Overflowing Economy 7 Boiler

[Neil1981]

Hello

I have a direct economy 7 boiler (Range Super Seven) which has recently started to overflow on a regular basis. I have replaced the ball valve in the expansion tank on top of the cylinder and bent it to shut off sooner. However it still over flows.

Could the water be coming back up from the cylinder somehow into the expansion tank to make it overflow?

Also, the heating was controlled via a panel in my kitchen, this broke a few months ago and I have been switching the immersion on by manually switching the relays to activate the system. It would originally switch on automatically when eco 7 kicked in around midnight.

Would this have any impact?

Do I need a new boiler and if so, do I still need an expansion tank or will a cylinder suffice?

 

[kevplumb]

any mixer taps or showers fitted ??

 

[Neil1981]

Yes - though the shower I think is not on the boiler circuit. I am pretty sure that it runs off the cold water circuit as it is an electric shower, but can't be certain.

There is a mixer tap in the kitchen as well.

 

[kevplumb]

could be back feeding the mains through it

 

[Neil1981]

Both the shower and the tap has been there for over a year before this started to happen?

If this is the case, what can be done to solve it?

 

[kevplumb]

i never said it was the cause

i said it could be

run the hot then close tap you should feel the pipe go cold if its feeding back

fit a non return valve on the hot supply to the mixer

 

[Neil1981]

Thanks, will have a go at that

Cheers