Do I need to replace a radiator valve? ?

They don't fail that often - most usually the plastic control knob breaks.

One valve will be the regular control valve that lets the hot water in and the other end will be what they call the lock shield valve that lets water out.

Take off the plastic lids/control knobs and open them both up with a pair of pliers (anticlockwise).

If a replacement valve is really needed you will have to drain the system so let's hope it's just the plastic knob that's broken.

See also Balancing Radiators here....

http://www.miketheboilerman.com/balancing.htm

Peccavi
February 2009