Tech Tips

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. […]

Does setting a thermostat too low cause an air conditioning system set in cool mode to freeze? The answer is no, at least not directly. However, low evaporator load (low return temperature or low airflow) and low outdoor ambient temperature can lead to evaporator coil freezing. Low indoor setpoint can lead to low return air […]

I didn't install this unit. First off, attic installations are among my least favorite applications from the standpoints of serviceability, system longevity, and a laundry list of other items. Here in Florida, it's just a bad idea due to the high humidity and temperature in a vented attic and the condensation issues that can and […]