Can someone tell me what this plastic thing is and does in my airing cupboard?

[blueplanet]

There is black plastic thing in my airing cupboard that has hot water going through it. Its been there for years and I have never seen water going through it. Today I had a loud noise in my airing cupboard (like water dripping) and noticed that it had water going through. It doesn't seem normal as its too loud.

I have gas-fired boiler and an indirect unvented Joule cylinder installed in 2017 if that's any relevance. Please see the attached video and the black thing is to the right-hand side. Thank you.

 

[gpbeck]

The video doesn’t work for me but I’m guessing you might be describing a tundish (google it) which passes water if your hot cylinder is over pressure, possibly boiling! If it is a tundish, turn off any possible water heaters (electric immersion heater and/or boiler) and the flow should stop. This is potentially very dangerous and you need an emergency plumber with special qualifications to resolve the problem. Do not turn any heating back on until a plumber has been.

 

[blueplanet]

The video doesn’t work for me but I’m guessing you might be describing a tundish (google it) which passes water if your hot cylinder is over pressure, possibly boiling! If it is a tundish, turn off any possible water heaters (electric immersion heater and/or boiler) and the flow should stop. This is potentially very dangerous and you need an emergency plumber with special qualifications to resolve the problem. Do not turn any heating back on until a plumber has been.

Thanks, Yes it is the tundish. I had the hot water on (via the timer switch) but the heating was off. Will this be linked to a failing boiler or just something to do with the cylinder needing changing? Thanks.

 

[gpbeck]

Perhaps a faulty immersion heater, faulty boiler, or a faulty safety valve on the unvented cylinder. Doesn’t matter, advice is the same. No heating, flow should stop. Get help. These things can literally explode. Tanks often have an electric immersion heater that people don’t use or even know about.

 

[blueplanet]

Perhaps a faulty immersion heater, faulty boiler, or a faulty safety valve on the unvented cylinder. Doesn’t matter, advice is the same. No heating, flow should stop. Get help. These things can literally explode. Tanks often have an electric immersion heater that people don’t use or even know about.

Thanks, definitely note the immersion. I very occasionally use that so know where that is and I checked to make sure that was off. So could be one of the other items. I will turn it off. I think its a G3 qualified person I need. Thanks for your help.
[automerge]1602194037[/automerge]
OK, I checked the pressure gauge and it was a higher than where it should be (it has a marker on the correct place). I have turned it off. I will be getting (hopefully) a new cylinder in a few weeks when I have solar thermal installed so I will ask them to check and resolve the issue at the same time. Thanks again.

 

[gpbeck]

Thanks, definitely note the immersion. I very occasionally use that so know where that is and I checked to make sure that was off. So could be one of the other items. I will turn it off. I think its a G3 qualified person I need. Thanks for your help.
[automerge]1602194037[/automerge]
OK, I checked the pressure gauge and it was a higher than where it should be (it has a marker on the correct place). I have turned it off. I will be getting (hopefully) a new cylinder in a few weeks when I have solar thermal installed so I will ask them to check and resolve the issue at the same time. Thanks again.

Where is this pressure gauge and what is the number?

 

[blueplanet]

Where is this pressure gauge and what is the number?

I will attach some photos. There are two bubbles one red and one white. The gauge is on the red on. I have turned the system off either off. One of the photos shows the tundish and the other the gauge.

 

[gpbeck]

Sorry doesn’t help unless you know what the reading was when the tundish was passing.

 

[blueplanet]

Sorry doesn’t help unless you know what the reading was when the tundish was passing.

It was above the red dial, I have marked it in red where it was on the attached photo. I brought it down below. Thanks.

 

[oz-plumber]

The relief valve shouldn't be passing at those pressures.

Time for new relief valve and maybe expansion tank pressure.