I have Vaillant Pro 28 and I would like to fill up the heating system. Any directions?
It is very important to always keep the heating system topped with water to avoid damaging the boiler. You can fill up the heating system yourself in a few simple steps, use the filling cock (a device that fits into the heater) to put tap water into the heating system. You can reassure you got the right balance by checking the filling pressure display on the screen. The best level of pressure is between 0.1 and 0.2 bars.