Coolant Header Tank Empty when engine cold?

[Parnz62]

Is it normal for my coolant header tank to be empty when the engine is cold, and then fill up once the engine is started and heats up?

Apologies if it's a silly question, but I am new to all this....

 

Also, I have noticed that my Webasto header tank bubbles a lot, is that normal or is there air in the system?

[Tracy D'arth]

Water expands as it is heated hence the level will rise. BUT there should be a bit of water in it when cold.

 

Bubbles in the central heating expansion tank would suggest that there is a poor connection on the suction side of the pump/heater that is drawing in air. Get it fixed else your radiators will rust away PDQ.