Torbeck valve trouble

[RichT]

My upstairs WC cistern has a bottom entry 9.5" Torbeck valve fed with cold water from a loft tank (about 10' above). A few months back the cistern began overflowing now and again with a constant drip but has recently begun to overflow as a constant stream. I've swapped the entire Torbeck valve unit but it made no difference. Thinking it could have been a duff kit, I've swapped it for a second new kit but still it overflows. I've adjusted the float but the cistern continues to fill even when the entire float is submerged! The old valve kit did not have a flow restrictor and I've tried the new kit with the high pressure FR, with the low pressure FR and with no FR but all to no avail. Surely there can't be enough water pressure from the loft tank to overcome the valve can there? I'm stumped, so any ideas would be gratefully receieved....

 

[kevplumb]

are you sure the float or arm is not catching

 

[RichT]

Yep, plenty of space either side of the float/float arm & as I haven't put the cistern cover back on, it's not being pushed down by the lid.

 

[Bas]

Look at the instructions and you should find a way to flush the pipework with the valve body in place - maybe the valve isn't as it should be.

The valve should stop the water when you lift the arm. you will hear a knock as the valve closes.(you might not with the flow restrictor in place. Leave it out.

 

[RichT]

Tried it without the flow restrictor but there's no knock when the valve closes. Having said that, the valve isn't fully closing anyway as water continues to flow through. The volume of water decreases dramatically as the float arm rises but still doesn't fully stop.
Nothing in the instructions about flushing it out, but there are only a few pieces and I've checked there's no blockages etc.

 

[Bas]

These things are normally very reliable, i've fitted hundreds. Looks like you will have to try another.