The HLW1 Thermostat is primarily designed for use as a O/A wall mount high limit fresh air thermostat, typically used to break a 0-10v dc Y economy cycle signal controlling the position of damper motors. Or to override the position of 2 position damper motors. The output relay is voltage free permitting use on either 240, 24 AC circuits or DC control signal circuitry. Switch point is adjustable with it's status displayed via red / green LED indicators. The HLW1 thermostat is ideally suited for outside wall mounting perferably on a south facing wall or a location not exposed to the sun or other heat sources.