Very Loud banging

[grobbarg]

Hope someone can help.

I recently had a new bathroom suite and non-vented indirect cylinder (Ariston WRc-NSF and all related hardware) installed.

Initially there were no problems, but now - occasionally when a hot water tap is turned full on, or when the washing machine hot water valve opens there is a very loud banging noise coming from where the cylinder is installed. I can't determine 'exactly' where the noise is coming from, as by the time I've run through to the room where the cylinder is installed, the noise has subsided.

The noise starts off as a rapid succesion of banging which then slows down. If the tap is turned off after the banging starts, the noise will carry on for a few seconds. Could this be a hardware problem, or trapped air?
Thanks in advance for any advice.

G

 

[Gasguru]

Turn off water supply to cylinder, turn on hot tap. When water stops flowing check the air pressure in the expansion vessel near the cylinder. The correct pressure should be written on the vessel.

 

[grobbarg]

Cheers Gasguru,

As a newbie to non-vented systems (but OK with a spanner) how would I check the expansion vessel's pressure? there's a threaded connection on the top of the vessel, is that a charging point and how do check the pressure without losing the charge? The label has been scraped right where the charge value is - it looks like 6.5 bar (8 bar max).
It's a 'Varem'. Incidentally, the vessel has been mounted horizontally, would that have any effect?

G

 

[Gasguru]

Remove the valve cap (same as a car type valve)

Use a normal tyre pressure gauge and check pressure is about 3.5 Bar. Water to cylinder must be turned off and hot taps open.

 

[grobbarg]

OK Gasguru,

Checked vessel pressure with supply off and taps open - it was just under 3 Bar.
Used foot pump to pressurise to 3.5. Unfortunately as the symptoms are intermittent I can't immediately check if this works or not. Perhaps I should have also mentioned the noise seems to mostly occur in the morning or when returning from work in the evening - i.e after a period of no useage.
What are the implications of too low or too high expansion vessel air pressure? anything else that should be checked?

Ta v. much.

G

 

[tomtom82]

Can i just say im not a plumber and im only throwing a possibility out there of what i have experienced and therefore is probably not the right answer. But check you dont have debris from the installation of your new bathroom stuck in a valve such as ur toilet.

When i had my new toilet installed which was a cheap B&Q gravity flush thing, my boiler started to vibrate vigerously and bang very very loudly which sounded like someone was drilling next door. I called the plumber who raced round as he thought a fan had fallen off or something. He isolated the toilet and the vibration stopped, and opened the filling mechanism and bits of grit fell out. Turns out this was causing the valve to 'bounce' as he put it and cause the noise/banging. Hope it all gets fixed ok!

 

[grobbarg]

Well, the noise is definitely coming from the cylinder area, when any hot water tap is suddenly switched on so it's gotta be something there - I think. Perhaps I do need to remove some tank related hardware and check for debris ?

 

[grobbarg]

Just cleaned out a load of white greasy crud from around the pressure reducing valve filter - could this be the problem?

 

[grobbarg]

In answer to my own question - no, this does not cure the problem, in fact it seems worse - please, does anybody have any more ideas? it's driving me nuts....

 

[gigz]

i've just been called out for the same problem (intermittent, mainly first thing in the morning) never happened when i was there but the lady had video'd it. Canged the temp/pressure relief valve, now sorted. Not a DIY job though.

 

[doitall]

i've just been called out for the same problem (intermittent, mainly first thing in the morning) never happened when i was there but the lady had video'd it. Canged the temp/pressure relief valve, now sorted. Not a DIY job though.

What the hell has the temp/pressure relief valve got to do with it

Was the plumber that installed it qualified for un-vented cylinders, did he give you a balanced cold.

Whats the mains pressure, I suspect you need a shock arrester fitting on the mains supply

 

[gigz]

Sorry meant combi valve, my mistake

 

[grobbarg]

Thanks for the replies,

The plumber is qualified and had fitted the same system in my parents house with no problems, but that was a totally new system/pipework etc direct from the mains. Unfortunately he's now gone on an extended vacation down under.

There is no balanced cold, all the cold taps seem to be using the original mains supply. Not sure what the mains pressure is though - I'll need to get a gauge.

All the parts came as a kit with the Ariston cylinder, the combi valve etc are all 'Reliance water controls'. Is it possible the pressure reducing valve could be faulty already? Also, there is some minor water hammer on switching the taps off, so would it be worth fitting a shock arrester in any case?

 

[doitall]

Yes it would be worth fitting one by the incoming main stopcock.

If you have quarter turn taps they can cause problems with the higher pressure.

 

[HannahK]

I am having the same problem, exactly, with another varem. Please please let me know if and how you eventually resolved this. Thank you, H