More HVAC Help from our Expert...Gary Xavier. Coil Cleaning Procedures to Keep Your Facility Air Conditioning in Form

Trained building maintenance personnel can easily create a preventive maintenance procedure for the coils on each unit in the facility. Every coil should be monitored on a regular basis, and a cleaning frequency determined and added to the scheduled preventive maintenance tasks.

Cleaning of evaporator coils must be performed while keeping in mind that anything on the coil can enter the building air stream. Care must be taken to use only products that are specifically labeled for evaporator and/or chilled water coil cleaning. The use of general, multi-purpose cleaners may result in residue on the coil that attracts dirt, as well as contamination of the building air stream with hazardous, or simply annoying, fumes. Air conditioning and refrigeration suppliers typically carry a complete selection of coil cleaning products, and should be consulted for recommendations. And, there is a lot of information here.

Evaporator coils can often be cleaned by shutting off the fan and simply spraying the coil with the selected cleaning solution. Most evaporator coil cleaning products are designed to be rinsed off by the condensate formed during the unit’s operation, thus requiring no rinsing by the technician. While the unit is shut down, the filter should be cleaned or changed, and the condensate drain pan and drain inspected and cleaned if necessary.

For condenser coils, the cleaning solution chosen should be matched to the contaminants on the coil. Cleaning compounds are available in both acid and base formulations, serving different purposes. Acidic (low pH) products are generally recommended only if corrosion deposits need to be removed; while basic (high pH) cleaners are used for removing grease and most types of fouling.

Regardless of the cleaner chosen, strict adherence to the labeled directions is critical, including following the recommended dilution guidelines. Maintenance personnel must also be aware of the hazards of handling and use of all chemical products, and follow the manufacturer’s guidelines for protective equipment. Consult the product Material Safety Data Sheet (MSDS) before use.

Condenser coils should be cool before the cleaning procedure is started. Using the proper cleaning compound, soak the coil with solution while making sure that the cleaner penetrates the entire depth of the coil. After allowing time for the solution to loosen the soil, rinse the coil with water, rinsing from the back to the front if possible.

High pressure water may be used as long as the water does not bend the fins on the coil or is aimed directly on motors and electrical connections. If necessary, the motor can be covered with plastic prior to cleaning.

Once the cleaning solution has been completely rinsed away, a fin comb should be used to straighten any bent fins on the coil, and the unit returned to operation.