Water dripping from overflow ~ doing my head !

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.

Reply to
Nic o'demus
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Any ideas which one? I suspect the smaller one. The header tank for the the primary.

Expansion. Water level rises as the primary gets hot and expands. Water escapes through overflow. Water level drops, is replenished via the ball valve, repeat. Not good fresh, oxygen rich, water getting into the primary...

Bend the arm of the header tank ball valve down a bit. You may need to manually to reduce the level in the tank as well. With the system hot the header tank water level should be a couple of inches below the overflow outlet.

Reply to
Dave Liquorice

Yes, quite right, the primary (ch expansion tank) is overfilling and overflowing. I will try your remedy as above. Manually reducing the level is not a problem as we have an external drain point.

Many thanks

Nic.

Reply to
Nic o'demus

I was think more of jug and bucket after adjusting the ballcock. Easier than running up and down stairs or shouting...

Reply to
Dave Liquorice

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