by barryrk »
Tue Jan 19, 2016 8:52 pm
32 year old indirect system, oil fired with new boiler about 7 years ago. My system was recently drained and refilled after a leak was found in the central heating system. Since then the system pumps hot water up the supply pipe once the central heating thermostat turns the heating valve off. The hot water system stays charged. In effect it syphons water out of one of the radiators. Is this caused by a blockage or airlock? I have a Magnaclean fitted which collects deposits regularly. I have reduced the cylinder thermostat setting. The system will not bleed once the pump (new) is off.
