Thanks for reply.
I think my worry is that because they don't seem exactly the right size and not fibre that they will leak like a sieve?
The main issue is that the whole system has to be drained (again) if the washers don't hold...which means a right mess!..again!
I am tempted to just...
Changed a diverter valve (on a sime boiler) at 8pm last night.
BUT...as it was a right pain to physically get to, I removed the water pump.
Now....On re-filling the system one (or even 2) joints leak on the pump...and I mean leak...it pours!!
Ok...just new washers (maybe)...but on a...