What's this on my water tank?

BennyC · 5 Nov 2013 at 17:55

Hi,

Could somebody identify what this is on my water tanks plumbing? I refer to the little black open cone. I noticed the other day that water was dripping through it and was just curious if this is normal or and indicator of something to be concerned about?

Thanks,

BennyC

Gladil · 5 Nov 2013 at 18:42

It's called a tundish.

Screenbeat · 5 Nov 2013 at 20:02

Its an air break and no, you should not see water dripping past it!! One of the relief valves is passing, either high pressure or valve has not seated properly.

BennyC · 6 Nov 2013 at 12:55

Screenbeat said:
Its an air break and no, you should not see water dripping past it!! One of the relief valves is passing, either high pressure or valve has not seated properly.

Thanks,

By past it do you mean through it? as that's what was happening.

I tweaked the thermostat on my hot water tank about a bit a couple of days ago but left it set to where it was before I fiddled with it in the end.

RJC · 6 Nov 2013 at 13:00

If you see water dripping then one of the relief valves may require replacement and system pressure checked.

BennyC · 6 Nov 2013 at 13:05

RJC said:
If you see water dripping then one of the relief valves may require replacement and system pressure checked.

Thanks, pressure has been holding since I last topped it up at the beginning of the year.

Have notified the builder, the house is just out of the snagging period but I've had a fair few problems with the system so will stamp my feet if necessary.

BennyC · 28 Nov 2013 at 18:17

So I had the plumber come and replace both the relief valves the other week.

He did say at certain times, like when the pressure becomes a bit much and a few other reasons I can't remember, that water would drip from the tundish and that it wasn't anything to be concerned about. It is now almost streaming.

Pressure has always been around 1.5bar and still is.

Should I be concerned? could something else be the cause?

Where exactly does the water I can see in the tundish come from? With this dripping away fairly frequently I'm conscious of my water bill, I know the effect would be small but still.

Thanks.

I think this only occurs when the heating is firing. The waters on at the moment but will take note to see if it happens later in the evening with just the heating.

BennyC · 20 Feb 2014 at 17:53

So this is still dripping away and I've been chasing the Customer Service centre to get the plumbers to return.

If I twist either of the red valves then water gushes through, it eventually slows, (from memory) sometimes stopping. But after a while the drip returns.

I'm fairly sure this is only happening when the water is on and not the CH.

I don't know if any of the above helps to pinpoint anything in particular at all? It would be good if I could say to them for certain XYZ needs replacing.

Not the greatest video in the world, it's worse than portrayed.

Nedved11 · 20 Feb 2014 at 22:10

Turning that knob will release the pressure from your expansion vessel. Chances are the PRV will find it hard to seal again. Your plumber may charge your expansion vessel up as it may be too low. Should be just below 1bar when the pressure is completely release I.e. Drained down.

FlyingFish · 20 Feb 2014 at 22:49

Nedved11 said:
Turning that knob will release the pressure from your expansion vessel. Chances are the PRV will find it hard to seal again. Your plumber may charge your expansion vessel up as it may be too low. Should be just below 1bar when the pressure is completely release I.e. Drained down.

Right sort of logic but wrong body of water!

I had a brief read through the posts and I would say the TPRV is leaking the water through the tundish. This is most likely because the expansion in the DHW isnt being dealt with. This can be a case of recharging the white expansion vessel back up to around 7bar (while empty) or draining the cylinder and re establishing the air gap in the top of the cylinder. Depending on which system you have. You could be also looking at a faulty/badly set pressure reducing valve.

Either way your probably best getting someone in whose got their UVHW qualification to sort it out for you.

Mick

BennyC · 23 Feb 2014 at 16:53

FlyingFish said:
Right sort of logic but wrong body of water!

I had a brief read through the posts and I would say the TPRV is leaking the water through the tundish. This is most likely because the expansion in the DHW isnt being dealt with. This can be a case of recharging the white expansion vessel back up to around 7bar (while empty) or draining the cylinder and re establishing the air gap in the top of the cylinder. Depending on which system you have. You could be also looking at a faulty/badly set pressure reducing valve.

Either way your probably best getting someone in whose got their UVHW qualification to sort it out for you.

Mick

Thanks very much, I'll keep hassling the builders to get the plumbers back

dannyjo22 · 23 Feb 2014 at 19:57

I get this from time to time on mine. There are instructions on my megaflow cylinder to rectify this. He's a video version.....

From the website:

There are a number of faults on a MegaFlo that could cause water to discharge through the tundish. If the discharge water is cold it probably needs servicing to replenish the air gap above the internal baffle. If the water is hot then it is probably being caused by a faulty temperature and pressure relief valve.

Mickie · 23 Feb 2014 at 22:57

Need to check hot water temp as ones a temp relieve valve/pressure and others pressure only. I'd check the pressure reducing valve too sand obviously check the expansion tank. I always pump them upto 1.5bar with a valve open and heating drained.

It doesn't matter what anyone says. They're never supposed to run water through the dish.

Participant · 21 May 2018 at 13:41

@BennyC - sorry to drag this thread up, but I found it via Google and I have exactly the same problem (tundish passing hot water when the boiler is heating the hot water).

Did you get to the bottom of it?

I've had Worcester Bosch out twice and all they did was replaced the valves.

BennyC · 21 May 2018 at 17:10

Participant said:
@BennyC - sorry to drag this thread up, but I found it via Google and I have exactly the same problem (tundish passing hot water when the boiler is heating the hot water).

Did you get to the bottom of it?

I've had Worcester Bosch out twice and all they did was replaced the valves.

No problem at all, it was 4 years ago now mind!...

I really can't remember but it could be worth checking the thermostat on the tank doesn't need resetting. I had issues with my boiler last year (needed a new PCB) and I asked the British Gas engineer to educate me a bit on my setup.

Under a little grey box there's a tiny button which sometimes needs a 'click' so I'm told. We got to this a my water temperature was INSANELY hot after they'd replaced numerous bits in my boiler. As I say I'm told sometimes the tank thermostat can need a reset, my logic (probably wrong).

Worth a punt but more likely to be a sticky valve somewhere, have you turned the red knobs like on mine? as I think on one occasion it was just stuck open.