another question re: live feed from pump to boiler

[rhinosaw]

Currently old vented system , S plan , no pump overrun. pump in airing cupboard.
Moving to system or heat only boiler with separate pressure vessel and existing pump
question is: would I need a live feed from pump only if using heat only boiler?
with system boiler having pump built in I presume live feed not needed?

 

[muggles]

A system boiler will almost always need a 4 core supply - permanent live, neutral, earth, and switched live.

Heat-only boilers tend to vary. Some need a permanent Live, some don't. Some need the pump to be wired back to them to provide an overrun, some don't

 

[rhinosaw]

Thanks Muggles
At the moment if the timer turns HW or Heating off the pump also cuts off immediately.