The simplest way to improve efficiency, rather than buy an expensive
sophisticated boiler. Then there is the matter of effective making your
cylinder bigger by adding some simple controls.

We're not discussing the simplest way of improving efficiency. We're
discussing the simplest method reheating a cylinder.

The methods being discussed have some advantages. Increased simplicity isn't
one of them, although it may not be sufficient disadvantage to preclude
their implementation.

Christian.