Overflow running linked to shower problem?

[jimbob1]

For about the past 4 months I have had a problem with my overflow running. I called in a plumber who replaced the float system in the cold water tank and for a time I thought this had rectified the problem.

However the problem started again soon after and so I called British Gas to investigate.

The report said that "Cold mains water passing through the shower and back-filling the cylinder is causing the header tank to overflow and also loss of hot water overnight pushing hot water out of the cylinder".

The man also said that their may be a faulty 'cassette' in the showers' control unit which is not shutting off the water. Could this be the non-return valve?

 

[Terrywookfit]

The shower should be fed from balanced supplies.

Ie, Both tank fed.

Is it a mixer tap on the bath ??

 

[jimbob1]

Yes, the bath has a mixer tap.

 

[Terrywookfit]

I meant is the shower supplied from bath mixer tap?

 

[jimbob1]

OOpps, sorry!

No, the shower is wall-mounted and independent from the bath tap.

 

[Terrywookfit]

Supplies should both be tank fed then!!