warm water in cws tank and pumping out the overflow

[Garfeild]

If the header tank for the heating is higher than the cold storage tank,maybe the coil in the cylinder has a pinhole in it?

 

[doitall]

Could be mains water entering your system somewhere.

Do you have a shower valve that has mains fed cold, tank fed hot?

Washing machine that has both a hot and cold fill???

So your back to an mixer or shower valve letting by and back feeding into the hot.
Check mixer tap/valve with mains cold, including the washing machine.

Check these please.

An easy way to check this is to run the hot water until the pipe is hot, then keeping your hand on the hot pipe open the cold tap, does the hot go cold.

Have you changed any taps prior to the problem.

 

[kevindgas]

If the header tank for the heating is higher than the cold storage tank,maybe the coil in the cylinder has a pinhole in it?

christ it took a whole page to come to the most logical explanation!

 

[kevplumb]

vented system

err

kevplumb wrote:
is the heating header tank higher then the cold feed tank icon_question.gif


Yes FE Tank is in the loft, CWS Tank is in the airing cupboard.

err

 

[bathstyle]

I favour the mixing valve on the washing machine, had this before but admittedly only on commercial machines

 

[doitall]

I favour the mixing valve on the washing machine, had this before but admittedly only on commercial machines

And I agree, although you should consider other mixer taps and valves as well.

Blender valves for hot/cold is another source of future problems.

 

[twgas]

After drawing off the water from cws tank did/has the water level risen at a noticeable rate, I find that generally if it's a slow, overnight before it drips scenario, it tends to be coil in cylinder, a fairly quick rise, 30mins or so, it's a mixer of some sort.

Isolate the header tank in loft, and see if the level of that tank drops, if it does the chances are the coil's gone.