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

[pedr0]

Hi all, the circuit that heats my HW tank has developed a leak. What are my options for fixing it?

* The leak is in the copper pipe run between the boiler and the tank - i.e. not at the connection to the boiler nor at the cylinder.
* It only drips through the ceiling when the boiler fires up to heat the HW. At other times, either the leak is sufficiently slow that it doesn't drip through the ceiling, or the pressure is sufficiently low that it doesn't leak at all. I haven't cut the ceiling yet to inspect.
* The boiler is a Vaillant ecoTec plus 630.
* My system is an unvented system.

One fix would presumably be to fix the pipework with solder (either splice in a new section of pipe in the case of a rupture, or resolder in the case of a poorly soldered connection).

Q1) Is this the likely best course of action, or should I consider other reliable potential fixes?
Q2) If I need to solder, how do I go about draining and subsequently refilling the indirect HW heating circuit?
Q3) Are there any compliance considerations for this kind of work - Gas Safe etc?

 

[pedr0]

I might start cutting the ceiling this weekend and will report my findings, but in the meantime I would still welcome any thoughts on the questions above.

 

[terryplumb]

Firstly you need to find the leak ,establish exactly what the pipe is connected to ,( i.e.domestic hot water ,cold water,or heating circuit,etc)
Once established you can determine what needs to be done to repair.
Water carrying pipework has nowt to do with Gas Safe .

 

[pedr0]

It's definitely the indirect HW cylinder circuit. As soon as the pump kicks in to heat the cylinder, the leak starts. As soon as I turn the hot water off at nest thermostat, the leak stops.

 

[terryplumb]

And if you run central heating ,the pipe doesn't leak ?

 

[pedr0]

Don't think so. Certainly not the underfloor heating. Will try with the rads tomorrow am. But as it stands I have a high confidence that it's the indirect hw circuit specifically.

 

[terryplumb]

If you are correct ,you will need to drain the system at least to a point lower than the level of the leaking pipe.
Is the ceiling on the ground floor ?

 

[pedr0]

Boiler and cylinder are in a loft conversion (where there are two bedrooms with rads and a shower room). Is the hw circuit independent of rads?

Edit : sorry, didn't actually answer your question. The leak drips through the ceiling of the room below the loft conversion. The boiler is at one side of the house and the cylinder is at the other, so there is a straight pipe run between the two above the bedroom on the floor below)

 

[terryplumb]

The domestic hot water that comes out your taps is separate from the water that runs around the heating circuits ( heating as in radiators, UFH ,and the cylinders coil) if that's your question ??

 

[pedr0]

Not quite, but your reply answers my question. I was hoping the cylinder coil was seperate from the radiators and ufh, only because it felt like that might have made the scope of the job smaller - less to drain etc

 

[pedr0]

... At least I will only have to drain the top floor though

 

[terryplumb]

Your boiler has one flow ,and one return pipe. They will branch off to the coil, radiators,and UFH. So although they are separate circuits ,they are all from common sources.

 

[pedr0]

OK. I understand your earlier query about the rads now. Quite weird that ufh doesn't cause the leak. Will check rads tomorrow.

 

[pedr0]

Thank you, BTW.

 

[oldbutnotdead]

The water in the coil in your cylinder is the same water that circulates through the rads and ufh so draining that leaky pipe will involve draining rads- as you say, only the upper floor though.
If the leak is in the pipe run from boiler to cylinder then crack on. If (as is quite likely) the leak is tracking from a fitting on the cylinder you're venturing into G3 registered territory (cos the thing is pressurised).