Mid position valve make should make no difference.
Don't think changing the boiler flow temperature should have any effect on the pump operation.
Pump should be constantly running with HW only selected as long as the cylinder stat is requesting heat.
Let us know how you get on.
Don't think changing the boiler flow temperature should have any effect on the pump operation.
Pump should be constantly running with HW only selected as long as the cylinder stat is requesting heat.
Let us know how you get on.