This is knocking and water is leaking from somewhere you can't see what's causing it?

[endecotp]

Hi It's a Tesy bilight 80litre tank, the importers told me the expansion vessel should be fitted on the hot side despite the manufacturers instructions saying the opposite.

Do you have the manufacturer’s instructions?

I spoke to the manufacturers which are a Polish company when I got it who told me that they don't bother with expansion vessels over there.

If they also don’t fit a non-return valve then it can expand back up the incoming supply pipe. But UK regs require a non-return valve to prevent contamination of the supply, which limits the available pipe to expand into. So an expansion vessel is needed.

 

[endecotp]

The MI also states a pressure reducing valve

It sounds like you’ve found the instructions madrab - can you post a link?

(I can decipher the Polish if necessary….)

 

[polesapart]

This is almost certainly a generic euro unvented product imported without UK type approval/certification. Cheap for a reason.

With the correct safety inlet group and appropriate expansion vessel (and safety discharge pipework) hard-piped in it probably could be made to work safely, if illegally.

Finding a competant G3 qualified bod prepared to work on it might be difficult.

IMO

 

[Gary111]

Heres the manual

https://www.manuals.co.uk/tesy/bilight-80-h/manual

 

[Gary111]

From looking at that it says if the incoming pressure exceeds 6 bar a pressure reducing valve should be fitted.​

Then something about not using the pressure relief valve supplied.

 

[Gary111]

 

[Gary111]

Having looked through that it seems to me that the problem is that the pressure relief valve should be 6 bar instead of the 3 bar one that's fitted.
I've messaged the plumber about that.

 

[endecotp]

Thanks for the link to the manual.

It is designed to rely on its built-in pressure relief valve passing when it heats up. This isn’t allowed in the UK - hence the various bits saying “If the local regulations (norms) require the usage of another protection valve or mechanism (in accordance with EN 1487 or EN 1489), then it must be bought additionally.” One such mechanism they’re referring to is the expansion vessel. Another would be an over-temperature relief valve.

They want it to be installed in a room with a waterproof floor with a drain, i.e. a wet room. Failing that, I think “protective tub” should be “tundish” but I’ll need to check that.

Do we actually have anyone reading this who is G3-certified?

 

[dilalio]

Do we actually have anyone reading this who is G3-certified?

Yes

 

[endecotp]

They want it to be installed in a room with a waterproof floor with a drain, i.e. a wet room. Failing that, I think “protective tub” should be “tundish” but I’ll need to check that.

No, apparently the Polish version advises installing it over a bath or sink to catch the outfall from the PRV if you don’t have a wet-room floor.

 

[endecotp]

Yes

And what do you think? In particular, what do you think about having the expansion vessel on the output rather than the input, as advised (apparently) by the importer?

 

[Madrab]

Do we actually have anyone reading this who is G3-certified?

yes 2

 

[Madrab]

TBH The expansion vessel can be on either side - it is preferable to have it on the cold side as that tends to keep the vessel cool rather than the hot side but both will absorb the expansion from the vessel.

Who installed this, was it notified and is there a cert as there obviously is no benchmark? TBH there are a few issues around this piece of equipment. I still have an issue where there doesn't seem to be a TPRV fitted.

 

[Gary111]

Thanks is there a way of installing a TPRV on that?

 

[dilalio]

And what do you think? In particular, what do you think about having the expansion vessel on the output rather than the input, as advised (apparently) by the importer?

I think that, without any proper documentation to follow nor technical support for UK installation, I would swerve it.

It should not be available for sale here without such.

I found and downloaded the manual about a week ago and had a quick look, mainly for installation diagrams as I'm not into reading 3000, badly translated words. I was unable to read the diagrams as they were bitmaps and would not scale up. That's as far as I went.

We follow guidance that is the result of proper safety testing, at research facilities, we can't make up our own.

European UV use is very different to ours and is largely unregulated. That's fine, if something goes wrong then no one gets punished (except perhaps their conscience). Here it's different.

I have worked on, installed and repaired, many UV cylinders, both direct and indirect and the most important aspect for replacing any safety device(s) is to use those with the correct pressure release limits, as prescribed by the manufacturer.
There are many variations, I recently changed one that was 10bar.

We have no way of knowing what pressures can safely be withstood by the appliance.

As per @Madrab the absence of a tprv, when there was one previously, has me wondering if this is purely a cost saving measure by the manufacturer as no regulation to demand one?

Maybe it's because it's a direct cylinder and the internal electric heating elements have high-limit stats that would prevent such temperatures ever being reached!

We just don't know.