is it a pump issue

[john4321]

i have a system that was installed over 2 years ago duel heat source (gas boiler and wood stove)
every time we put the heating on the overflow starts running this doesn't happen when its hot water only. we have 16 radiators mixture of doubles and singles and only 1 pump on the system that is set at its highest setting if its turned down some of the rads will not heat

question is
should i install a second pump on the ground floor return to take some of the presure off and will this resolve the issue

thanks

 

[D_Hailsham]

The system probably needs balancing.

 

[john4321]

hi D_Hailsham yep system has been balanced

 

[D_Hailsham]

hi D_Hailsham yep system has been balanced

But not very well.

Check how far open the lockshield valves are on each rad. (That's the one under the plain cap). If more than one turn open from closed (turn clockwise, like a tap to close) the system has not been correctly balanced.