Several radiators don't get hot, why?

Thanks for this information.

I have tried moving the pin up and down on the kitchen radiator. In fact the pin was not stuck. So pin working and it is full of water (no air block). What would the next step be?

John
January 2016

If you have thermostatic radiator valves then unscrew the heads on your poorly performing radiators - no tools required.

They press on a small brass pin (up and down) and these pins can get stuck in the down position during the summer when they're turned off.

Just pull them up with a pair of pliers.

As for the conservatory radiator - it may be that by the time the pumped hot water gets there most of the heat has been used up - turn off all the radiators except the conservatory and see what happens.

You might adjust the boiler to make slightly hotter water and or adjust the pump to pump the water around more quickly or you might investigate how to balance radiators to even out the heat distribution.

If you measure the heat of the boiler's return flow pipe you will know the maximum heat that the last radiator in the system can reach.

Good Luck...
January 2016