Leak from Water tank, coming out Tundish...I think

Ok plumbing is not my thing at all, noticed staining to sitting room ceiling and it sagging slightly so thought bath or water tank, went upstairs and damage had been done, obviously had been quite a bit of water.

We have a Heatrae Sadia Megaflo tank and the water had been overflowing from the tundish think it's called.

I shut off the mains supply to the house, there was a diagram showing a cold supply that should be in the vicinity but only seen a red wheel to turn so closed that anyway.

As we have been subject to -20 and the like where we are what is the likely cause of this, overflow frozing causing pressure build up?

I have gone outside and looking for your run of the mill overflow but cant seem to see anything, maybe hidden behind icicles right enough.

Any advice greatly appreciated.

When you say overflowing from the tundish, is it full bore peeing out everywhere (bearing in mind water should be able to flow from D1 pipework to D2 pipework freely full bore).

Do you have 2 pipes from 2 different valves leading to your tundish, or do you have 2 seperate tundish?

Highly unlikely it has frozen in your D2 pipework as there is no trap, it would only occur if your discharge pipework was badly installed and the correct falls hadn't been met, which ended up with a section of pipework sitting with water in it.

Just needs air bubble remaking. The instructions for doing so should be on the tank.

Turn off mains water, either at combination valve or main stoptap.

Open HW taps

Once water stops, open relief valve on side of tank It will gurgle and glug for a while.

Once its gone quiet, close relief valve and turn back on mains water.

When it comes out the taps, turn them off!

Job done.

If that doesnt work then you need a plumber qualified to work on unvented to investigate further.

John506 said:

Highly unlikely it has frozen in your D2 pipework as there is no trap, it would only occur if your discharge pipework was badly installed and the correct falls hadn't been met, which ended up with a section of pipework sitting with water in it.

Click to expand...

The water will easily freeze if its constantly trickling from the prv. Had one last year that froze for about 3 ft of external pipe.

Thanks for the replies, here is a photo of the set up :



The chipboard was soaking all round the tank and had went through to the ceiling below, John I'm guessing it was all coming out the tundish as it was full to the top when I looked but has since gone after shutting off the supply and running the taps.

I see that instructions written on the tank Pablo but that wont make a difference if there is a freeze would it?

Also read somewhere that the method on the tanks is not the best, something about putting a hose onto the drain and getting better results.

although old thred ...hope this helps others ..

I have now installed Stelfow pressurized cylinder for some 15 months and Tundish started leaking within weeks.,Hot and cold.

So why ?? well first make sure installer has followed instructions to letter when fitting .

the problem will occur more and more as Monobloc taps ,showers etc let by if not pressure isolated.

Once the leak starts,the combined pressure valve becomes faulty and your presssurised bottle will be full of water,as seal is compromised.

But one of the most important thing is to check your incoming mains water pressure,as anything above 3 bar is the main cause of leak ,atleast with RM cylinder products. (some products amy have higher preesure tolearnce)

Having replaced valve and Pressure bottle on 2 ocaasions ...problem was still there..what a nightmare.

So after much head scratching fitter,making enquires,the fix was finally,putting on a,pressure control valve and setting to 2.8 Bar,ATTACHED TO THE MAINS WATER PIPE COMING INTO HOUSE,this way you don't have to work out where the issue is ,now you have a max of 2.8 Bar coming throughout house and will meet requirement of cylinder manufacturer.

So now having replaced(3rd time) ,pressure bottle,combined pressure valve on tank and on this ocassion, attaching the new pressure valve to the mains incoming pipe,seems have to have finally resolved the issue.

Main issue are the Monobloc fittings ,which are now commonly used and also water softener can cause issue.

Other things obviouly ,you may have faulty pressure bottle or it may just need repressuring.,but once this happpens the darn pressure control valve (califi in our case) goes faulty as well .