Chiller and Condensing Coil Maintenance
When budgetary constraints are placed on the maintenance of mission-critical equipment industrial process cooling equipment, the results can be catastrophic to the business.
When budgetary constraints are placed on the maintenance of mission-critical equipment industrial process cooling equipment like cooling towers, the results can be catastrophic to the business.
As most facilities and maintenance engineers know, proper maintenance on chiller and condensing units is critical to efficient, trouble-free operation. However, when you combine the fact that most chillers and condensing units are situated in low traffic locations and out of sight (i.e., behind buildings, hidden behind walls or on rooftops) with the fact that the coil-cleaning portion of the maintenance process is an unpleasant and time-consuming task, chiller and condensing unit maintenance isn't one of those jobs that most maintenance engineers look forward to. In situations where the maintenance department is busy or understaffed, coil cleaning is more likely to be deferred beyond the time when maintenance is actually required by the equipment.
It is commonly known that even the slightest coil fouling leads to what can be described as the first level of failure. It is distinguished by the following characteristics:
- Higher operating compressor head pressure, which is caused by elevated refrigerant pressure resulting from restricted airflow and poor heat exchange.
- Reduced cooling capacity, which is caused by poor airflow through the coils.
- Increased kilowatt draw, which is coupled with a reduction in cooling tonnage capacity.
- Extended operating times marked by unit running longer and working harder to achieve setpoint temperature.
- Increased cycling as the compressor cycles off and on under high head pressure. This occurs because the compressor is being stressed under dirty coil conditions, and the system is overheating.
Process chillers suffering from first-level failure conditions pass on the impact in the form of product quality problems and even failure of the process equipment -- computer control equipment, robotic welding systems, injection-molding systems and press equipment -- and can even bring production to a grinding halt.
The Second Level of Failure: A Cooling Tower Example
Consider this real-life situation: A 20-ton chiller used to cool a computer control room of a major automotive parts manufacturer became fouled and was in need of cleaning. Because the maintenance department was short-handed, the staff did not have the time to perform the maintenance when it was needed. So, maintenance was put off for an unspecified period of time. Eventually, the debris load completely fouled the chiller coils, resulting in a second level of failure --with a catastrophic impact on the business.
For this company, the characteristics and cost implications of a second-level chiller failure were:
- The compressor failed.
- The computer room experienced computer failure due to overheating. The company was forced to replace the failed computer equipment while running production at reduced capacity until the chiller was back online.
- Procurement of the new compressor took two days and resulted in two days of downtime and lost productivity on three computer-controlled production lines, translating into a $500,000 per day production loss.
- Management sent home production workers with full pay and benefits until the chiller was back up and running. The company paid production workers for lost productivity.
- The company missed shipments, resulting in customer dissatisfaction.
- Compressor replacement cost was $7,000 to $8,000.
- Compressor installation cost was $3,000 to $5,000.
- Production equipment startup cost following the compressor installation was $10,000, which included the cost of raw material waste resulting from make-ready and production line startup.
- Coil cleaning cost was $1,000 to $2,000.
As you can see, if the coil cleaning and maintenance had been performed before the first level of failure, it would have only cost $1,000 to $2,000; however, because it was deferred and operation continued until the second level of failure, the costs associated with the second failure level exceeded $1 million.
Now, you might be wondering why there wasn't a backup unit in place for this mission critical application. For this manufacturer, the backup consisted of spot coolers that were moved around the computer room to vital locations. However, the spot coolers were used only to augment the cooling when needed, and they were not designed for the full load of the computer room. In this example, the company did not have a true backup chiller; therefore, preventive maintenance should have been of vital importance.
Why Companies Defer Cooling Tower Maintenance
Facilities and maintenance directors cite many different reasons for why they defer maintenance. However, it's important to keep in mind that regardless of the reasons, when equipment is in need of maintenance, deferring it for any reason will not change that fact. Do any of these reasons sound familiar?
Budgetary Constraints. "We'll put off the maintenance until next month so we don't go over budget." When you consider all of the risks to a business associated with a system failure, deferring maintenance due to budgetary constraints is not usually a sound decision. When budgetary constraints are placed on the maintenance of process critical equipment, the results can be catastrophic to the business.
Manpower and Time Constraints. "We'll get around to cleaning the chiller as soon as we can -- we have too many other things to do right now." This reason for deferring maintenance is more common today than ever before. Why? Because companies have been forced to reduce staff and streamline operations to conform to the economic realities of the business, or they cannot find qualified personnel. This places additional demand on maintenance engineers because they now have to do more with less. If chillers and condensing units support process critical operations, then maintenance of those systems should be near the top of the "To Do" list -- even when the maintenance department is busy or short handed.
To help improve maintenance efficiency and reduce the time required for performing the maintenance task, consider outsourcing maintenance to a reliable service company. Also, investigate technologies such as air-intake filters as they can help extend the effective operating window for the chiller. In short, in lean maintenance staffing situations, investment in technologies that can optimize operational efficiency and reduce maintenance should be considered.
Maintenance Complexity and Knowledge Constraints. "Maintaining this equipment is very difficult -- and we don't have the skills to maintain it correctly." This reason is especially common in companies using advanced mechanical systems. Maintenance workers must be trained to properly maintain them, or the maintenance work should be outsourced to a service company that is knowledgeable with the maintenance process.
Unfriendly Maintenance Process. "We hate cleaning chiller and condensing units because it's a dirty job. We get dirt and debris all over us when we powerwash the coils, so we'll clean the coils later." Although cleaning coils is a dirty job, this is not a sound reason for deferring maintenance. When cleaning coils, proper safety equipment including eye and respiratory protection, rubber gloves and protective outerwear should be worn to protect against coil-cleaning chemicals and mold or bacteria that may be present. In addition, air-intake filtration systems isolate debris on the outside of the coils, where it is visible and easy to clean using a broom, brush or shop vacuum.
The list of reasons for deferring maintenance can go on and on, but one thing is clear: Deferring maintenance on process critical equipment can be risky. It can increase the odds that a system failure will occur. If one does, it usually will cost more than the cost of the maintenance that could have prevented the failure in the first place. In the end, the decision for performing or deferring maintenance on chillers and condensing units fall squarely on the shoulders of the maintenance and facilities directors as they balance their maintenance and budgetary decisions, recognizing all the risks involved.