Back in the “good old days,” controls were all analog and mechanical; that simply means they acted in a directly connected and variable manner based on a change in force. Both pneumatic (air pressure) and hydraulic (fluid pressure) systems are examples of mechanical or analog controls. When the pressure increases or decreases on a particular […]

DISCLAIMER: HVAC School is NOT an official OSHA safety training resource! Although we provide safety tips in good faith, our website is not a substitute for safety training from an authorized OSHA training source.   Let’s be honest: most of us probably got into the HVAC trade because we enjoy working with our hands. Unfortunately, […]

We've been getting many questions on micron gauges that are ”going haywire” or reading in the micron range, even at atmospheric pressure. First, micron gauges measure absolute pressure, so you can’t ”zero” them out. They use tiny, very sensitive sensors that are calibrated to air, not refrigerant, so anytime refrigerant gets into the gauge, it's […]