Different strategies have been used by facilities and property managers for managing the maintenance of HVAC equipment. The following are the three most prevalent approaches taken and their characteristics:
- Preventive/Time-based – timely repairs to avoid higher expenses later; moderate up-front costs
- Reactive/Deferred – deferring costs at the risk of incurring higher costs later; no up-front costs
- Predictive/Conditional – spending when and as needed; high up-front costs
Each of these approaches may be valid based on a company’s operational needs, budget situation, and the type of equipment installed in their facility.
This paper addresses the advantages and disadvantages of each approach as it pertains to an organization’s goals and the benefits they pursue – including the costs and consequences of their choices. It will also provide various aspects to consider when making an informed decision on a strategy and approach to maintaining HVAC equipment.
What is the Desired Result?
Numerous studies exist extolling the benefits of maintaining equipment. These include:
- Saving Energy and Emergency Service Costs
- Extending the Life of Equipment
- Improving Comfort and Minimizing Disruptions for Employees and Customers
The approach you take depends on the priorities and operational needs of your organization, employees, and/or tenants. It also depends on the equipment to be maintained and the financial constraints you operate under, including the approach taken by Finance personnel in expensing capital equipment.
Costs of Energy and Emergency Service
If the primary goal is reducing the costs for energy and reactive service calls, a rigorous Preventive and/or Predictive Maintenance program tailored to your equipment and needs is usually implemented. When 40-50% of your energy usage is consumed by heating and air conditioning equipment, simply keeping both the evaporator and condenser coils in your equipment clean and able to transfer heat can save up to 25% of those costs. Add to that the resulting premature repair costs from wear and tear on the equipment when it has to struggle to meet the demand to heat or cool the building.
If an emergency service call is required when a component fails – for example a compressor – the cost to replace it could be significantly higher than if it had been identified and the condition that threatened the compressor remediated during a routine maintenance visit.
Facilities and property managers intuitively know the longer equipment is operated that’s in need of repair, the more it will cost to ultimately fix it. But how much? David Tod Geaslin – an MRO expert and instructor at Texas A&M University – came to realize that a linear relationship was an inadequate metric for predicting “before” and “after” breakdown cost. Thus, he developed his “Inverse-Square Rule for Deferred Maintenance” axiom which states that deferring a needed repair may result in a cost of up to 15 times the cost of making the repair. An analogy that neatly illustrates this rule is changing the oil in your car – would you risk seizing the engine in your automobile by foregoing the cost of a simple oil change?
Reactive – also known as Deferred – Maintenance therefore results in higher energy costs and increases the costs of emergency service calls. In small facilities where the cost of energy is not large in absolute terms, the organization may not be able to cost-justify savings from efficient operation of equipment, nor worry excessively about the life of their HVAC equipment. Their customers may not visit the facility or there may only be a few employees in a small office; neither is a strong argument mitigating the impact of an interruption in heating or cooling. Also keep in mind most of these facilities are governed by triple-net leases where the occupant does not consider capital improvements as beneficial to their business.
In some facilities a condition-based service approach has been utilized – Predictive Maintenance. Information is collected from equipment and then analyzed, generating maintenance tasks only when they’re needed. Less money is spent on tasks that may not be required. Over time, the maintenance plan is developed based on actual operating conditions and not necessarily manufacturer or service provider recommendations. This approach is gaining traction in larger facilities with extensive budgets based on years of technical experience with massive heating and cooling plants. This approach is expensive, oftentimes requiring Building or Energy Management Systems that cost hundreds of thousands – if not millions of dollars – to implement.
Preventive Maintenance can provide many of the same results as Predictive Maintenance over time and with little additional cost. First, a cadence for changing filters, adjusting or replacing belts, and quick inspections of each section of a system – including the heating, cooling, and electrical compartments – can be easily developed by maintenance staff or, preferably, in consultation with your service provider if you outsource.
But more importantly, affordable, Predictive systems are now available for small- and medium-size facilities and businesses that doesn’t require a massive investment in infrastructure and technical expertise. One of them uses a proprietary algorithm and a few well-placed sensors to provide advance notice that a heating or cooling system is performing poorly and/or is about to fail. Its notifications are available via the Web to the customer and service provider, allowing a service call to be preemptively scheduled to avoid or minimize system downtime.
This allows facilities managers to continue to drive the costs of maintaining HVAC systems lower, combining the use of both Preventive and Predictive Maintenance.
Equipment Life Expectancy
There is no doubt that both Preventive and Predictive Maintenance can and will extend the life of HVAC equipment. With a Preventive Maintenance approach, it is incumbent upon facilities and property managers to work with their HVAC service provider to design a program that makes sense for each piece of equipment, foregoing unnecessary tasks for those that capture the majority of problems that can be expected to arise. This cost/benefit ratio can be instrumental in reigning in unnecessary spend on maintenance.
