My tank runneth over!!

[noisyneighbour]

Here's one to get u thinking!!
I run a basic open type gas fired central heating system with boiler (with stat), rads, room stat, 3 way motorised valve, cylinder (with stat), pump and a wiring centre box.
There are 2 probs (may be connected, may not).
1. When the system is running hot water pours out of the vent pipe into the expansion tank in the loft.
2. There's no hot water in the taps but I strongly suspect a wiring fault between the 3 way valve and the wiring centre but I could be wrong and the problems could well be connected.
Any ideas would be gratefully received!

 

[Slugbabydotcom]

Take a read of THIS and with respect to item 9 there remember that we could see if you post a picture

From what you have told us I would say that your vent pumpeth over and there is indeed some sort of problem with your diverter valve of unknown manufacture whether it be wiring or the fact that it is wrongly fitted or stuck.
Let the air out of the vent between the DV and the cylinder

 

[noisyneighbour]

Thanks Slugbabydotcom I'll give it a try