More Extremists In The Uk Than The...
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No best answer has yet been selected by householder. Once a best answer has been selected, it will be shown here.
For more on marking an answer as the "Best Answer", please visit our FAQ.I think antiguru is spot on. You should be able to identify what each control does by switching each one up in turn in the middle of the day. The control that gives you instant heat output is an output control.
I would expect the output control to drive a small fan. If you turn it up, this drives more air over the hot bricks in order to speed up the removal of the heat which was added overnight. Alternatively, it may control a vent which increases or decreases air flow over the bricks due to natural convection. To keep the place cool overnight, the output control should be set to minimum.
There is a brief description in wikepedia: