Unvented cylinder constantly dripping (Ed.)

6 Nov 2022
Reaction score
United Kingdom
Hi All

Hoping for a bit of plumbing help. Our tundish is always dripping.


It always (and I mean always) drips, 24/7 but since the heating has been back on its more like a flow of water as pictured. I assume its an overflow from the hot water tank but I dont understand why it would always be dripping. There is a pipe outside our house where I assume the water runs to and the path where the water exits is almost always wet if not puddling. This has been since we moved in a couple of years ago, its just suddenly gotten worse with the cold weather and heating being on.

I am getting a plumber out but as with all things it would be amazing to understand what it is before hand so I can ensure I am getting the right assistance.

Can anyone explain to me what this is and if the severe dripping is a serious issue or not?

Many thanks in advance.
Last edited:
Sponsored Links
Sorry not a plumber but watch it doesn't freeze in this weather where it exits the house.
You have a minimum of an expansion related issue, if it was serviced annually by a G3 registered engineer, you wouldn’t have this issue.
Sponsored Links
Yup, +1 ... get someone it to service the cylinder, part of that work will be to check the EV and PRV/TPRV, any one of which could cause that.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local