why do i have to keep topping up with water on my combi boiler gauge keeps dropping into the red

petr blower, January 2010

for clarity - u dont want to see much water coming from overflow - eg only few drips as such - not an amount that will reduce the pressure ur getting - also check the valve that discharges the heating system on your central heating system to check not opened/leaking

eddie, January 2010

firstly have you checked for leaks?charge up system and go round all rads removing any air-do this a few times -when topped up check if water being discharged through overflow - the water has got to be going somewhere - make sure when charging system through fillling loop that you shut them off when complete.
Thats a first answer - there are probably others to follow from others but you need to advise boiler make/model to make it a bit easier

eddie, January 2010