This Direct Acting (DA) control operates on a single pole single throw (SPST) snap-action mechanism

Standard 24V AC coil compatible with most low-voltage HVAC control boards and transformers

It uses SPDT switches to shut down the burner and trigger an alarm or secondary device if the water level reaches a critical low point

Enhanced System Safety: Includes a manual reset function for critical low-water conditions

and multi-stage gas valve regulation

Resideo TH140-28-01-B Programmable Thermostat 318172-701 This Direct Acting (DA) controlThe Resideo TH140 28 01 B Programmable Thermostat is a versatile 7 day programmable digital thermostat designed for high precision control in hydronic, line voltage, and low voltage heating environments. Engineered to handle everything from millivolt systems to 240 Vac heating applications, this unit is a staple for technicians installing electric baseboard heaters, as well as gas or oil fired boilers. With a single pole double throw (SPDT) switching