In this short podcast, Bryan answers a listener-submitted question about Nylog, oil, and where you put them when you're making flares.

Nylog is a thickened refrigerant oil (which is either POE for Nylog Blue or mineral oil for Nylog Red), and it's miscible with the refrigerant and moves with it through the circuit. You don't want to put excess Nylog on valves, but a small amount won't do harm. There are a lot of concerns about Nylog voiding the warranty, but it doesn't actually do that because it's nearly impossible to prove that Nylog caused the issue.

Like oil, Nylog helps connections fit together (even threaded connections) and prevents galling. However, oil and Nylog also reduce friction, which will affect your torque specs when you use a torque wrench to tighten a connection. You don't need to tighten it as much, as you risk overtightening otherwise.

When you apply Nylog, put a little bit on the front and back face of a flare (and the cone of the flaring block if you wish). You can put a small bead on the threads, but it's not an issue as long as you stay aware of your adjusted torque specs (low range). In our experience at Kalos Services, Nylog is particularly useful under vacuum and has helped us make high-quality flares that last a long time. Remember: Nylog is NOT leak lock, and it's not a traditional thread sealant.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.

Subscribe to our YouTube channel.

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android

In this short podcast episode, Bryan answers a listener-submitted question about oversized evaporator coils, particularly when they're half a ton or a full ton larger than the condenser.

The expanded performance data contains the information that'll tell you whether the coil is right for the system. However, when it comes to the specific issue of oversizing, there is a common misconception that coil size affects the saturated suction temperature. The truth is that they're not related; you could fully insulate different-sized coils and move the same amount of refrigerant, but they will behave similarly.

The saturated suction temperature (suction pressure, evap temperature) is driven by the heat entering the system. Coils are designed to handle refrigerant flow rates and airflows, so having a lower airflow over a large coil allows for greater cooling due to the bigger surface area, lower bypass factor, and dwell time. When more heat enters the evaporator coil, the saturated suction temperature increases, but some of that heat enters as latent heat and helps with dehumidification. However, a larger coil also takes longer to get colder, and the superheat settings become more important.

You have to be careful with lower face velocities across the evaporator coil, as laminar flow isn't as good at transferring heat as turbulent flow. That is one of the limitations of using a larger coil with lower airflow. If the expanded performance data has a rated match for a larger coil, then that same data will also contain information about the required airflow. Testing in and testing out is also important.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Subscribe to our podcast on your iPhone or Android.

Subscribe to our YouTube channel.

Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android