Alpha CB28 dripping under flow switch

[Grubby]

Hi, I need help! My boiler kept losing pressure to the hot water and needing topping up with the filling loop. I noticed it had been dripping, only a little, but getting worse.

I opened it up and it is dripping from a small hole under the flow switch, next to the diverter.

I have no problem with hot water or heating when it has pressure.

I removed the flow switch, had a small amount of black on the base, and refitted. Has maybe slowed the drip a bit, but maybe not, not sure.

Is this a flow switch problem or is it the diverter causing this? Could really use some advice, please ask if more info is needed!

Thanks

 

[45yearsagasman]

There is an internal seal which has failed. Replacement of the seal involves removal and dismantling of the valve (horrible). Some say use leak sealer, but I do not subscribe to that. New diverter or if you feel confident replace the seal. I'm not sure of the part number.

 

[Grubby]

Thanks for the reply! Where would I find a part number?

Edit - is this it - http://www.boilerparts.co.uk/SparePartDetails.aspx?manu=ALPHA&partno=3.013391

Seems I might be getting bits I don't need. Will a local merchant likely carry these o rings in the boxes they keep, or is it a specific size? Don't want to dismantle it to find I cant repair!

 

[45yearsagasman]

Let me put it this way, I've attempted one time to repair this valve when it leaks from that seal. Never again. Most other div valves are repairable, but this is one instance where a new valve is the better bet.

 

[miggy]

Agreed, can be a pain specially if the tiny soft phillips screw underneath has corroded. All depends on how long it has been leaking. Not!! a diy job. Need someone who is confident at repairs. Have done many of these. If leak is caught quickly it limits damage and old valve is serviceable. If it has been left weeping for a long time, then makes job awkward.

 

[Aquilani]

quite common on these, as said above it can be a bit of a pain to change if the water has corroded the grub screw.