Whoops. Did I say boiler? I was thinking off the heatbank. In any case,
having a multiple subzoned system off the boiler is easier implemented
with
zone valves in an S-Plan-Plus configuration (swapping the boiler for the
heat bank as the heat source) than having, say, six takeoffs (each with
pump) from the heat bank to supply each zone.

P.S. It also requires less pipework in most cases, as a large bore unzoned
main can snake around the house and the zoned takeoffs taken where
convenient. Having the zoning done centrally can result in excessive
pipework requirements, although it would allow microbore for those who
prefer it.

Christian.