Viessmann 100 boiler - no pressure

[CazStewart]

After working perfectly all day, we've suddenly lost pressure in the boiler, which is now showing zero, so the boiler has shut itself off.

We've look for a stainless steel pipe to refill the system, but cannot find one at all underneath the boiler itself.

There appears to be a yellow tap, which I assume is the gas outlet and two smaller black taps connected to a small copper pipe "loop", which could be what I need to turn. However, only one of these black taps turns. The other refuses to budge and I don't want to force it.

Any ideas please?

 

[ianmcd]

the yellow tap is definately the gas so dont touch that , not sure about the other two you refer to , could you post a photo of these and we may be able to advise you better ?

 

[CazStewart]

Hi Ian
Thanks for your reply. We decided to try the stiff black tap again and success! It turned open and we were able to pressurise the boiler, which soon had the radiators hot again.

 

[xr4x4]

Did it suddenly lose a lot of pressure, or was it low and just dropped to low for the boiler and cut out?

You also need to check the system pressure while the system is running and hot.