need help/advice, want to use existing indoor oil furnace as back up for outdoor wood unit taylor 750.outdoor unit is installed with circulator inside 3ft.from oil unit and feeding through water to water plate exchanger on return line,right now this pump is running 24/7 when turned on.i did it this way just to keep water moving from outside,water temp. from outside is controlled by aquastat on stove set at 160-180 .indoor unit has 2 zones controlled by Honeywell valves and thermostats and taco pump.MAIN QUESTION how can I hook up indoor unit and use everything such as zone valves and circlulator pump BUT not have burner fire unless outside water temp, drops,can I just install snapdisk control from outdoor unit pump to indoor burner controls ,would indoor vales and circulator still work controlled by thermostats,or would I need to do more than snapdisk? if snapdisk would work what temp. range and type would I need?open or close on rise thank you!