Overflow gushing water when mains turned on!

[Mattsky]

Hi there. Any help appreciated with this one.
I've had no hot water coming from the kitchen mixer tap, so I adjusted the cylinder mechanism in the tap so that hot water flowed OK.
However, when I turned the mains water back on, the overflow pipe outside began to gush water.
Looking at the cold water storage in the loft, with the mains turned on, there's water coming from the top-most pipe in the tank which is causing the overflow problem. (I think it's the pipe that's coming from the hot water cylinder?) Currently I have the mains turned off. Wish I hadn't meddled with the mixer tap! What to do now? Any help appreciated.

 

[Best]

Sounds like your mains water is pushing through the tap into the hot.
What exactly did you touch on your tap?

 

[SJB]

If you've got an isolation valve on the hot feed to your kitchen tap turn it off. Turn your mains back on and call a plumber in.

 

[Rckape]

Hi Matt, I'm not really sure what you've done there but Best and SJB have hit the nail right on the head.

Sounds like a job for a plumber.

 

[spanner]

Had you adjusted the hot water tank thermostat?

 

[spanner]

Had you adjusted the hot water tank thermostat?

Try to isolate and get a plumber in

 

[kris]

This is why folk shouldn't tamper with things they don't understand lol, we can all rewire a plug but to understand what goes on inside the plug is a different ball game ,,,,
Either best is right and its forcing up through the hot supply or your ballcock is jammed down when u emptied the attic tank, I'd check arm in the tank is free if so call a plumb,

 

[jaydebruyne]

If you have isolation valves under your tap, turn them off and switch your mains back on. If the storage tank no longer floods, you know you've buggered your tap. I agree with post #2, sounds like the cold is pushing back through to the hot and up through the vent pipe.

 

[Mattsky]

Hello folks, genuine thanks for your thoughts. The plumber had recently fitted a bypass valve (to clear an airlock) which indeed was forcing water up through the hot tap. Closed it off and all back to normal. Phew.