How Proper Maintenance Can Increase Reliability, Save Energy, and Reduce Your Occupancy Costs

Written by Rick Dassow. CEO - CMI Mechanical

In facility management, the reliability of your HVAC equipment is more than just an issue of tenant comfort. For many companies today, heating and air-conditioning can make or break a business and can be mission critical to a company’s ongoing economic success.

For example, restaurants, retail stores, hospitals, computer rooms, office buildings, clean rooms, and call centers are completely dependent upon the consistent heating and cooling of their facilities.

In these industries, heating and cooling issues are not just a matter of convenience. These issues can be the source of losses in revenue and productivity and even catastrophic equipment failure for the tenants or occupants of the building.  

Additionally, the energy costs associated with running the HVAC systems are a significant portion of the facility manager’s operating budget.

Indeed, an entire industry has sprung up around energy management, with a focus on reducing facility energy consumption. That is why it is so critically important that the progressive facility manager understand the basic principles of the refrigeration cycle, and develop a program for implementing a sound preventative maintenance program that focuses on both reliability and energy efficiency.

Unfortunately many HVAC preventative maintenance contracts are set up for infrequent filter and belt changes, along with visual inspections of the unit. While this is better than nothing and represents the basic elements of a preventive maintenance inspection, it is merely the tip of the iceberg.

To begin with, HVAC equipment is designed to operate at maximum efficiency and capacity only if maintained within a tight tolerance of operating conditions. Poorly maintained equipment will adversely affect the unit by reducing the efficiency of the unit and stress the system to such a degree that eventually the unit will cease to operate.

Even a unit that appears to be operating ok, it can be losing 25%-35% of its energy efficiency and capacity as a result of poor maintenance.

Let’s take an example - a 20-ton unit running 2,000 hours a year will consume an average of $4,218.00 in electricity each year if running at 100% efficiency. A twenty-five percent energy degradation for a single unit under these circumstances wastes approximately $1,054.50 in extra energy each year.

If a single building has 10 rooftop units we have lost $10,545.00 in energy consumption for the year. For a facility or property manager with multiple properties or a large portfolio, the dollar savings from efficiently running units can be significant.

Consequently, it is critical that the HVAC technician collect several key measurements and perform calculations that will determine if the unit is operating within its designed tolerance. Five important measurements include:

• Suction pressure
• Liquid pressure
• Suction temperature
• Liquid temperature
• Ambient temperature

From there, the technician can calculate superheat, subcooling, condensing temperature over ambient, condensing temperature drop, and evaporator temperature drop. Without getting into an in-depth discussion of refrigeration properties, suffice it to say these are key measurements that are the best predictors of how efficiently the unit is running.

Armed with these measurements, an experienced and well-trained technician can quickly determine if the unit is under or overcharged if the compressor is slugging, whether there is a restriction in the line, or if a test is required for contaminants in the refrigerant.

These measurements will also indicate whether the coils need cleaning, as well as a variety of other faults that may have occurred within the system. Clearly, this could not be accomplished by a visual inspection of the unit.

The old school of thought is that “if it isn’t broke, don’t fix it”. This idea disregards the enormous amount of energy loss resulting from a poorly balanced system and creates the conditions necessary for future failure of key components in the unit.

The most progressive HVAC companies understand the importance of this concept and generally use computerized diagnostic tools to collect and calculate these measurements during a preventive maintenance inspection. From there, adjustments are made during the inspection to bring the system within its designed operating tolerances and achieve maximum operating efficiency.

In today’s environment, the next step in preventative maintenance is to reduce energy consumption by ensuring that the units are operating at their maximum efficiency and capacity. This requires a complete diagnosis of the unit and the use of key measurements to determine if the unit is running efficiently. And finally, the resulting reliability gains also affect the very core of your tenant’s business and will ultimately determine the success of the individual facility manager.

About the Author

As CMI Mechanical's CEO, Rick Dassow is responsible for mechanical services throughout the entire United States. He brings a diverse background of facilities and real estate expertise and has an extensive background in running large divisions for national facility service organizations. Rick has an undergraduate degree from the University of Wisconsin Madison and a Masters in Business from DePaul University.