By: Alfredo Sotolongo*
As I have indicated in previous opinion columns, since the beginning of my professional life, 42 years ago, I have felt great passion for energy conservation. It has always seemed to me that wasting it is like going against nature and for that reason I try to focus on that fascinating subject.
I wonder: what good is the best design and installation of an air conditioning system where the latest energy conservation components and the most efficient equipment have been applied and yet they are not given the appropriate preventive maintenance?
A sad reality
In a large number of the projects that I have visited in the last 42 years in several of our countries in Latin America and the Caribbean islands, I have encountered the sad reality that these projects do not receive the preventive maintenance they need, they are only attended to when they stop operating or operate poorly. This means that they have possibly been wasting energy.
From water treatment, in the condensing water system, to air filters lose their effectiveness by not receiving the preventive maintenance recommended by manufacturers, penalizing the efficiency on which they originally based the design and investment.
Things as simple as cleaning or changing filters, operating outdoor air gates, cleaning sieves or water filters that affect not only the capacity of the system, but also penalize the motor of fans and water pumps.
In water-cooled water condensation systems, which turn out to be the most efficient, the cooling tower is one of the most important components. The chiller depends entirely on the effectiveness of the cooling tower to operate at its maximum efficiency. No matter how efficient the cooler is if the cooling tower is not operating with the effectiveness for which it was selected, the efficiency at which the cooler is capable of operating is never achieved.
For example, in cooling towers in terms of efficiency, Protec Cooling Towers recommends that preventive maintenance be executed as follows:
a) Fan, motor, belts and pulleys or transmission: inspect it for vibration weekly and adjust the screws and nuts monthly.
b) Filling: inspect it twice a year and if necessary, wash it under pressure.
c) Float type valve to replenish water: check for leaks weekly.
d) Water level: inspect daily.
e) Distribution tray: inspect weekly and clean if necessary.
f) Water inlet filter: clean weekly.
In the case of water pumps, whether condensation or ice water, Armstrong recommends that the suction diffuser, which contains the strainer and is located at the entrance of each pump, be measured the pressure drop through the pressure gauge that must be placed in the connection to the inlet of the suction diffuser and the pressure gauge located at the entrance of the pump. In this way, the maintenance manager can determine if the strainer is dirty and clean it. In addition, it is recommended to ensure that the lubrication of the packing is in accordance with the manufacturer's recommendation, which avoids penalizing the pump motor.
Any equipment operating with belts and pulleys should be inspected, at least every 4 months, to confirm that the pulleys are aligned and that it maintains the tension recommended by the manufacturer. Concerned about this condition manufacturers of fans and air extractors, such as Loren Cook, have developed a mechanism that is part of the fan and that automatically maintains the tension in the belts. This prevents them from slipping and helps maintain the efficiency of the equipment.
Other considerations
Another aspect of great importance is to be able to inspect the pressure drop of the air filters in the handling units. Pressure differential pressure gauges must be placed by reading the pressure through each air filter and being able to determine when the pressure drop reaches the final pressure recommended by the filter manufacturer.
In the case of CamfilFarr they publish the initial and final pressure drop, which represents the differential with the clean and dirty filter respectively. The final pressure drop indicates that the filter is saturated, can no longer retain any more dust, and must be changed.
If the maintenance manager requests from the manufacturers of the equipment installed in his project all the preventive maintenance publications and also trains his staff to follow the basic recommendations set out above, I am sure that the vast majority of existing air conditioning systems would operate at the efficiency on which the original design was based and the investment was projected.
*About the author
Engineer Alfredo Sotolongo, president of Protec, Inc., is certified as a professional engineer in Puerto Rico and the State of Florida; has more than 40 years of experience in the application and sale of systems and equipment for energy conservation. He is a member of ASME (American Society of Mechanical Engineers), AEE (Association of Energy Engineers), with whom he is certified as an Engineer in Energy Management; he is also a member of ASHRAE and was president of the Miami chapter of that association. He has also presented numerous talks on the subject of energy conservation.
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