The completely automatic Digital FUEL WATCHMAN keeps an unfailing weather watch on your fuel consumption around the clock! It is super-sensitive to even the slightest change in weather and relays this change immediately to your heating system. Tried and tested for over 60 years under varying conditions, in both horizontal and verticalbuilding layouts, the Digital FUEL WATCHMAN is the ultimate in outside heat controls!
A properly engineered control system should enable you to save on fuel and maintenance costs, while giving greater heating efficiency.
http://www.fuelwatchman.com/products/digital-fuel-watchman/