Any heating engineers? tundish issue

Mercenary Keyboard Warrior

Mercenary Keyboard Warrior

Mercenary Keyboard Warrior

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Joined
4 Aug 2007
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Location
Wilds of suffolk
hi, so we have a megaflow and on checking the tundish it looks like its damp/maybe leaking

Longer story. Not long ago we fully decorated the kitchen and we always had an odd piece of the ceiling that felt squishy. Due to the area around it seeming to be badly plastered I figured an old repair, house is 15 years old and we have lived here over 5.

So roll on and we noticed it was damp, so tonight I bit the bullet and investigated more. Found it was on old repair and it was damp, the plaster board itself was really nasty under the patch.

Looking there has clearly been a long term leak, since there is calcium stains running down the copper pipe in the ceiling void. Following this upwards into the airing cupboard I realised this water comes from the tundish, its pretty caked up, so clearly its been an issue before leaking, if not maybe always.

Is it normal from some water to go this way, and as such could it just need tidying up and reseating (maybe replacing) as I assume its possible its just leaking round the pipe. It feels slightly damp but not really wet in there. I have the hole in the ceiling below now and also know where to look to see if its a trickle or a jet or what coming out of it.
Clearly something comes out but i am not sure when, I assume when the boiler heats the water since running hot water causes no issues.

Any thoughts suggestions etc gratefully received
 
Tundish leak is normally a sign of either expansion vessel failure, relief valve failure or really poor plumbing.

We have a kingspan system which is similar. When we moved in, the expansion vessel was plumbed in a position it could not possibly work, and the diverter valve for hot water was wrong way round. Both of these caused tundish leaks.

As the water heats up, it expands. The expansion vessel is there to allow this as the system is sealed. The relief valves (normally a red knob) will open if the pressure becomes too great. This water will escape through the tundish, normally to a pipe outside or a drain. Sometimes, the tundish cant cope with the flow and overflows, usually onto the floor!!

If you turn the hot water on, watch the tundish. It may slowly start to drip, and get worse as the water gets hotter. This normally means the expansion vessel has failed, but not always.
 
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Megaflo tanks have an internal expansion bubble which will need replenishing. The instructions to do so are on the side of the tank.

You are correct that the prv will release water through the tundish when the hot water is being heated, if the water has nowhere to expand to.

I have a megaflo and got fed up with having to recharge the internal bubble regularly, so had an external expansion vessel fitted instead.
 
Thanks guys

I am pretty sure we have an external pressure vessel as well, about the size of a football situated above the megaflow itself

Hot water came on a bit ago, so I went and watched. Pressure went to 1.5 (sits around 1.1-2 when not being heated), no sign of any weepage from the tundish
I wonder if it happens when it heats more as this only heated for a couple of mins, will check in the morning
 
What colour is your expansion vessel?

If its red, it'll be for your central heating. Unvented cylinders typically have white expansion vessels and are usually charged to 2 to 3 bar (to match your incoming mains).
 
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