A leaky cold water tank

Hi,

I'm new and have tried searching for the answer but it seems my problem is too basic!

We noticed one of the the down pipes for the guttering was growing a kind of mould, due to a constant supply of water running down it (and a few plants growing in the gutter!).

I've traced the problem to the overflow for a small cold water tank in the loft. It seems that the tank is warped and the water level is now just over the overflow pipe.

Firstly what is this small tank for? The water in there seemed 'old' and had sediment in the tank (which was easily stirred up just by experimenting with the ball c*ck). I run all the water in the house and couldnt make the tank empty as it all came from the huugae cold water tank next to it. (this tank is about the same size as a toilet cystern)

Secondly how to I go about adjusting the ball c*ck level so that it no longer 'leaks'.

I noticed on this site everyone says 'find the outside water supply tap before touching anything'. What am I look for here, a small man hole cover?

Any help is much appreciated!!!

Cheesey Toastie

Reply to
cheesey_toastie
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Sounds like it is the header tank for the cental heating. Adjusting the ballcock usually requires bending the shaft.

Reply to
Steve Pearce

Agree, it's a 4 gallon feed and expansion tank for the heating. If it has distorted, maybe it's had very hot water in it when the heating was running; this would indicate a fault. It should always be cold.

You probably need to replace the washer in the float valve/ballcock. It should have about 1" or 2" of water covering the outlet when the heating system is cold, leaving about 3 gallons of airspace to accomodate the expansion of the water when the system is hot. They are very frequently set up incorrectly, with 3 or 4 gallons of water when cold. The water will then overflow when the system heats up, and will take in cold water when it cools down. This will ruin the heating system in a few years.

Reply to
Aidan

What can also happen if the vent pipe (upside down U shaped pipe with open end over the tank) is too close to the water level is that water can continously pump over from the vent pipe into the header tank which then gets heated up to the temperature of water from the boiler. The plastic float valve may then burst and let in water as the system cools down, so it no longer floats and so the float valve opens and lets water in to the tank until it flows out of the overflow: this also raises the water level in the tank encouraging pumping over to continue.

Sometimes the vent pipe is supposed to be fixed to something and has come loose. It should stop just below the rim of the tank, so that it's well above the water level. It should also go up 6" or so above the level of the open end.

As Aidan says the water level in the tank should be quite low when the system is cold, maybe 3" (it will rise when the system heats up and the water expands). To maintain this level the brass rod on the float valve will usually have to be bent down.

Reply to
John Stumbles

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