Overflowing F & E

Hello all,

I recently got called out to a friends house who had hot water spewing out of the vent pipe above the cold water storage cistern (cwsc). This is turn caused several holes in the cwsc, resulting in a downpour of water.

Anyway I put this down to a faulty immersion (think the old ones didn't have a safety cutout on the thermostat?).

Replaced the cwsc, replaced the immersion.

All seemed fine.

Until this evening. There's water spewing out of the vent pipe to the F and E tank. Nothing coming out of the cold feed, but noticed the cwsc trickling water down to the cylinder below. A quick check of the house indicated no hot water demand at the taps / washing machine etc. Also the water only overflows when the CH is on.

In the meantime I've turned down the temperature of the boiler in case it's simply getting too hot.

All suggestions welcome!!

Cheers

pumping over?, knackered boiler stat? pump set too high? blockage.... etc etc etc

Thanks Dave, what's my best course of action to determine the exact cause. I'm not going to touch the boiler if it's anything to do with that or zone valves etc.

Think I might leave this one to a CORGI engineer...

Dont mean to sound patronising but you did plumb the cwsc in correctly?
How long is the boiler on for before water starts coming out the vent? Its is steaming water or just a continuing run of water?
What speed is the pump on? Try turning it down.....

Yeh I'm confident the CWSC is plumbed correctly 22mm cylinder feed at bottom, cold mains feed at top, overflow at top, cylinder vent above?

FWIW, the cold feed for the F and E Ts off the feed for the CWSC, not that I think that's relevant.

The water sort of gently spews from the F and E overflow, and starts then stops. Wondering why theres water being drawn from the CWSC tho, when theres no call for hot water anywhere (all cold taps are mains fed). Was thinking maybe a cracked coil in the cylinder, but then surely the F and E would be constantly overflowing, not just when the CH is on?

Cheers

Coil could be cracked....
The ball valves in the F&E and CWSC would shut the supply off when they are both full...
stick the pump on and you could cause a movement in water which would mean the level in the cisterns drop and hence keeps filling.

I'd get someone in to look as its difficult to try and diagnose anything without having a butchers..

Fair dos! outside my remit this one i think.

Cheers