Water hammer from unvented cylinder

[Taconite5]

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.

Yeah those ball ones - got any recommendations for a bigger one? All the ones I see online look like EV ones you'd use for an UV cylinder

 

[Johntheo5]

Zilmet make 2L ones but they are quite expensive, maybe because they are stainless and can withstand 15bar pressure?

 

[dilalio]

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

That's fine.

 

[dilalio]

What isolator do you have on the mains cold to the UV?

Photo.

 

[Taconite5]

What isolator do you have on the mains cold to the UV?

Photo.

It's a gate valve.


BC is balanced cold back down toward rest of house taps

 

[Taconite5]

Zilmet make 2L ones but they are quite expensive, maybe because they are stainless and can withstand 15bar pressure?

Yeah just had a look - be good to see if that would cure the problem before I commit to buying one! I'm surprised even the little one didn't quieten it even a bit!

 

[Johntheo5]

You said in your other thread that the mains pressure spikes from its normal 4.5bar to 8.0bar during the water hammer, you also say that the shock seems to be close to or at the UVC PRV, if so, I would install a 2L shock arrester close to the PRV end or maybe even better, T off from the balanced cold further along before it tees off to any of the users, set it to 3.0bar.

 

[Taconite5]

You said in your other thread that the mains pressure spikes from its normal 4.5bar to 8.0bar during the water hammer, you also say that the shock seems to be close to or at the UVC PRV, if so, I would install a 2L shock arrester close to the PRV end or maybe even better, T off from the balanced cold further along before it tees off to any of the users, set it to 3.0bar.

Yeah just thought fitting a pressure reducing valve at the mains after the meter would help or at least lessen the noise! I don’t get the spikes anymore but still hammers.

Just can’t get why it’s bad so and doesn’t happen when it’s settled for a bit and only when the hot is flushed through

 

[Johntheo5]

Hope your cylinder coil isn't like one of these .....

 

[Taconite5]

Hope your cylinder coil isn't like one of these .....

How come???

 

[Johntheo5]

Those corrugated coils can trap air in the corrugations but I suppose shouldn't cause water hammer.

 

[Justin Passing]

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?

The big one, if it's on the HW side.

 

[Taconite5]

The big one, if it's on the HW side.

Sure can.

Can you explain why the EV on the HW side would affect the cold taps if there’s a check valve in the ICG? Just trying to learn!

 

[dilalio]

How old is the installation?
Looks quite old from the photos supplied! Hate gate valves.

 

[Taconite5]

How old is the installation?
Looks quite old from the photos supplied! Hate gate valves.

3 years. New build is all I’ll say!!