Evaporative Cooling Pad Maintenance Tips

When it comes to keeping birds cool during hot weather, air speed remains a grower’s most effective tool for combating heat stress. Air movement can lower the effective temperature experienced by a bird by 10°F or more because moving air removes body heat much more rapidly than still air. However, as house temperature climbs above approximately 85°F, the cooling benefit of air movement begins to decline because warmer air is less capable of carrying heat away from the birds. Evaporative cool...ing pads help solve this problem by lowering the temperature of the air moving over the birds. Their purpose is not to replace air speed, but make sure that the air movement created by the tunnel fans remains effective at keeping the birds comfortable on the hottest of summer days.

As outside air passes through a wetted pad, a portion of the water evaporates, removing heat from the incoming air and therefore lowering the temperature of the air. Although the amount of cooling produced will vary with outside temperature and humidity, properly functioning pads often make the difference between birds remaining comfortable and experiencing significant heat stress during hot afternoons. Unfortunately, dust, algae, feathers, and mineral deposits slowly reduce pad performance. Restricted airflow increases static pressure, reduces fan capacity, raises electrical costs, and allows the temperature difference between the inlet and fan ends of the house to increase. Because the pad system and tunnel fans work together, neglecting the pads eventually reduces the effectiveness of the entire tunnel ventilation system.

The following are a few ways to help maximize pad performance while at the same time maximizing pad life:

Maintain Uniform Water Distribution
Uniform water distribution is the foundation of an efficient evaporative cooling system. Water should flow evenly over the entire outside surface of every pad. Keep distribution pipe holes clean so water is applied uniformly across the full length of the pad. Inspect the system while it is operating and look for dry areas, plugged holes, leaking fittings, or uneven flow from one end of the system to the other. Correcting these small problems early helps prevent permanent mineral deposits from forming and ensures the entire pad contributes to cooling.

Make sure you have a trash trap installed at the end of each water distribution pipe. Install an elbow fitting at the end of the distribution pipe and connect it to a vertical, two-foot-long PVC pipe with a ball valve at the bottom. As water flows through the distribution pipe, it will push trash such as bugs, feathers, and seeds into the vertical pipe instead of through the holes in the top of the distribution pipe. Opening the ball valve once a week while the pad system is being used will help remove this trash from the system.

Monitor Air Velocity Through the Pads
Mineral deposits, dirt, and algae on pad surfaces can restrict airflow long before it becomes obvious. An inexpensive air velocity meter provides an objective measure of pad performance. Hold the meter one to two inches from the center of a six-inch pad while all the tunnel fans are operating. Air velocity should generally range from 325 to 375 ft/min when all the fans are operating. If readings are lower, inspect the pad for mineral deposits, algae, or dirt. Before assuming the pad is the problem, verify that the fans are clean, the shutters operate freely, the belts are in good condition, and the house is reasonably tight. Dirty fans and air leakage reduce the amount of air passing through the pads, making the pads appear to be underperforming when the problem actually lies elsewhere.

Prevent Algae and Mineral Buildup
Algae and mineral deposits are among the most common causes of declining pad performance. Allow the pads to dry completely once each day whenever cooling is no longer needed. A daily dry-out period discourages algae growth because algae require continuous moisture to survive. Avoid chlorine- and bromine-based products because they gradually weaken cellulose pad material. Products based on quaternary amines generally provide effective algae control without damaging the pads.

Water quality also deserves attention. Hard water leaves calcium deposits behind as the water evaporates. Over time, these deposits reduce airflow, increase static pressure, interfere with water distribution, and shorten pad life.

It is a good practice to dump the water from the pad system every week or two during summertime flocks. As water evaporates from the pad system, the minerals in the water remain behind. Over time, the water becomes increasingly concentrated with minerals, increasing the likelihood of mineral buildup on the pads. Dumping the system also helps minimize algae growth because recirculated water can become rich in nutrients that encourage algae growth.

Protect the Physical Condition of the Pads
The physical condition of the pads is just as important as keeping them clean. Avoid removing pads for cleaning whenever possible because the top and bottom edges are easily damaged, and leaks frequently develop after reinstallation. Doghouse installations allow both sides of the pads to be cleaned while they remain in place. Maintain approximately a one-inch gap between the bottom of the pads and the gutter so standing water cannot keep them wet between operating cycles. Inspect flute angles, coatings, and pad edges each season. Pads that lose rigidity, sag, or develop damaged edges create higher static pressure and reduce airflow.

Monitor Static Pressure
With all the fans operating, static pressure should not increase by more than 0.01 inches when the pads become wet. If it does, it is a sign that the pads may need cleaning.

If you have a static pressure/magnehelic gauge you can measure the pressure drop across the pads to determine if they need cleaning or replacing. If you are standing inside the house at the center of the pad system and run a hose connected to the “high/+” port on the magnehelic gauge through the pads to the outside, the pressure should be around 0.05" with all the fans operating. If the pressure is a couple of points higher, the pads need cleaning. If it is 0.10", then the pads likely need to be replaced.

Remember That Pads Support Air Speed
The most important point to remember is that evaporative cooling pads do not cool birds directly. Air movement remains the primary tool for removing heat from the birds. Cooling pads simply lower the temperature of the incoming air so tunnel ventilation can continue producing an effective wind-chill effect. A clean pad system allows tunnel fans to deliver their designed airflow while providing cooler air to the birds.

Routine inspection, proper water management, algae control, and periodic airflow measurements require little time but can significantly improve bird comfort, reduce electrical costs, and extend pad life. Just as importantly, a well-maintained pad system helps maintain more uniform temperatures from the inlet end to the fan end of the house, reducing hot spots where birds are more likely to experience heat stress. By treating the evaporative cooling system as an integral part of the tunnel ventilation system rather than as a separate piece of equipment, growers can maintain more uniform house temperatures, reduce heat stress, improve feed consumption and weight gain during hot weather, and achieve better flock performance throughout the summer.