The HVAC Factor: Executive View of Preventive Maintenance

By Lynn Burkhart
From the November/December 2015 Issue

Preventive-MaintenanceDecisions regarding finances are one of the most vital responsibilities of building owners and managers. Few areas impact expenditures more than HVAC sustainability and operational costs. While HVAC preventive maintenance (PM) programs abound, the pertinent information that impacts the facility’s budget often does not make it to the facility executives.

PM programs can provide facility executives with vital financial information as well as assist in maintaining valuable equipment. PM checklists at the engineer or maintenance level may include as many as 100 items. These can roll up into the overall efficiency, cost, and longevity of equipment.

At the facility executive level, details in the maintenance checklist may or may not provide a good picture. A summary of how PM impacts a facility is usually more helpful to a facility executive when making decisions affecting budget, manpower, occupant comfort, and sustainability.

Seven important issues a facility executive should look for in an HVAC PM summary are:

Check: Routine overall assessment of the air handlers has been done.
Purpose: Replacement costs can be budgeted.

A PM program should provide for an overall assessment of the air handlers so that management is kept informed of when replacement of the units will be needed. A report on the interior corrosion of air handler surfaces is a vital part of this assessment. Corrosion of surfaces such as condensate water collection pans, cooling coil supports, and sidewalls are the main reason for equipment failure and expensive replacement.

The assessment can also help facility executives manage efforts to prevent future corrosion. Maintenance personnel frequently fail to rinse aggressive coil cleaners fully from the coils and condensate pans they use to clean the system. This is the primary preventable reason for interior corrosion of condensate collection pans and cooling coil supports.

Costs for air handlers range from $50,000 to more than $150,000 per unit, and budgeting for their removal and replacement is often not projected in the budget. An unexpected and unbudgeted air handler breakdown can wreak havoc on annual budget accountability.

Air handlers have varying lifetimes, but units over 15 to 20 years old will likely need to be replaced in the near future. PM schedules should call for an interior photo of each air handler annually so the extent of the corrosion can be reviewed by managers.

Fouled HVAC cooling coil (Controlled Release Technologies)

Check: Coils have been cleaned.
Purpose: Save as much as 40% on energy costs.

With close to 50% of a facility’s electrical bills often spent on the HVAC system, HVAC operation expenses are another major concern of any facility executive. These operating costs increase considerably when cooling coils are dirty or fouled with microbial growth—each of which insulates the coil surfaces so they do not cool the air effectively. This causes the air handler to take longer to reach and maintain cooler temperatures. Thus the units run longer and consume more energy.

Dirt also plugs and reduces the flow of air through the coils, causing fans to use more energy to overcome restrictions in the coils. All of this increases operational costs.

ASHRAE, the association that provides standards for HVAC systems, conducted a formal engineering test and published that air handlers with dirty coils required as much as a 40% increase in energy to operate. This study was done on units that were cleaned just one year before testing.

Due to the amount of monthly savings, semi-annual coil cleaning can be cost justified. To reduce the costs of manual coil cleaning, a coating can be applied to the coils to reduce dirt and microbial buildup for a year or more. Annual photos of the equipment interiors should include the cooling coil condition.

Check: Air filters have been fitted properly.
Purpose: Reduce mold, fungus, and dirt buildup in the air handler and building airstream and increase system efficiency.

Another important area sometimes overlooked in PM schedules is the air filter enclosure rack and positioning of filters. Rusted filter racks leave gaps around the air filters, and air preferentially moves through gaps rather than through the filter itself. The result is that non-filtered dirty air gets caught in the cooling coils, reducing efficiency. The gaps around the filters also allow microbial particles, such as mold and fungal spores, to enter the airstream and get to the coils.

Microbial particles will cling to interior surfaces to form biofilms—which are up to five times more insulative than scale. To reduce biofilms and address the odors caused by microbes, an EPA registered sanitizer should be used on the system quarterly during normal filter maintenance. Sanitizing most coils should not take more than 10 minutes.

