Unvented HW Cylinder - Tundish leaking - safety question

[oldskoo1]

Evening

Tundish is leaking on a MegaFlo UnVented tank. I have attempted to repressurise to no avail.

Having tested the water dripping down, it is cool to the touch. Can I assume it is not an immediate safety concern?
Is it right to assume the PRV is calibrated to 7bar / 90c and if the expansion was critical it would open with extremely hot water?

Either was I will get it fixed but the advice on the above would reassure me that it isn't going to at worse explode!! Until I get someone here.

I presume it's a case of replacing the PRV. The tundish is covered in limescale deposits, so I assume it is debris causing a seal failure.

 

[Madrab]

Nope - an expansion issue usually presents itself as cold/cool water as it's the Pressure Relief Valve (PRV) on the combi valve (cold inlet) that's opening. When it's hot water presenting @ the tundish then it's more likely to be the Temperature/Pressure Relief Valve (TPRV) opening, releasing hot water from a 1/3rd of the way down the cylinder. The PRV reacts to excessive pressure only - the TPRV reacts to either excessive pressure or excessive temperature

Obviously neither is desirable and both need corrected quickly but if I was to say which I thought was a 'lesser safety concern' then it would be the PRV opening because of an expansion issue.

No - a lot of the time it isn't the PRV at fault, excessive expansion pressure has caused the PRV to lift. It's that excessive expansion that needs to be addressed first then if the PRV continues to pass then may the valve need looked at.

All of this is moot though - it needs a qualified engineer in to service the cylinder and check, test and replace it's safety features, An unvented cylinder is a regulated piece of equipment and is not DIY'able.