connect a boiler to hot water cylinder?

You need 'female straight or elbow fittings' - depending on your installation. The coil outlets are male, one inch, and these female connectors screw onto them, and the outlets will be 28mm. So, the connectors you need will be 28 x 1". Buy what you need - the supplier will always take them back. Use PTFE tape always, together with some thread sealant. You don't want any leaks from there.....!

John
April 2008