Hydronic Boiler Control, 24 Vac, Nema 1, Modulation Output: PWM, 4-20 mA, 0-10 Vdc, Flame Rod or High Energy Spark Sensor Type, Frost Protection, Slow Start, Anti Condensate, Boiler Delta T, Stack Limit, Boiler Limit, DHW Limit, Outlet T Rise Limit, Two Temperature Loops of Control