On an energized, intact circuit, you will read voltage across an OPEN switch, not across a CLOSED switch, when testing with a voltmeter. 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 your voltmeter. I have seen many […]

Suction pressure, head pressure, subcooling, superheat, delta T. Taking all five of these calculations into account on every service call is critical. Even if you must do further diagnostic tests to pinpoint the problem, these five factors are the groundwork before more effective diagnostics can be done. I would also add static pressure as an […]

This article was written by HVAC contractor and Building Science Whiz, Michael Housh. Thanks, Michael! For a while, I’ve fallen into this camp where I feel Manual J overshoots heating loads. First off, I would like to say that Manual J is only as good as the information you give it, but we often run […]