Need help with a mystery outflow on rear wall of house

[AVR2]

Our neighbour asked - very nicely - if we had some kind of outflow on the back of house, because he was seeing water seeping under the fence. I looked behind a large heavy wooden settee thing that hasn't been moved in a couple of years and saw this:

It's dripping very slightly, but persistently enough to keep that area wet. As can be seen there is no drain under it, just the paving slab.

Can anyone identify it? Would the persistent dripping indicate a problem somewhere, or is it working normally and we just need to seal under the fence to keep the neighbour happy?

 

[JohnD]

what is the diameter of the pipe?

what is on the other side of the wall? A boiler? A kitchen? A WC?

 

[AVR2]

It's 32mm. There's nothing on the other side of the wall at that point - the piping that leads to it is inside the wall. It's the back wall of the conservatory - nowhere near a boiler or WC. The conservatory opens off the kitchen, but that part of the wall is diagonally opposite where all the kitchen water supply stuff is.

 

[JohnD]

so perhaps it is upstairs?

That is a large pipe, and too big to chase into a wall safely. It may be (incorrectly) hidden in the wall cavity.

Start by telling us where the boiler, kitchen and bathroom are, in relation to that pipe

clean the paving where it drips. Is the concrete eroded?

Have you got a hot-water cylinder? Is it white?

Do you have water tanks in the loft?

Show us the outside wall, all the way up to the roof please.

Is there an extension, or a flat-roofed porch?

 

[Burnerman]

The pipe couldn’t run under the floor, could it?
John

 

[AVR2]

Here's the back of the house. Next door has a corresponding outflow on their side of the fence, which is completely dry underneath.

No erosion on the paving under our outflow.

We don't have any tanks in the loft. This is our hot water cylinder, on the landing next to the bathroom:

I don't know if it's purely coincidental, but we have a drip from the filler inside the cistern in the closest toilet above the outflow at about the same pace as the one from the outflow. I hadn't noticed it before. Could they be connected?

 

[HERTS P&D]

Post a picture looking into the toilet cistern.

Andy

 

[JohnD]

where is that cylinder, in relation to the pipe?

 

[AVR2]

where is that cylinder, in relation to the pipe?

To the right of the window marked "Toilet/bathroom", and several feet away from the outside wall. The foot of the bath is under the bottom of that window, the cylinder is roughly where the head of the bath is (pointing towards the front of the house).

The bath is currently in use, so will post a shot inside the cistern later.

 

[Gasguru]

It's probably a 28mm pipe with an elbow from the unvented cylinder tundish....have a look in the airing cupboard.

 

[AVR2]

Bingo! There's a drip through the tundish.

That's annoying, as the cylinder was only replaced about 18 months ago.

 

[Hugh Jaleak]

I'd hazard a guess it's the outlet from the PRV on the Cylinder. Edit, found the issue!

 

[AVR2]

Yes, there's a drip through the tundish.

As mentioned above, the cylinder was only replaced about 18 months ago as the final solution to a problem that started with us noticing a rushing water noise. That's when we first discovered what a tundish was - there was a proper stream of water through it then.

 

[AVR2]

Thanks all - so does this likely mean the PRV needs replacing? I'd hope that such a new cylinder wouldn't have any more serious issues.

 

[Hugh Jaleak]

Possibly only needs the expansion vessel recharging, unlikely to be a fault with the cylinder itself as such. The PRV is a safety device to release excess pressure safely, it may be fine again once the pressure issue has been resolved.

Unvented cylinders are supposed to be serviced annually, if it hasn't been done then may be wise to get it checked over and repaired as required. If you haven't got anyone in mind, look for an engineer with a G3 certificate to work on unvented.