Hi all
I've agreed to do a simple job for a friend on their plumbing system - they have a weeping joint on the domestic hot water, so a simple isolation of the system and replace the joint. They have a boiler downstairs feeding an unvented cylinder in the loft. I didn't see an expansion vessel so I assume the cylinder is a megaflo or similar with an internal expansion.
There's no isolation between the feed from the unvented cylinder and the leaking joint, so in order to do this job I'll need to isolate the feed to the cylinder and effectively de-pressurise the cylinder.
Easy I thought - but since then I've been reading about how unvented cylinders are G3 appliances and shouldn't be touched by unqualified persons, so I just wanted to check that what I'm proposing to do sounds OK. I think I'm just paranoid from the rare news articles of these cylinders going badly wrong - but I'm not going to be touching any of the controls or pipework relating to the actual cylinder so I think it is just paranoia.
So my plan is:
- Isolate the gate valve on the cold feed to the cylinder
- Open a hot tap downstairs and wait for the pressure to drain off
- Repair the leaky joint
- Reopen the gate valve on the cold feed to the cylinder
- Wait for hot tap to stop spluttering
- Job done
And that should be it... Do I then need to follow the instructions for recharging the internal air gap in the cylinder through the TP valve (which again I understand is a job designed for the user to be able to do?) or is that unlikely to be necessary?
Thanks,
I've agreed to do a simple job for a friend on their plumbing system - they have a weeping joint on the domestic hot water, so a simple isolation of the system and replace the joint. They have a boiler downstairs feeding an unvented cylinder in the loft. I didn't see an expansion vessel so I assume the cylinder is a megaflo or similar with an internal expansion.
There's no isolation between the feed from the unvented cylinder and the leaking joint, so in order to do this job I'll need to isolate the feed to the cylinder and effectively de-pressurise the cylinder.
Easy I thought - but since then I've been reading about how unvented cylinders are G3 appliances and shouldn't be touched by unqualified persons, so I just wanted to check that what I'm proposing to do sounds OK. I think I'm just paranoid from the rare news articles of these cylinders going badly wrong - but I'm not going to be touching any of the controls or pipework relating to the actual cylinder so I think it is just paranoia.
So my plan is:
- Isolate the gate valve on the cold feed to the cylinder
- Open a hot tap downstairs and wait for the pressure to drain off
- Repair the leaky joint
- Reopen the gate valve on the cold feed to the cylinder
- Wait for hot tap to stop spluttering
- Job done
And that should be it... Do I then need to follow the instructions for recharging the internal air gap in the cylinder through the TP valve (which again I understand is a job designed for the user to be able to do?) or is that unlikely to be necessary?
Thanks,
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