Hot water tank dripping...

Hi All,

I should warn you all up front, I know *nothing* about plumbing, so this thread may be hard work (but hopefully it's simple) :)

I moved into a new flat a few months back that has (if I remember what it's called) a storage combi boiler in - so we've the boiler in the kitchen, then a tank with immersion heater in the airing cupboard.

Missus was in the airing cupboard yesterday and noticed that the carpet was soaked through and that there was water dripping out of a pipe onto the carpet.

By the looks of it, a pipe had been knocked out of place, so I shoved it back in again.

I'll try and describe this pipe as best I can...

There are two pipes I can see going into the tank, one labelled "return" and the other one not labelled at all - it's the other one that was giving us problems. It's about two thirds of the way up the tank on the right hand side (the return is around half way up in the middle iirc) - it comes out perpendicular to the tank, then turns 90 degrees and heads downwards.

About a foot down, there's a joint with a flexi-hose thing attached at 90', which goes off and joins some other pipes - that have pressure taps on them. Immediately below this joint, there's an interesting device I'd not seen before...I call it a bird cage with a lemon juicer in it...It's made of black plastic, is probably about 3 inches long. It's cylindrical in shape, but has most of the sides cut away, so you can see inside. If you look from underneath you can see that inside, in the top of the thing, is a little inverted cone - the point of which seems to be to let drips run to the middle, then fall off down the centre of the device - I guess this allows it to drip, without it falling out of the cut-away sides - so I guess this is a "drip viewing device" or something.

Anyway, this is where the water was dripping out and there was a displaced pipe a couple of inches below, which I've popped back in here and tightened up - this goes down to a couple of inches above the floor, then heads off and disappears behind the tank. As the pipe's so close to the floor, I can easily see us putting the ironing board or something on it and knocking the pipe out, so that in itself isn't much of a concern...

So, my question, really, is just - what is this thing? What's it for? And should it be dripping in the first place?

Many thanks in advance -and well done to anyone that can decipher it! :)


  • gazebo
    gazebo Posts: 465 Forumite
    First Post First Anniversary
    sounds to me like the bit you describe is the Tundish or visual overflow

    in terms of should water be dripping through it - not unless there is a problem with your tank.

    There could be any number of things wrong - or not really anything worrying at all.

    I can't be of any more help, though would ask you if you know where the pipe that disappears behind the tank actually goes to - reason for asking, if water is dripping down through this, is it draining away to the outside of your house or is it an overflow that isn't really connected to anything thus causing a build up of water you can't see yet (I won't start telling you the luck I've had in my life with non connected overflows...).
  • Idiophreak
    Idiophreak Posts: 12,024 Forumite
    Combo Breaker First Post
    Many thanks for your reply, gazebo - you definitely seem to have gotten me on the right track - it's definitely one of those tundish things.

    The first result I came to when googling tundish took me here:

    This seems much like my setup and it's interesting and hints at another question I says "If the air gap in the heater is not replenished routinely then this will give rise to water being discharged unnecessarily via the blow off pipes."

    It doesn't really specify how that's supposed to be done, however, whether it's something I should be doing, or is done in the service.

    So my other question:

    There's a pressure gauge attached to the tank. When we moved in we were told to ensure that the pressure remained around 2500-3000 (iirc) - currently the thing's around 2000.

    When I first tried boosting the pressure when we moved, I opened the taps we'd been told to, heard it vroosh and the pressure went up steadily, then I shut it off at the desired level.

    When I've tried this lately, there's a *small* woosh, the needle moves a fraction upward, but that's it.

    Does anyone know more about this process, how to get more pressure in, whether the water should be on, off etc and the rest.

    Many thanks again!

    ETA: I'll have a look tonight and see if I can work out where the overflow's attached.
This discussion has been closed.
Meet your Ambassadors


  • All Categories
  • 343.8K Banking & Borrowing
  • 250.3K Reduce Debt & Boost Income
  • 450K Spending & Discounts
  • 235.9K Work, Benefits & Business
  • 609.1K Mortgages, Homes & Bills
  • 173.4K Life & Family
  • 248.5K Travel & Transport
  • 1.5M Hobbies & Leisure
  • 15.9K Discuss & Feedback
  • 15.1K Coronavirus Support Boards