Water hammer from unvented cylinder

[Taconite5]

Wondering if anyone might be able to spread some knowledge on what I might do next as this water hammer is doing my head in!

The hammering noise occurs in the region near to the multibloc on my unvented cylinder. It only seems to happen after using any hot tap for a bit (which doesn't have a hammer) then switching to cold. It then makes a banging noise/thumping noise when the cold tap is turned off and on. If I leave the taps for a bit and don't use them the noise will settle when using the cold tap. But return again when I use the hot tap first then switch to the cold taps again.

I've tried so far -

Getting the multibloc replaced (this is set at 3 bar)
Replacing the expansion vessel and checking it's charged (3 bar)
Fitting a pressure reducing valve to the mains (it was previously spiking to over 7 bar but typically was sitting around 4 bar) - now down at 3bar
Putting a water hammer arrestor before the multibloc (set at 3.5 bar)
Even tried replacing the cartridges in all the taps!

Any other ideas?

I've had a few G3 people look at it and they are stumped! Problem is I can't keep bringing them out just to have a look - so any ideas and where I can direct them would be helpful!

 

[dilalio]

What make and model uv?
What make and model control group?
Is the hot and cold balanced and both taken off of the control group?
Is the EV taken from the correct port of the control group?
Have you tried depleting the cylinder of hot water and seeing if problem occurs with a cold tank?
Some photos would be useful.

 

[Johntheo5]

There's a lot of info on @Taconite5 s "Water Hammer" thread.

 

[Justin Passing]

Drop the pressure in the PV. If it's at 3bar, and the water offered to it is also 3 bar, it won't do anything, no flow of water.
If it's at say 2 bar, the water will flow in, compress the gas until it's at 3 bar as well, and give a means to absorb spikes or fill drops of pressure, like a shock absorber.
What you're doing is like running a car on springs which are not compressed at all in normal running.

 

[Taconite5]

Drop the pressure in the PV. If it's at 3bar, and the water offered to it is also 3 bar, it won't do anything, no flow of water.
If it's at say 2 bar, the water will flow in, compress the gas until it's at 3 bar as well, and give a means to absorb spikes or fill drops of pressure, like a shock absorber.
What you're doing is like running a car on springs which are not compressed at all in normal running.

Yeah can do.

Which PV? The small hammer arrestor one on the inlet/mains on the multibloc or the big one on the cylinder side?

 

[Taconite5]

Yeah it goes for a bit thinking I’ve solved it. Then back to square one!!

 

[Johntheo5]

Once again, what make/model of UVC

 

[Taconite5]

Once again, what make/model of UVC

What make and model uv?
What make and model control group?
Is the hot and cold balanced and both taken off of the control group?
Is the EV taken from the correct port of the control group?
Have you tried depleting the cylinder of hot water and seeing if problem occurs with a cold tank?
Some photos would be useful.

It's a ThermaQ Evocyl 180 L TTPI-00180-L2C

The control group according the cylinder manual is a TZG-3.0-00.75L Joule 22mm Multibloc Cash Inlet Control Valve 3/6 Bar - but it has Caleffi on the body of it.

When you say balanced what do you mean? The ICG is set at 3bar. Both are taken off it

The EV is taken off the outlet via a T after the PRV before it goes into the cylinder, rather than from the dedicated port. I asked Joule about this and they said it's an acceptable location?

I haven't tried emptying it - to do this - how do I use the taps if the stopcock to the ICG inlet is closed?

Also attached an audio of me opening and closing the tap twice, recording taken from next to the ICG.

Download Cylinder.m4a | LimeWire

Download Cylinder.m4a on LimeWire

limewire.com

 

[dilalio]

Where does the hidden connection from the control group go? Can't see from the photos! The pipe off the back of it... Does that go to the EV or balanced cold? Where is the EV connected in?

 

[Taconite5]

Duplicate post - see below

 

[Taconite5]

Where does the hidden connection from the control group go? Can't see from the photos! The pipe off the back of it... Does that go to the EV or balanced cold? Where is the EV connected in?

It's blanked off.

There's a T below going to the cylinder inlet that feeds the EV.

Balanced cold is the top right one

 

[Taconite5]

Layout of the pipes - the only thing I haven't included is I added a pressure reducing valve set at 3bar were the blue star is. And a hammer arrestor on a T before the ICG

Region around the ICG is where the banging is coming from

 

[Johntheo5]

This is where the EV is normally taken off but the T take off should be fine IMO.

 

[Taconite5]

This is where the EV is normally taken off but the T take off should be fine IMO.

Yeah I asked Joule (the cylinder provider with ICG etc) about this as it's not according to the installation manual. But they said it's acceptable. Just makes it hard work when something breaks eh!

 

[Johntheo5]

Layout of the pipes - the only thing I haven't included is I added a pressure reducing valve set at 3bar were the blue star is. And a hammer arrestor on a T before the ICG

Region around the ICG is where the banging is coming from

Is that arrestor taken off the T before the ICG one of those tiny ones?, if so a 2/5L maybe set to 2bar might be better if you have the room to install it.