Help: Vaillant Combi Boiler - Pressure Pin (No hand valve)

[Wingman30]

I’m trying to increase the air pressure in my Vaillant combi boiler, as the pressure is currently low.

This particular model doesn’t have a hand valve for topping up the pressure. Instead, it uses a small pin that you turn on and off. In the past, I’ve used a radiator key to operate this pin, and it’s worked fine. However, today the radiator key doesn’t seem to fit—it feels too big for the pin.

Does anyone know how to top up the pressure using this type of pin? Should I try a different tool, such as an Allen key?

 

[CountryFan]

Ok, firstly it’s water you’re adding, not air. That looks like it’ll be similar to the drain off on an Ecotec, which is a 7mm open ended spanner or 8mm 12point ring spanner - you could also use an adjustable spanner.

 

[Wingman30]

Ok, firstly it’s water you’re adding, not air. That looks like it’ll be similar to the drain off on an Ecotec, which is a 7mm open ended spanner or 8mm 12point ring spanner - you could also use an adjustable spanner.

Thanks for the suggestion. I tried using a 7mm spanner, but it was too big. Then I used a 6-inch wrench and managed to open it slightly to increase the water pressure, though it wasn’t an easy task. Ideally, I’d prefer a hand valve (like a knob), but I’m not sure if one can be fitted.

 

[Cal10]

That model should have a handle on that valve, most likely it has just fallen off or was lost by the installer. Part number 0020241700.