reducing unburned gas accumulation and "hard starts

Its robust construction and standardized mounting make it a dependable choice for maintaining peak system performance during demanding heating cycles

The rugged construction resists diaphragm fatigue

This controller provides a seamless interface for Friedrich HVAC parts replacement

Siemens Building Technology QFM81.21 Hygrostat 320074-702 reducing unburned gas accumulation andThe Siemens Building Technology QFM81. 21 is a commercial grade duct hygrostat designed for precision relative humidity control in HVAC systems. Engineered for both monitoring and regulation, this device features a stabilized sensing strip that ensures superior linearity and long term stability, even in high humidity environments or air contaminated with dust. Unlike baseline models, the QFM81. 21 utilizes an internal setpoint adjuster to prevent