Manual here:
http://cdn0.vokera.co.uk/wp-content/uploads/2011/09/mynute-12-16-20e-installation-and-servicing-manual-copy.pdf
INfo on ignition sequences here:
http://www.gasboilerforums.com/manuals/vokera/Boiler%20Ignition%20and%20sequence%20of%20operation.pdf
For more expert advice try a dedicated plumbing forum, for instance:
http://www.ukplumbersforums.co.uk/central-heating-forum/
Me/here
February 2015