Air changes per hour (ACH/ACPH) simply describes how many times the 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 is supplying a balanced 100 CFM (cubic feet per […]

When we say that there is “flash gas” at a particular point in the system, it can either be a bad thing or a good thing, depending on where it is occurring. Flash gas is just another term for boiling. It is perfectly normal (and required) that refrigerant “flashes” or begins boiling directly after the […]

On an energized, intact circuit, you will read voltage across an OPEN switch when testing with a voltmeter. However, you probably won't read significant voltage across a CLOSED switch. Both sides of a closed switch are electrically identical (or at least very close). Therefore, there should be no movement of electrons between the leads of […]