My central heating will not come on unless i have turned the hot water on as well, any ideas?

Netty, February 2007

I am guessing you have a separate programmer ie not integral to the boiler.... some programmers have an inbuilt switch to enable heating only to be selected, this option can only be used if you have pumped primary to hot water cylinder, and is normally associated with a 3 port diverter valve, or 2 port zone valves.

Pete, February 2007