Hello all. First, I am no expert. I have a *conventional* heating system. Gas boiler, pumped ch, gravity hw, 2 storage tanks in loft, hw cylinder in airing cupboard. Hw controlled by cyl stat & motorised valve. CH (2 zones) controlled by room stat & manual control of zone valve. Programmer allows independant use of ch & hw. All rads except bathroom have thermo valves (if that's the right term). Whenever the boiler is on I get water dripping from the overflow from the storage tanks in the loft. This ONLY happens when the boiler is on. I have checked the ballcocks on both storage tanks, just to be sure, and they shut off well. I'm fairly sure that the coil in the hw cyl is ok because (a) the problem only occurs when the boiler is on and (b) the hw cyl was replaced 3 months ago. The boiler thermostat is set fairly low and it does not kettle. I don't think it is overpumping as the ch pump is set to its lowest setting and the problem also occurs when ch is off / hw is on. Any ideas please?
Nic.