The plan now is to disconnect the oil fired aga and fit a higher output
wood (multi fuel) burner as a replacement to heat water and rads. There
is already a heat dump rad permanently across flow and return with three
zone values controlling circuits to DHW cylinder coil, bathroom towel
rails, all other rads.
The programmer would be redundant as the firing up of the burner is
entirely manual but should the zone valves be retained with some simple
manual switching maybe using the cylinder stat to give hot water
priority or would it be simpler to remove those also.

Martin