On Wed, 06 Aug 2008 20:08:28 GMT, Stephen
wrote:

Grant Vortex boilers - I had never heard
of them - but the literature says they have Riello burners

Sorry to add to my own post but I have found the Worcester Bosch
Greenstar Camray also has Reillo burners. From the various
manufacturers' web sites I have not learned much. They also seem to
sell white boxes with four 22mm connections. How do I choose between
them? Just look for the cheapest or the one with the highest
efficiency percentage?

Am I right to think I should not "upgrade" to a higher powered boiler?
Would this be inefficient because it would lead to cycling?

Thanks,
Stephen.