Seized radiator bleed valves

Just fit new ones in the unused radiator ports?

Are they the normal type with 1/2" (one bleedable, the other not) plugs? Take the whole plug out with a rad key and replace.

I've generally kept a few plugs when I have been removing/replacing radiators, you can buy the new style, not sure if you can still get the old solid brass version ...

Silly question, but when you say 'the normal keys' are you referring to plastic or metal keys? The plastic keys are wholly useless.

Oh when they sieze, they sieze. I broke four keys of different types trying to remove one.

As are the die cast metal ones. A steel one may distort when enough leverage is applied, but it won't break.

I thought the brass ones with a pin through the end were strong enough, but when I had a seized valve, the cylindrical part split open along the length.

And often so are some of the metal ones. I've had some made of a silver coloured coarse grained cast monkey metal that has broken when used with a pair of pliers to get extra grip. I prefer the brass ones with a large area for gripping.

OR

With some older radiators, the bleed valves are installed on a blanking plug. You can change the whole plug. At 17 years old, the radiators may well be knackered anyway. You could try applying heat and penetrating oil.

Have you tried fractionally tightening them first?

I've tried all the suggested ideas, except for applying heat as that would damage the paint finish. I have ordered the suggested keys, though I don't hold out much hope. I guess I will have to bite the bullet and get the radiators replaced. A job I would have gladly done myself yesteryear, but sadly time has caught up with me and I can no longer do the things I used.

Sounds like you're unfamiliar with the existence of ss self tapping screws & washers.

NT

B&Q sell the same type, it opened one of my seized ones, the other rad was the type with the bleed valve on the back and I happened to have a spare "normal" one, so replaced the whole rad.

Percussive persuasion? Tap the end of the valve with a hammer, with a suitable bit of metal between the hammer and the valve head.

If there is enough room insert a (modified) radiator key into the chuck of a cordless hammer drill and use the hammer function to undo the valve/screw.

If a 1/4 inch drive socket set is available one of the sockets may/will fit tightly over the square and using the ratchet handle will give more leverage. If the socket set has the 6 point star type sockets rather the one with hex flats it is more likely to fit.

Freezer spray rather than heat to loosen although this may not do anything as the radiator/bleed value is probably temperature cycled on a daily basis this time of year.