Leaking overflow pipe

[Milleniumaire]

Hi, I wonder if someone could give me some advice on why an overflow pipe has started leaking.

I first noticed it about 3 or 4 weeks ago when external temperatures started falling, so the heating system was having to work harder and the leak now appears to be getting worse. Today there was a steady stream of water coming out of the pipe while the boiler was on (heating and hot water) and it is generally damp underneath the pipe outside. There are two overflow pipes near to each other and I was unsure exactly which was leaking, but it is now clear it is this one as I've seen it happening.

The 15mm copper overflow pipe appears to be connected to a valve with pipes in all directions, one of which goes to the external expansion vessel, so I'm wondering if this might need to be recharged, or if it could have failed.

Here's a few photos of the pipe work in the garage, with a circle identifying the overflow pipe that is leaking:

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View media item 70197
As you can see the pipework goes out through the garage wall and it is this pipe that I can see leaking outside.

Is this enough information for someone to give me an idea of why this overflow pipe might be leaking?

Thanks.

 

[footprints]

Looks like the safety pressure release valve leaking.

Probable causes.

1 The filling loop has been left on or is letting by into the system.
2 The valve is faulty.
3 The pressure vessel is faulty and not absorbing the system expansion as the water gets hot.

What is happening to the pressure gauge on the boiler?
Are you having to top up at the filling loop?

Regards,
footprints

 

[Milleniumaire]

Hi footprints,

Thanks for your observations.

I can confirm that I'm not having to fill the heating system and the pressure is around 1.6 bar when the boiler is running, which seems to be within the usual range, so I'm not aware of any pressure or lack of water issues, in fact apart from water leaking from this overflow pipe, both the heating and hot water systems appear to be working well!

Regards.
Paul.

 

[footprints]

If you are loosing water but not having to top up it suggests the filling loop is partly on or leaking past the tap into the system.

 

[footprints]

Just one other possible answer you say there are two pipes are you sure it's not the condensate drain from a condensing boiler you are looking at outside?

 

[Milleniumaire]

Hi, I've checked the filling valve and it is definitely fully closed so there is no extra water getting into the system.

I can also confirm that it isn't the condensate drain as I can see this is a different white plastic waste pipe coming out of the boiler.

Given that water is being lost through this overflow pipe and that the pressure of the boiler or CH doesn't appear to be affected, I did wonder if this pipe was something to do with the hot water system i.e. the boiler is also supplying a hot water feed through the hot water cylinder to heat up the cylinder. Is this also a closed system, like the CH or would this be automatically refreshed with new water if some was leaking out? I'm assuming the CH "circuit" and water heating "circuit" are completely separate.

Sorry if this is a stupid question and shows my ignorance of CH and hot water systems.

 

[Milleniumaire]

.....just to add, the other copper pipe of the two overflow pipes I mentioned, appears to come directly from the hot water cylinder.

 

[footprints]

Hard to see exactly from the picture, not too sure but it might be you have an unvented cylinder, I don't recognise it but I am way out of touch with unvented stuff, did the course about 20 years ago and never touched one since

Sorry, guess I will have to admit defeat on that one

 

[Milleniumaire]

Yes it is an unvented cylinder and was installed along with the new system boiler about 4 years ago.

Everything is made by Vaillant.

 

[footprints]

Best not to mess with unvented, it's really only supposed to be serviced by a qualified installer, with luck it may juat be a faulty valve but I would advise getting the installer back to check that's all that's wrong.
Regards,
footprints

 

[Milleniumaire]

Can anyone tell me what type of valve this is?

 

[kittedup]

It's a pressure relief valve in case the pressure reducing valve (grey valve upstream) is faulty, if memory serves me correct it's a 6 bar valve.

I expect it is either faulty or has some muck is caught on the face of the valve allowing water to drip out. You could try re-seating the valve by twisting the red cap- that sometimes works.

Otherwise you need a plumber with their Unvented (part G) ticket to replace the valve for you.

Ted

 

[Milleniumaire]

Thanks Ted. I was assuming the whole "brass valve" was a single part, but now you have mentioned pressure relief, I can see the bottom part (with the red cap) is a pressure relief valve (Grants?), and I guess this is fixed into the rest of the "brass valve" from the bottom.

Am I right? Does this look like a couple of valves connected together, rather than a single valve?

 

[kittedup]

Yes it's a separate valve

I decent plumber should be able to source and replace for around £80.

Ted