Combi boiler leak

Rebel61

I have a 6 year old Baxi combi boiler which constantly needs the pressure topping up. After topping up to about 1.0 bar, it then leaks slowly, dripping from somewhere at the back of the boiler, taking about 24hrs for the pressure to drop to zero again. I've collected the leaking water, which is clear and amounts to a couple of cups each time, so I guess this is just the water added when topping up. Strangely none of this seems to affect the operation of the central heating, which works fine even when the pressure guage shows zero. So, what's the problem...& does it matter?

I_have_spoken

& does it matter?

Err, yes!

Maybe the expansion vessel is leaking, so boiler will fire and run so long as the safety thermostat isn't tripping. Running the boiler will also temporarily boost pressure as the water expands.

Longer term, you'll also flush all the corrosion inhibitor out by constant re-filling.

southcoastrgi

& ruin the boiler by running it with no water in it, get the leak fixed & at the same time the low water pressure sensor (if it has one)