Noticed a small brown stain below our Vaillant combi Saturday. Quick look underneath didn't reveal anything too suspicious. I nipped up all visible connectors, cleaned up, and waited.
Today, there was a small drop ...
Re-investigating, and I noticed above the pipework I had checked was a thing I now know to be a diverter valve.
Bit of googling suggests it's not an unknown problem.
I removed the actuator and had a peek inside, and there was a crust of rusty/cruddy solids. I managed to gently scrape this out, clean up with a soft cloth so it all looked clean
(while I was doing this there was no weeping).
Hoping that the leak was due to some crud being where it shouldn't be, I gambled a squirt of silicone into the gubbins might help smooth the seal.
Reassembled, ran DHW/CH/DHW/CH and so far no leak.
Assuming the worst, how easy is it to change the valve (which is the leaky bit). Does the actuator *need* changing, if the only thing I can get is a kit ?
cheers all.