Leak in indirect HW circuit - do I need to drain and solder?

[pedr0]

Having investigated though a downlight cutout, I can tell that the water marks on the ceiling are along a line where 2 plasterboards meet. Above is a tiled bathroom .

So the water might be coming from anywhere in a roughly 4 to 5 foot square area and then trickling to the edge of the plasterboard before being seen on the ceiling below.

The waste pipe for that tundish is in that rough area.... But so are quite a few other pipes.

 

[terryplumb]

A right pain then. Sounds like you will need to cut out parts of the ceiling

 

[HERTS P&D]

We always cut holes in ceiling on insurance call outs, as it is much safer than lifting floors due to the house holder tripping up.

Andy

 

[JohnD]

You mention soldering.

For all practical purposes, you will find it impossible to solder a horizontal pipe that has had water in it.

 

[gas112]

You mention soldering.

For all practical purposes, you will find it impossible to solder a horizontal pipe that has had water in it.

how will it be impossible to solder a horizontal pipe that has HAD water in it ?
Gets done thousands of times every single day

 

[oldbutnotdead]

Just before you start pulling the ceiling down, might be worth investing in one of those cheap endoscopes (some work with a phone, cheapies Lidl was flogging a couple of years ago have their own screen etc).

 

[pedr0]

OK. Update:
The leak is coming from the tundish.

It was hard to spot, because the water on the ceiling actually occurs when the flow through the tundish has slowed to a very slow trickle. So slow, that it no longer streams like the picture in post 25:



It's when it slows down so much that the water actually clings to the support arms of the Tundish and then over the edge and down the pipe, rather than into the dish of the tundish. It was then difficult to spot the water because it was trickling down the back of the tundish and the outside of the pipe (a constant trickle rather than a drip but with a stream of 1-2mm across, creeping down the pipe).

Is there anything I can do to either further diagnose or fix the problem?

That's a tundish ,and shouldn't have water flowing through it unless there is a problem,with hot water expansion not being accommodated ,or the PRV is passing when it shouldn't. Probably the former. Have you followed the pipe from the lower part of the tundish connection ,to see if it's leaking ?

That receptacle is called a tundish. It's there so you can see when water is flowing through it, which it shouldn't do under normal circumstances. Not sure those pressure relief vessels will work properly on their sides.

 

[Madrab]

If it's the unvented side of things then it needs an engineer in to service, as part of that the dripping @ the tundish should be fixed. Alternatively, it's the central heating Pressure Relief Valve and hopefully that unvented engineer is also a gas/heating engineer and can service that side of things. It may just be a Expansion issue which is easy fixed.

 

[oldbutnotdead]

OK. Update:
The leak is coming from the tundish.

It was hard to spot, because the water on the ceiling actually occurs when the flow through the tundish has slowed to a very slow trickle. So slow, that it no longer streams like the picture in post 25:

View attachment 289684

It's when it slows down so much that the water actually clings to the support arms of the Tundish and then over the edge and down the pipe, rather than into the dish of the tundish. It was then difficult to spot the water because it was trickling down the back of the tundish and the outside of the pipe (a constant trickle rather than a drip but with a stream of 1-2mm across, creeping down the pipe).

Is there anything I can do to either further diagnose or fix the problem?

Get a G3 registered person in there to fix the pressurisation issue that's causing the flow (various possible causes, none DIY, most not expensive).
While they are there, get them to sort the tundish out so it drains properly rather than leaking as it has been.