The Challenge of Coil Maintenance

Healthy buildings rely in part on clean coils throughout distribution systems.

• By Pieter van der Have
• 12/01/13

Truth or Consequences: All maintenance organizations do an effective job cleaning and maintaining all the coils in their air distribution systems. They all know what kinds of coils they have and where they are located. Reality check: Not all FM organizations are highly successful in this effort.

What are the kinds of coils that we might have in our inventory? That (somewhat duplicative) list might include coils such as fan, evaporator, heating, hot water, steam, electric duct, chilled water, DX refrigerant, refrigerator/freezer, cased and so on.

Associated with all these coils is equipment that interacts with coils and what they do, such as pumps, fans, compressors, filters and filter banks, control systems, drainage systems and more.

Why It Matters

An example of a generic coil drainage system would include a chilled water coil installed over a drain pan, which in turn empties into a drain. As long as the coil is clean, the water that condenses on the coil will also remain relatively clean. This results in a drain pan that remains clean longer, allowing continuous drainage of the wastewater. What happens if the coil and the pan are not cleaned to an acceptable level? Simple: the pan overflows, at the likely risk of damaging property or assets in spaces below. My experience suggests two irrefutable truths: more often than not, equipment such as this is installed above areas where critical activities occur and/or where essential documents are stored, and that Murphy was an optimist. Something will go wrong, unless proper precautions are taken through effective maintenance programs.

Cleaning of coils is one of those essential functions (perhaps as preventive maintenance) that seems to be neglected more than it should. It is a rather tedious, dirty job. Coils may be relatively inaccessible. Even more challenging is the reality that the cleaning function, depending on the coils’ geographical location and relationship to other types of activities, may need to happen as frequently as every month to only once per year.

How is it that some coils can get so disgustingly dirty? The answer is easy. All it takes is one or more of the following conditions to exist: No filter in the airflow, a dirty filter, or a lack of or inadequate coil cleaning programs or maintenance activities.

Tackling the Work

Once a coil gets dirty (plugged) to the extreme, options are limited, yet expensive. It may involve removal of the coil and taking it off-site to clean it with water pressure and/or chemicals. This will involve disconnecting plumbing, controls, etc., and may even require creative thinking to get it out of the building.

To save money, in-house staff may try to clean it in place, at the risk of doing the work improperly and bending the thin, aluminum blades that make up the surface of a coil.

If the weapon of choice is air or water pressure, we force the debris further into coil, essentially turning it into a solid concretelike slab. (Like cleaning your ears with a cotton swab.) Improper use of commercially available chemicals or use of the wrong chemicals can create additional problems, including further damage to the coil. At this stage, the only choice left is to replace the coil. This is not a happy choice, since the implementation of such a solution will be both expensive and time consuming.

There are valid reasons, other than the one illustrated by the preceding discussion, for ensuring proper maintenance of all coils.

1. Eliminate unsightly dirty ceilings around grilles and registers.
2. Eliminate mold odors, mold or bacteria in the airstream, which could affect occupants’ health.
3. Decrease the number of complaints of allergies.
4. Maintain desired airflow and A/C efficiency.
5. Avoid reducing life spans of equipment, and eliminating additional strain on compressors, fans, and related equipment, avoiding additional operational or capital costs.
6. Avoid negative impact on utility bills.

Coils generally rely on airflow in order to perform their expected function. If a coil must rely on a filter (not all coils do), that filter must be in better-than-okay condition in order to be effective. An example with which we can all identify is the filter under the hood of a car — the one that filters the air going to the engine’s fuel combustion system. Dirty air, no air or no air filter will affect negatively the performance of an engine. The same is true with a building’s air delivery systems.

We must avoid complacency and believing that everything possible is being done to assure proper functioning. Well-thought-out application of a computer-aided facilities management system will help monitor coil-related O&M and avoid issues generated by poor or lacking maintenance activities.

This article originally appeared in the College Planning & Management December 2013 issue of Spaces4Learning.