If you can persuade the Client, I would get Gledhill out to view and comment on the installation / collapsed tank.
Whilst you don’t need to be G3 qualified to change washers et al on a pressurised system, you really do need to understand the principles of how the system operates and the importance of venting when draining it down.
Often these things are not clear cut.
Personally, I don’t think that the G3 course covers sufficient detail about the process and need to avoid the creation if a vacuum in an unvented cylinder. It is very easy to do this unintentionally when draining down an unvented system when the tank is at or near the highest point of the installation. Draining off bellow the tank with the cold water supply isolated has the potential to create a vaccum in the vessel. I suspect this is part of the problem here - or did you ensure that the tank could freely vent either from the prv or preferably by slackening the hot water draw off connection.
Think of the tank like a crisp packet - it takes a hard blow to burst it, but only a very gentle suck to collapse it.
Hi,
Thanks for the reply.
The first thing I did was to read the manual on draining down the system. Yes as you mentioned, negative pressure created in a cylinder can cause it to Implode, however on a call I made to Heatrea sadia technical support, I’d gone through the exact step by step process of drain down, changing taps and filling back up.
The technical guy responded by saying that there was no way of imploding the cylinder with the steps I’d taken.
The cylinder would need 15 bar of negative pressure to explode or implode.
Now as you’ve mentioned, I looked up on drain down of said cylinder and sure enough there is a drain down procedure.
No, I did not drain down as per instructions, so yes, working on any of the plumbing involving the drain down of the cylinder is my responsibility and liability.
Anyone who works on any dwelling is liable regardless. There should be a proper understanding of any system installation to work on it safely.
Now I have been on this forum for some time and admittedly use it to learn of other people’s experiences.
Knowledge and experience is key, so i would like to think that I don’t undertake any work without prior knowledge.
In this instance, I admit to not knowing or researching proper drain down procedure of the installation so the only way is for me to understand what I have done or what has caused the cylinder to implode. Not only this one but also the previous one.
I’ve been installing bathrooms for the last 15 years and am proud of every single installation without any major failings. Yes the odd leak in joints and fittings but not a major failure like this.
Every day we learn something new or old but I learn something every day and never have I claimed to know everything.
Anyway, back to why you’ve rightfully mentioned....... correct drain down procedure!
I’ve taken an image of the manual and have also discussed this with couple of heating engineers, one of which I know who’s installed this cylinder.
They both admit to not knowing this drain down procedure.
All I’m doing is waiting for Gledhill to get back to the plumbing merchant I use and document everything for the client to take up with the installer.
Thant you all for your input and sharing your knowledge to point out the possible faults.
I really appreciate the input