This is the closest discussion, I could find anywhere, that might help.
Would it be possible to plumb/wire some form of fully-pumped c-plan? Utilising the existing central heating pump. Or s-plan, with one pump?
Maybe with a lockshield to control pumped DHW return flow?
Existing set-up:
grundfos alpha 2l pump
potterton diplomat 55/68 boiler (yes, you read that right). 22mm pumped flow and return on CH. 22mm gravity flow and return on DHW.
C-plan
one way sprung valve, to prevent DHW gravity circulation to radiators.
heatmiser CH/DHW room stat
honeywell pipe stat, on DHW return
gledhill torrent 170l, mains hot water, open vented tank
Do I really need another pump, and zone valve to pump the DHW, in this set-up?