Venting problem

[Elitepm]

Hi All

I'm in the middle of a bathroom re-fit and am changing the old rad for a towel warmer. This involves moving one pipe and changing the valves.

Normally, I try to create an air lock to temporarily stop the flow by blocking the vent pipe and the outlet of the F&E tank. However, whilst trying to run off a couple of buckets of water I noticed that the main cold water tank was emptying?? No other draw-offs were open. So I decided to turn off the mains and empty all the water from both tanks. On re-filling I noticed that the F&E was overflowing. On inspection I found that it was full with luke warm water which makes me think that the boiler is venting and that the ball valve was OK.

Anyone know why the rads might be fed by the cold water tank? Maybe it's just the one in the bathroom? Also, what would cause the venting, how dangerous could this be and how is it cured?

Thanks in advance

Brian

 

[chrishutt]

Sounds like split in coil heat exchanger in your cylinder. Which is higher - the CH header tank or the Cold water feed tank for the hot water cylinder?

 

[Elitepm]

The cold water tank is higher than the header tank

 

[chrishutt]

Then that fits with the symptoms you describe. You could verify it by isolating the cylinder coil from the CH circuit (which will stop the overflowing). You will need to replace the hot water cylinder.

 

[Elitepm]

Cheers mate