Long handled 5 mm square radiator key

[einhorn]

I tried to bleed a radiator using normal rad key, no joy. Bleeding screw head is 5 mm square. Its not been unscrewed for ages.

Does anyone know if there is a long handled rad key to provide extra purchase?

One thing that does give me some cause for concern is when using a long handled implement just how much force should one use without causing damage?

I was thinking of adding some penetrating type oil first although have my doubts if enough can get to the working mechanism to do any good! What do you reckon and is there any product that anyone has used successfully in this application?

Many thanks.

 

[steadyon]

1. Use a spanner / pliers with an ordinary key to increase torque.
2. The screws are often made of brass, so it won't take much to shear it.
3. More likely to be 3/16" than 5 mm.

 

[WC1]

Would say go for it, needs doing and it's usually pretty easy to change the bit that the bleed screw goes in to if it shears off.
Or could try bleeding via loosening the nut on the opposite end of the rad.