Tech Tips

Testo 557 vacuum gauge and Appion core removal tools shown I've had a change of heart. Back in the early 2000s, during the big construction boom, I did many system startups on residential units for a large company I worked for. When installers ran the line sets prior to startup, they weren't always very careful […]

We already know that oxy-acetylene torches have a lot of safety considerations attached: don’t oil regulator threads, bubble-test your hoses, you get the picture. But there’s one more we haven’t really covered: the 1/7 rule (or 1/10 rule, based on the latest industry guidance).  This commonly cited rule reduces the likelihood of flammable acetone coming […]

When sealing ductwork or repairing HVAC insulation, the tape you choose dictates the long-term integrity of the system. Temperatures fluctuate wildly in attics and mechanical rooms,  and the tape must be able to withstand these environments without degrading. To better understand how different professional-grade adhesives actually perform under elevated temperatures, we decided to put them […]

Oxy-acetylene torch tip manufacturers publish charts that tell us the ideal applications for each tip size, which is quite useful on its own. After all, a small tip may be great for a ⅜” liquid line but would hardly make a dent in 2” commercial refrigeration piping. But we can also take the information from […]

In order to wrap my head around diagnostic issues, it helps me engage in thought experiments where I think of more extreme examples of an issue or situation or consider the ideal to find the “edges” of a concept. Once I find the extreme edges, I can begin to sort down to a more exact […]

We’ve all probably been in this situation before (maybe in both people’s shoes at different points of our careers): A technician is on the job with their apprentice. The technician tells the apprentice where the probes go on the service ports and exactly what the superheat and subcooling are.  The apprentice’s eyes glaze over, and […]

Even if you're not a market refrigeration tech, we all know that the primary function of refrigeration is to keep food cool. Easy, right? Even though food storage sounds pretty simple, there are a lot of things we should keep in mind when we think about food safety and quality. There’s a lot more to […]

The summer is a season of opportunity for HVAC technicians, and by opportunity, I mean a super high volume of service calls with a greater chance of callbacks.  We’re based in Florida, so our techs have to deal with the combination of blistering heat and higher humidity. That combo can cause all sorts of problems: […]

In a series circuit (loads connected in a row end to end), it's easy to calculate total circuit resistance because you simply add up all the resistances to get the total. In a parallel circuit, the voltage is the same across all the loads; the amperage is simply added up, but the resistance is a […]