Is the water isolation valve/stopcock on?
Is there water pressure at the boiler end o fthe supply pipe?
The installation manual and the user manual are here:
Installation manual:
http://cdn0.vokera.co.uk/wp-content/uploads/2009/04/linea_installation_and_servicing_instructions.pdf - see section 5.3 and look at the drawings as well.
User manual:
http://cdn0.vokera.co.uk/wp-content/uploads/2009/04/linea_users_instructions.pdf
Thrudgit Stephenson, January 2015