You may have noticed that 3/8″ liquid lines are generally the norm in equipment 5 tons and under. We went to a job where the system had a 1/2″ liquid line, and it got me thinking about the ramifications of going larger or smaller on the liquid line. Liquid Line Basics The liquid line should […]

In residential, most techs and installers size the suction (vapor) and liquid lines to the stubs on the equipment. In larger built-up systems, sizing the piping is rarely the responsibility of the technician. But what happens if we show up to a job where the lines cannot be (reasonably) replaced because the size is different? […]

Air changes per hour (ACH/ACPH) simply describes how many times the total quantity of air in a room (or structure) is completely replaced per hour. If you have a 10'x10'x10′ room, the room contains 1000 cubic feet of air. If the supply and return to the room provide a balanced 100 CFM (cubic feet per […]

Carter Stanfield, a co-author of Fundamentals of HVACR, talks about the entire refrigeration circuit. He also explains how to read and plot a pressure-enthalpy diagram. The refrigeration circuit has four main components: evaporator, compressor, condenser, and metering device. When teaching, Carter likes to explain that boiling is a cooling process and condensation is a heating […]