add X200 to the system and leave it or the system need to be drained after adding X200 after certain time.

Jeepers_Creepers

mazibee said:

Hi @Jeepers_Creepers Sorrry for bothering you again.

I cant locate where the pipes are are going as on top there are bedrooms which are all carpeted and underneath they plywood is fitted on the floor boards.

Where the pipes are going in the ceiling , on top is my sons room and banging is most in that room.

Few more questions coming in  my mind, if you or someone else can please can suggest.

-- Any advantage of installing the PRV , instead the flow can be reduced by the stop valve, or if there any advantage that I open the stop valves fully and control the pressure by PRV.

-- Is there a way to replace the quarter turn tap cartridges instead instead of replacing the whole kitchen mixer tap.

https://www.screwfix.com/p/cooke-lewis-58a-deck-mounted-dual-lever-bridge-mixer-kitchen-tap-chrome/7390T

--If the system already has X100,  can I add X200 to the system and leave it or the system need to be drained after adding X200 after certain time.

If the pipes aren't anywhere obvious in that room - and where a filter could be fitted - then best to forget anywhere except the area immediately around the boiler.

There, your options would still appear to be to divert the pipe as it comes through the ceiling to a new position where the filter (either the existing or an alternative) is fitted; this would either be (as far as I can see) in front of the boiler or inside that wall unit.

Or, continue the return pipe as it comes down behind the boiler to the bottom - take it further down, fit the filter there, and then loop back up to the boiler. It won't be pretty there, but perhaps you could even take it to below that worktop (what is that?) so it's out of sight? There's already a copper pipe in that corner - two more won't hurt, and they can be boxed in afterwards. I'd personally go for this option if possible - get it under that unit.

That's one issue.

The other is the hammering. X200 is a scale-remover or something - ie it's designed to reduce boiler noise such as sizzling and kettling caused by a build-up of summat. You have 'hammer' - a totally different cause.

Do you know anything about electricity, other than it makes your lights go on and can kill? Do you understand voltage and current, for example? Cool. Well, V and C are the same as Pressure and Flow.

P&F are completely different to each other, but are connected. You can have HUGE flow with next to zero pressure, and HUGE pressure with next to zero flow. But, for the same supply, increasing one also increases the other.

Have you used a pressure washer? LOTS of water comes out the end, yeah? No. Less water comes out the end of your lance than would pour out the supplying garden hose. All the PW has done is boost the pressure a huge amount, whilst actually using less water that could be supplied to it via the garden hose.

What does this mean for your house? Well, the 'pressure' is provided by the water board, and yours is a bit high at 4.5bar, high enough to cause issues when you have loose pipes and stuff. You ideally want to reduce that to a gentler ~3.5bar. You also have a max flow that comes in, and you've measured that as being around 18lpm. That is good, but not exceptional. You don't want to reduce this at all.

What would happen if your partially closed off the mains stopcock? You would reduce the flow - not what you want. Would it also reduce the pressure? Well, yes and no, or should I say, no and yes. Your 'static' pressure would not drop an iota. If you are not running a tap, then the pressure on the mains side of your stopcock would be the same as the pipework in your house - 4.5bar. Nothing will have changed, 'cos the two sides are still connected via the (partially closed) SC and the pressure will equalise. Yes? Cool.

However, if you now open a tap, the pressure on the house side will drop alarmingly, to below the 2 bar 'dynamic' pressure you had before. This is because you have reduced the available flow, so your tap's supply will be reduced - ergo the pressure on the house side will plummet because the mains cannot keep it up (you've partially closed off the SC). You'll now have a deeply unpleasant situation where you've compromised your water flow from your taps, and reduced the pressure behind this flow, but as soon as you close off the tap, the pipework pressure will go right up to the original static 4.5bar. If you close off the SC enough, you'll notice a strange instant gush when you first open a tap ('cos the pipes are at the stored static 4.5bar) followed by a near-immediate huge drop in flow (as the stored pipe pressure is released and plummets because it can no longer be maintained by your half-closed SC). I'd call that the worst of both worlds...

So, what you actually want is the nice 18lpm flow to remain, but to be delivered by a reduced pressure of, say, 3.5bar.

And that's why you need a PRV :-)

Wake up. I said WAKE UP!