Cold Heating Radiators Upstairs

[pkewish]

I have a gravity fed system and cannot get 3 of the 5 upstairs rads to get hot at all. Not even the pipes leading to them are getting hot. Having spent hours reading various threads on this site and running around with a spanner I still haven't got to the bottom of this problem.

The boiler (glowworm flexicom HX), Pump, and control valve and water tank are less than 18mths old

I have removed TRVs ALL pins are okay, I have tried to balance system by opening values 1/8 to 1/4 turn until rads get hot. Also bled all rads until water comes out.

All radiators downstairs and 2 of the upstairs ones get very hot !!!

Other than checking the header tank level can anyone suggest anything?

 

[seco services]

have you tried shutting the two upstairs that get hot and the cold ones fully open

 

[pkewish]

Tried your suggestion, now getting the pipe to thermostat on One radiator warm but rad not heating up and still nothing on the other two

 

[gas4you]

Try turning off ALL rads except one that doesn't get hot. Check pump is on fastest speed and try again.

 

[seco services]

is the thermostatic valve fully open or working properly.

 

[algeep]

try isolating one of the cold rads drain down and open the valves into a bucket see what the flows like if its good at least its not the pipe work