Q: What is the difference between an MPS and a DTC120-G roof deicing controller? A: The MPS uses a combined aerial mounted ambient thermostat/moisture sensor and operates on a 75 minute timing sequence. The DTC120-G uses an ambient thermostat with up to four separate gutter mounted moisture sensors and it operates on a 35 minute timing sequence. The gutter sensors allow you to zone the deicing system. On some buildings in urban settings these are installed due to differing sun/shade patterns. Both controllers require a 120 volt input and can be wired to the Delta-Therm GFPE contactor panel. The GFPE contactor panel.