central heating

[jcdmse]

why won't 2 of my radiators heat up

[lockman]

check that the valves are both open first, if these are ok its more than likely to be air inside, you need to use a radiator key to let the air out and all should be ok, make sure you hold a piece of rag or tissues under the key as dirty water will eventually come out.  

[sddsddean]

If that doesn't work and you have thermostat valves on each of the rads (those usually white plastic things with slots in and a ring of numbers underneath), read on. It could be the pin on the valve is stuck (this happens to at least one of my rads each year). Go to the thermostat valve and look at where the plastic body sits on top of the metal fitting. There should be a knurled collar. Unscrew it and lift off the plastic bit. You should be looking at the brass valve with a little pin in the middle. Tap the pin very gently with a hammer. You might see it pop up about 2 or 3 mm. If so, screw the valve back on and it should work. If not, its something else!!