No heat downstairs

[stillf]

We have a problem with the central heating not working downstairs though everything is fine upstairs. I have looked through your FAQ and done some of the things suggested in there (with the help of my dad who is a recently retired heating engineer).

The boiler is a Vokera syntesi 25e and was working fine last year and nothing has been done to the system since. We have checked the pressure in the pressure vessel, following the instructions in the manual and opening the relief valve and the pressure is 1 bar (manual says 1bar =/- 0.1 bar). We have had the pump off and checked that it works and without putting a lot of pressure on the pump I can't get it to stop.
We have gone round all the radiators and bled them, we have closed off all the radiators to try and 'force' the hot water to the downstairs radiators but nothing seems to work.

Does anyone have any idea as to what else could be causing the problem as my dad is completely baffled

 

[buck51]

Do you have thermostatic valves?
Have you checked the lockshield valves are open?

 

[stillf]

All valves are open

We have taken the top off the thermostatic valves and the 'needle' moves up and down freely and isn't stuck

 

[Charnwood]

You say all valves are open, but have you tried balancing the radiators?

 

[stillf]

We have tried closing all the radiators to get the flow to the downstairs. Currently all the radiators upstairs are on reduced flow as they don't need to be fully open, the only two that are fully open are the downstairs 2, but there is no heat in these what so ever

 

[buck51]

Shut one of the radiators off, With the problem,
Remove the vent plug, put half inch iron to copper with a bit of tube connect a hose.
open flow valve. open filling loop till it flows clear.
Then shut flow and open return till the flows clear
If either dont flow full bore and clear you have a blockage or a valve shut somewhere.

 

[dcawkwell]

Shut all radiators off upstairs. Radiators downstairs should get hot.
If not you have a blockage or flow problem of some sort.

 

[stillf]

Thanks for all your suggestions.

Ended up taking the floorboards up downstairs and found a pipe that was sagging. Cured this by refastening it to the joists, drained the system down through the same side of the system that had the pipe problem and a large amount of air came out. Refilled the system and all appears to be OK now