My radiators are only hot downstairs, what is causing this?

system out of balance.

hi-spec plumbing
January 2007

This is what I do on my vailant combi boiler, it might work on your bosch one.
Turn your system off.
Bleed the radiators downstairs first specifically the one closest to the boiler first, this will bleep most of the water out of the whole system.
Follow that by bleeding the remainder of the radiators going away from the boiler then do the upstairs ones.
Now you will get air our when you do the upstairs rads.
Make sure you get ALL the water out of all the rads.
Make sure all the rads have the valves closed.
Turn the boiler on and open the valve on the boiler to fill the rads to the level set in your boilers instructions.

Now the radiator furthest away from the boiler upstairs open the valve until all the air comes out and water starts coming out, repeat this for al the other upstairs rads.

Go back to you boiler and you will see the pressure has dropped. open the fill value and stop at the safe bar pressure and repeat the above again the furthest away rad and bleed the rad until the air is out. This should sort it all our for ya and you should have heat upstairs.

Good Luck

col
January 2007