Plumbers/heating engineers - what is this called and why is it dripping?

Andr3w · 15 Jan 2017 at 17:04

I've noticed that this 'overflow pipe'?? Has started dripping....quite a lot.

I seem to remember asking a plumber once and they said it should never drip.

It is dripping a lot - at least 2-3 drips per second.

Any ideas what could have caused this? My googling failed me.

https://imgur.com/gallery/Rw5uh

Edit: I've found out its called a tundish. It has dripped before but never this much.

Edit 2: is this at all dangerous. Should I turn my boiler off to stop it heating the water?

grahamjenks · 15 Jan 2017 at 17:27

Well I'm pretty sure its not dripping gas...... It's on a hot water tank not a boiler.

It's some sort of overflow protection (basically its forming an air gap so that it can't feed back into the supply - I think...).

Can't tell you why its doing it though

Andr3w · 15 Jan 2017 at 17:30

I know it's a hot water tank but the water is heated up by the boiler, which causes pressure.

MonsterMoshi · 15 Jan 2017 at 23:38

It's not dangerous don't worry. The tundish is just to make it visible that water is coming through the pipe as it is a sign of a problem. It just goes off into the drain
Usually this is caused by a faulty blow off valve (the elbows with the red cap). They are designed to release the excess pressure if your tank was to over pressurize but that normally results in a more significant amount of water. The dripping suggests that the valve is faulty and needs replacing
Worth getting a plumber in to take a look but I wouldn't bother turning your boiler off

img · 15 Jan 2017 at 23:44

I have had this issue twice now and it just gets worse. my setup looks same as you. first time my plumber had to replace the whole valve setup as it came as a single part along with one of the units above the tank that I forget the name of. next time he replaced the valve and the whole assembly with one he made himself along with the putting a reducer in. he said lots of the new builds have this issue as mains pressure is high and these are rubbish. loads of people have had same issue here

FlyingFish · 15 Jan 2017 at 23:48

Probably best to get a plumber in to fix it. You have 3 prv's going into that tundish. So you could be looking at various reasons for dripping. Any of the 3 prv's, either of the expansion vessels, faulty thermostat, fault pressure reducing valve.

Andr3w · 16 Jan 2017 at 08:04

Jesus, just a few things that could be faulty then!

I have the details of the guy who installed the system, I'll see if I can get him to come over this week.

Those of you that had a similar fault how much did it cost to rectify?

FlyingFish · 16 Jan 2017 at 08:09

That's a piece of string question

if it's just a vessel recharge then just hour callout, if any of the valves are required then parts on top and fitting time. If your using the guy who installed the setup, then you should be fine for getting it done as he will hold his UVHW qualification.