Hotel venues of all types contain many plug-in refrigeration and freezer units (“coolers”). Examples include plug-in refrigerators and freezers in kitchen/foodservice areas, vending machines, ice machines, beverage merchandisers, and the like. These appliances contain a condenser coil unit that is responsible for rejecting to the atmosphere the heat that is extracted from the enclosure being cooled. To do this job effectively, these coils need to have good airflow so that good heat transfer is achieved. Unfortunately, since the coils are exposed to the atmosphere, they become progressively clogged with dust and other debris over time (see photo at right below). Dead human skin cells that we all constantly shed is only one contaminant that they see. Unless frequently cleaned—experts recommend quarterly cleanings as a minimum target—the airflow through the coils can become largely compromised after only a matter of a few months. A 95 percent airflow reduction in a year’s time may be the norm.
So what happens when condenser coils become clogged?
Since the cooler’s performance is compromised, the unit will have to work harder to achieve its intended cooling. The compressor responsible for pumping the refrigerant through the unit will cycle on and off much more frequently than one that is in a unit with clean condenser coils. The data on this is quite thin but it appears that a unit with dirty coils might consume up to about 100 percent more electric than a cooler with clean coils. (Stated differently, you might cut the electric bill in running your coolers by about 50 percent if you keep the condenser coils clean). At an electric rate of only $0.11/KwH, additional yearly costs ranging from about $220 to $625 for each non-cleaned unit have been demonstrated. Multiply an average savings value of, say, $400 for each unit that you have not cleaned within the last three to four months. This will give you a rough idea of how much money you may be wasting by not having a preventive maintenance program that includes condenser coil cleaning. It can easily run into the several thousands of dollars per hospitality building.
The Importance of Quarterly Coil Cleanings
Refrigeration experts are in agreement that dirty condenser coils are a major reason for emergency service calls caused by a non-cleaned unit having to work harder than its design intended. The malfunctioning unit may also fail to hold its intended target temperature putting valuable cooled inventory at serious risk. The results are not good: a major repair bill (or unit replacement in extreme cases) and/or compromise of the cooled inventory in the unit. However, with quarterly coil cleanings both of these negatives can be largely ignored according to the experts.
So what is the industry doing with regard to this maintenance task? Unlike some activity that’s being directed to the coil cleaning of air-conditioning units, we think that the hospitality industry is largely “asleep at the switch” with the analogous maintenance task for the coolers in their buildings. We have seen this same disconnect in other industry sectors as well. Scant attention is being paid at present by most refrigeration unit owners to the big payback possible for keeping refrigeration/freezer condenser coils clean during their service life. One thing to keep in mind about the energy efficiency component of doing this job: every $1 in saved energy (which directly impacts the bottom line) is equivalent to from about $20 to $60 in added revenue coming in the door, depending on your overall profit margin.
If you are going to frequently clean the condenser coils in your cooler units (either yourself or by using a service provider), it obviously needs be done both effectively and quickly. Surface brushing and vacuuming of the coils is quick but is largely ineffective at getting at deeply embedded dust/debris that has penetrated into the interior of the coil structure. Coil cleaning brushes are available to get at the embedded debris but the additional use of these brushes will dramatically lengthen the job to an unacceptable extent (perhaps up to 30 minutes or more for each unit). Professional refrigeration technicians, when faced with the need to clean a clogged condenser coil unit, generally on an emergency service call, will usually resort to employing a blast of compressed air to dislodge all of the dust/debris.
The Use of Compressed Air
Compressed air cleaning is really the quickest and most effective way to get the job done. However, for any units located indoors, it is essential to catch the debris being blown out from the coils or the surrounding area will become contaminated. Until only recently, a damp fabric was the item used to catch such debris. The technician would drape the damp fabric over one end of the coil structure and direct the compressed air through the coils in the direction of the fabric. “Old school” techs might accept this approach but, if multiple units are to be cleaned under a preventive maintenance protocol, it has the drawback of requiring disposal/cleaning of that fabric after perhaps only one or two units are cleaned. Then too, if the fabric flies off during the cleaning operation, the technician has a cleaning task to perform in the surrounding area.
Fortunately, there have been advances in dust containment technology only recently that make the task a much more straightforward operation by eliminating the need for a “wet fabric” capture of the debris. By encasing the dusty coils in a dust containment hood of the type shown in the photo at right, the cleaning can be done much more efficiently. The hood has one port for the entry of compressed air (from a compressed gas cylinder or the exhaust port of a standard wet/dry vacuum). The second port in the hood allows for the entry of a hose from the suction port of a vacuum. The dual action of the compressed air and vacuum removes dust and debris from the coils, keeping them within the bag during the cleaning operation, until the debris is removed into the vacuum’s collection bag or chamber. “Voila”! Before you know it you are operating your coolers much more efficiently—at least until the next time that a cleaning is scheduled.
Richard P. Fennelly is Director of Product Development of CoilPod LLC, a manufacturer of dust containment devices for refrigeration coil cleaning using compressed air and vacuum. Contact for more information: firstname.lastname@example.org.