Got the Condenser Coil Blues?

Although there are a myriad of reasons why A/C and refrigeration systems have problems, many of them can be traced back to the “condenser coil”. An inefficient coil can cause reduced space temperatures and adverse system pressures that often lead to major component problems, including compressor failures.

 

The title of this article comes from one of our oldest and best representatives, Marty Sternberg. Marty personally evaluates many client job sites each year. I vividly remember visiting a site with him and his customer a few years ago. We were surveying a condenser coil that was obviously dirt laden when he suddenly pulled out a harmonica and started singing and playing a song he had made up titled, “You have the Condenser Coil Blues”. Fortunately, we all laughed, including the customer.

 

However, we all know that unit system problems created by condenser coils are not a laughing matter.

 

What condenser coil factors lead to these system problems? First take into consideration that condenser coil sizing as a component in a package or system is not oversized. In fact, over the last 15 years, the capacity of newer units are marginal at best. Even with a new unit, a customer doesn’t always get the rated capacity for the given operating conditions. Think gas mileage on the sticker of your new car purchase.  How many cars achieve the stated miles per gallon?

 

Consider the following. Condenser coils are the only coils installed in the HVAC system where there is no filter on the side where the air enters. The coil is also normally mounted outside, and many installations have environmental issues in and around their properties. Add to that the typical design of a condenser coil is now 16 fins per inch minimum and many are as high as 22 fins per inch. Why? The secondary surface of a condenser coil provides much needed heat transfer and manufacturers today significantly increase the fin count per inch.

Now look at the design of the condenser fans on a typical system. Airflow is very important to the coils ability to meet its capacity. There is almost no margin for error.  Because of the sizing of the fans and the motors, even a clean system may not produce the cfm airflow required. The improper mounting of fans can also cause air stratification across the coils, which is caused by the coil not receiving airflow across the entire effective face of the coil.

These are most of the conditions that lead to condenser coil problems. We have a very marginal system package that includes reduced coil area, improper fan and motor selection, and a coil with 22 fins per inch with no filter. Without proper cleaning and maintenance, after a couple of seasons, the results could be devastating. Even with diligence in the servicing of condenser coils, there can still be problems. This is the unfortunate news about coil condenser problems, but “forearmed is forewarned” – unless you want to learn the words to Marty’s song – “You Have the Coil Condenser Blues”.