The indoor Out door reset thermostat more or less works like the following.
For every TWO degrees it drops out doors it raises the water temperature 1 degree indoors.
It has very little to do with the actual circulator per say.
My ideal system is a circulator running on constant and letting non electric zone valves fine tune the indoor temperature.
You may like to take a short heating course offered buy Weil McLain H. E. A. T.
Heat education and training.
Or contact This company and then Contact me as I have a fantastic Master Plumber on Long Island who can help you out. Sylvan