Have noticed the the Bottle Air Vent on the Primary Return pipe from my Heatrae Sadia Megaflo (indrect unvented system) to the boiler is leaking water, as the washer on the plastic cap has perished.
I've replaced the washer, and that's stopped the leak, but I'm no expert (I didn't even know these vents existed till I was forced to investigate/understand the leak!!), so I don't know how air gets vented from these gadgets.
Do they vent air automatically (i.e. may I now have also stopped the air venting from it, by putting the "wrong" kind of washer on it), or do they simply vent manually (i.e. I suppose I should be loosening off the plastic cap occasionally, in which case I guess the change-of-washer is fine)?
Thanks.