Early morning when heating has been off throughout night I notice the overflow is dripping from the header tank in the loft.
This stops when heating system is back on.
Please suggest course of action.
Thank you

Henry, May 2013

replace ball valve ,drain water from drain point until water level is just 4 in in tank ,than start boiler if water is coming out from overflow than ,its problem boiler need clean up ,power flush ,or add cleaning agent run for day than drain out ,place pump speed low

ltd, May 2013