Check: Condensate drip pans are clean and free of standing water.
Purpose: Prevent odors and property water damage from overflows.

Microbial growth inside the air handler condensate drip pan is responsible for odors, and can also accumulate dirt that clogs condensate drains. When the drain clogs, water overflows, and in some cases it flows under the unit to the floor below. A timed-released EPA registered antimicrobial should be used semiannually to eliminate dirt buildup and microbial issues.

HVAC unit corrosion (Controlled Release Technologies)

Check: Condensate drip pans, sidewalls, and other interior parts of the air handler have been coated.
Purpose: Prevent corrosion and costly replacement.

Visual corrosion signals the impending demise of the unit. Corrosion can be seen in annual photos and does not require an expert to decipher. Handling corrosion early on prevents irreplaceable metal loss. Coating condensate drip pans, sidewalls, and other interior air handler parts prevents future corrosion and is the recommended solution to avoid premature removal and replacement. Corrosion resistant coatings should pass state and local fire codes as indicated by the NFPA, and be engineered for the harsh environment inside an HVAC system.

Check: Access door enclosures are tightened and leaks repaired.
Purpose: Resolve otherwise unexplained increased energy consumption by not allowing cold air to escape unused.

Unexplained increased energy consumption can occur from air leaks around air handler access doors and ductwork. A report indicating that air leaks have been looked for and addressed provides peace of mind when pursuing lower operational costs.

Check: Humidity readings have been taken.
Purpose: Double check how well the air handler is being maintained.

Relative humidity readings are another important factor in PM. Coils that are insulated by dirt and biofilms might not reduce humidity to required levels. The result is that high humidity levels in excess of 50% are very likely to contribute to mold growth and resulting orders. Once established, mold growth can be difficult to deal with, especially if it grows within the air ducts that are not easily accessible.

This checklist provides an overview needed to manage issues that affect the efficiency and sustainability of a facility HVAC system. Full sections of PM maintenance checklists can be attributed to these points, making it easier for a facility executive to find the cause and resolution of any problem areas that become apparent from the assessment.

Preventive-MaintenanceLynn Burkhart is the president and founder of Controlled Release Technologies (CRT), a manufacturer of HVAC maintenance products since 1985. The CRT Research and Development laboratory creates technologically advanced solutions for low-cost and effective HVAC maintenance.

Do you have a comment or a question? Please use the Comments section below.


  1. Coil cleaning is a much “overlooked” component that is raised here, with proven energy savings. However, most coil cleaning is conducted with:

    (a) cleaning agents that are corrosive in nature, (such as the Instant Powder Keg product the author’s firm makes, which has Sodium Hydroxide as its base and that constituent has a pH of approx 13) and so can be dangerous to apply, have the potential to damage the coil, and don’t rid the coil of biofilm; and
    (b) are not applied with a process that truly moves the crud out of the system – using hoses or small high pressure systems offers only short term benefits.

    For coil cleaning to be truly effective, with lasting benefits, the biofilm needs to be removed, and corrosive agents don’t accomplish that.

    The use of probiotic coil cleaning agents with alternating applications of Super Heated Pressurized Water (SHPW) offers a powerful, well documented and field proven coil cleaning process, and is a Best Practice after 3 yrs of field trials for a major global property management firm that achieves performance through engineering excellence.

    Probiotic coil cleaning agents are pH neutral and so safe to apply, won’t harm the coils and uniquely address the issue of biofilm, which is the greatest impediment to the thermal transfer efficiency of a coil.

    When combined with alternating applications of Super Heated Pressurized Water coil performance is well restored.

    The use of corrosive coil cleaners and simple, largely inadequate “water washing” processes represent an old technological approach, especially with the strong emergence of Aluminium Micro Channel systems, where use of corrosive cleaning agents voids the warranty. The “next generation approach to coil cleaning is use of Probiotic, pH neutral cleaning agents and processes that incorporate SHPW.

Comments are closed.