For example, packaged roof-top equipment and condensers act like large vacuum cleaners. The degree to which the equipment’s coils are exposed to and fouled by air-borne debris varies based upon the location of a facility. Does it make sense to chemically clean all the condenser coils at all locations on a semi-annual basis?
No one denies that keeping the coils clean will ensure HVAC equipment is operating optimally. But how they’re cleaned and when impacts the cost of the maintenance program you implement. Other examples of how the design of a Preventive Maintenance program impacts its cost:
- the frequency of filter changes (which also can affect air quality)
- recording refrigerant pressures despite the age of the equipment.
With Predictive Maintenance, cost is delayed because the program is inherently based on only what is needed. Each task costs what it should, but is only performed ad hoc; you ignore them at your own peril.
It would be counterproductive to spend much time discussing the life expectancy of equipment that is subject to Deferred Maintenance. With this approach, equipment is tended to only after it fails, with hardly any emphasis on avoiding long-term damage. The life expectancy will be significantly less than equipment that is maintained and serviced regularly.
Disruptions Due to Equipment Failure
The importance of reliably maintaining a set temperature in your facility varies by industry. A restaurant or other retail establishment places a much higher premium on reducing outages than a mixed-use facility that has 800 ft² of office space occupied by 4 employees 3,000 ft² of warehouse space with a few warehouse workers. (Air conditioning and refrigeration are rarely used in a warehouse environment unless the inventory requires it.) Deferred Maintenance might be an option for the mixed-use facility.
Office buildings are as likely as retail establishments to be sensitive to equipment failure. Ask any facility manager! Clearly, Preventive Maintenance or Predictive Maintenance are appropriate approaches in this scenario. However, due to the up-front cost of Predictive Maintenance, they will only be deployed in large, Class A office buildings and facilities where the cost of shutdown is prohibitive.
However, the future of Predictive Maintenance holds a lot of promise. Eventually it will have an extensive knowledge base with experience exceeding that of the most seasoned technician. Equipment manufacturers will start to provide the sensors and diagnostics that will make the information easily and inexpensively available. And it will come to a diagnostic conclusion with the speed of a computer, significantly outperforming its human counterpart. The result will be fewer high-margin jobs in the wake of a catastrophe, but more predictive, low-margin maintenance costs.
On the other hand, a Deferred Maintenance approach – while perhaps a viable strategy for warehouses – is not an alternative for serious property and facilities managers. By definition, system outages are the norm, not the exception, using a Deferred Maintenance program.
For the vast majority of facilities, Preventive Maintenance is still the most cost-effective method to ensure comfort and reduce costs. If properly designed, a Preventive Maintenance approach will be tailored to meet the needs of any facility.
A good starting point is contained in the Appendix. It has a generic list of tasks to be considered for any maintenance program. It is organized by the functional sections of HVAC equipment, so it can be applied to most standard equipment, including packaged RTUs, split systems, heat pumps, and fan coils.
Property and facilities managers have many choices when creating and implementing maintenance programs for HVAC equipment that meet a client’s budgetary requirements. It is incumbent upon facilities and property professionals to tailor those programs to the needs of its customers in different industries, with diverse building types and with varied equipment. They should consult with their service provider/HVAC contractor that will take the time to prepare a customized approach for their specific needs.
Appendix – Maintenance Checklist (General)
- Record make/model/serial/unit location and any other tag identifiers
- Check and adjust thermostat – confirm operation
- Record and confirm voltage to unit(s)
- Inspect ductwork
- Replace air filter – clean reusable-type
- Inspect all wiring and connections to controls and electrical connections
- Inspect blower belt wear and tension and adjust as necessary
- Check voltage/amp draws and fan controls on blower and draft inducer motors – verify against plate
- Inspect condition of burner tubes
- Inspect condition of heat exchanger
- Inspect flue for obstructions
- Record gas manifold pressure
- Inspect condensate drain pan – determine if it needs to be cleaned and/or treated
- Inspect evaporator coil – determine if cleaning is required and if solvents required
- Lubricate any components as required
- Inspect cabinets and panels for condition and sealing
- If applicable, check electric heating element amperage and voltage
- Inspect condenser coil to determine if it needs to be cleaned and if solvents are required
- Inspect compressor contactor
- Inspect compressor for oil leaks and check amperage draw – verify against plate
- Check start capacitor and potential relay
- Check cut-out setting for pressure switch
- Record refrigerant pressures and levels
- Inspect expansion valve and record coil temperatures
- If applicable, check if crankcase heater is operational
- Check defrost controls
- Record condenser motor amperage draw – verify against plate
- Lubricate any components as required
- Inspect cabinets and panels for condition and sealing
- For heat pumps, check operation of reversing valve