I wouldn't even bother checking valve end switches and whether or not they're wired in. Just wire the red wire in terminal 1 to the new timer connection 3 and the black in terminal 4 to 4 on the new timer. When you power the timer turn heating on by its self, if the boiler fires great, you're done, if it doesn't just take the timer back off and remove the little black jumper at the back of the timer, this will link the heating and hot water.
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