It provides active flow modulation based on evaporator load

which is essential for modern HVACR modulation

as long as the negative pressure switch requirements fall within the 0

The Laars Heating Systems R2005600 is an essential diagnostic light set designed for high-output commercial boiler maintenance and performance monitoring

Resideo T812A1010 Thermostat 340155-7026 It provides active flow modulationEngineered for reliable, low voltage control of single stage heating systems, the Resideo T812A1010 Thermostat is a staple for service calls requiring a durable, non programmable heat only thermostat. This unit features a snap acting bimetal switch that eliminates the need for precise leveling during installation and avoids the use of mercury. Field tested for 24 Vac heating systems, it operates on a Single Pole Single Throw (SPST switching action)