We've all heard some version of the phrase “heat rises,” but is that really true? First, we need to remember that heat is energy, not matter. Heat is a force, not a thing. So, while heat may result in changes to matter (stuff) it, isn't matter itself. When we add heat to stuff, the molecules […]

Compressibility is the ability of a substance to be squeezed into a smaller volume. It is the change in volume and increase in density that results from an increase in pressure. The subject of compression should be familiar to HVAC techs. After the return air passes over the boiling refrigerant in the evaporator coils, the […]

I don't do much in the way of “rack” refrigeration. However, I recently had a conversation with experienced rack refrigeration tech Jeremy Smith, and he got me thinking about EPR valves. I've heard EPR (evaporator pressure regulator) valves called suction regulators or hold back valves. In essence, they hold back against the suction line to […]