boiler fault gloworm ultimate 40BF

[efficient]

just been called to a boiler fault hot water but no heating.. tested room stat thats fine tested.
its running of a FP715 programmer and a WB12 wiring centre. but there is no live connection to the boiler... but the boiler fires on hot water demand ???????? any ideas or am i missing something really obvious.

 

[tamz]

How many pipes come off the top of it?

 

[efficient]

4 - 2 gravity 1 flow 1 return

 

[tamz]

Check the pump.
There is no permanent live on these boilers, only a switch live

 

[gasmarc]

it could be the programmer that is not sending the signal but agree with tamz ,pump could be stuffed but boiler would still fire up and give no heating ,good luck