New vents

Just moved into a flat and all the rad vents are virtually round,one is almost a perfect circle. Can new vents be bought? where from and are there various threads?.....Thanks

standard item at any plumber merchant - standard thread as well.

To replace turn close the valves at both ends of the radiator before removing the old one - you will get a small amount of water out of each rad so cover your carpets and get ready to catch it!

If the bleed nipples are actually fitted into the back of the radiator as oppossed to the end of it, you will be very lucky to get them as they are not a standard size (getting them out is interesting as well)

There are 3 or 4 common, different, threads !

Just my luck.. the vents are at the back..also my brother brought me a spare from his new system prior to fitting...and the thread seemed to be different

Apparantly trivial issue but a damn frustrating one !! I fitted a brand-new radiator last year costing 120 or-so quid and the bleed nipple sheared with hardly any force applied. The best design I have found since are rads fitted with nipples having a groove to take a flat screwdriver - which is handy in-case the square gets rounded or your radiator key splits at the corners. You can also get the type where the nipple is screwed into a larger sleeve that can be removed with much greater ease using a small spanner.

The thread is not standardised but definately should be. Talk about "for the want of a shoe the horse was lost" Luckily I haven't had an air-lock in that part of the system - yet.