Tech Tips

I had an old-timer tell me that you can never connect two transformers together because they will “fight one another.” If you are anything like me (and heaven help you if you are), a cartoon in your head starts playing whenever someone says something like that. In this case, I imagine two transformers with boxing […]

Let's get something out of the way right off the top: saying that we learn best “hands-on” is sort of like saying we prefer to breathe air. WE ALL NEED TO APPLY THINGS TO LEARN THEM DEEPLY! David Sandler wrote the book You Can't Teach a Kid to Ride a Bike in a Seminar, and […]

As HVAC/R Technicians, we use tools and instruments to take measurements every day. In fact, 90% of our job could not be done efficiently without some kind of measurement.  “How do we measure?” “With what instruments?” “How accurate are these measurements?” These are all questions a thoughtful technician should ask before spending money on a […]

  Image Courtesy of Eaton SNAP ‘N SHIELD Piping support is covered in Section 305 of the IMC (International Mechanical Code). Once again, the IMC isn't binding, but it is what most local codes are based on. Piping / Tubing Material Maximum Horizontal Distance Between Support Maximum Vertical Distance Between Support Copper Tubing 1 1/4″ […]

We keep two-pole, 40-amp 24v coil contactors on all of our vans. They are versatile and reliable, and you can replace most residential A/C contactors with them. There are a few things to watch for, though, especially when you have a crankcase heater. Many brands power the crankcase heater constantly and shut it on and […]

We have discussed DTD (design temperature difference) quite a bit for air conditioning applications, but what about refrigeration? Let's start by defining our terms again. Suction Saturation Temperature The saturation temperature is the temperature at which the refrigerant will be at a given pressure if it is currently changing state. This change of state would […]

Most controls and thermostats will have some sort of cycle rate per hour setting that kicks in to prevent over-cycling once the setpoint is reached. These cycle settings don't kick in until the system starts achieving setpoint, so don't worry if it will shut off if it's set to 70° in heat mode and it's […]

When a system has abnormally high head pressure (high condensing temperature over ambient) and compression ratio, one of the easiest things to look for is a dirty condenser coil. More often than not, that will be the cause. However… There is another category of issues that can cause high condensing temperature (high head pressure), but these […]

I just noticed this portion of the Carrier air handler sticker for the first time the other day. I'm like most techs; it's easy for us to ignore the great info posted right in front of us on the data tag. That's because so many of the notices contain info we are used to seeing. […]