American Coolair Corporation

As published in

FOLLOW PROPER VENTILATION GUIDELINES TO BOOST BIRD PRIDUCTION

Hot weather conditions can begin to have a negative effect on the growth and performance of chickens once temperatures soar into the 90s and low 100s. Recent technological advances such as tunnel ventilation have helped poultry growers keep their birds comfortable, but maintaining consistent in-house temperature can still be a battle with Mother Nature.

Heat stress remains a major problem today for growers, which is why ventilation and cooling systems are such critical points for the success of any poultry farm. The following guidelines will help ensure maximum performance from your ventilation system.

Tunnel Ventilation

The typical broiler house in South America houses 20,000 birds in a 40 x 400 foot space with seven- to nine-foot ceilings. The two biggest factors involved in making this space the most comfortable and efficient for optimal bird production are high air exchange rates and airflow.

From the start, all houses should be designed, maintained and operated for tunnel ventilation. An effective tunnel ventilation system takes into consideration the house size, ceiling height, baffles, type and R-rating of insulation, number of birds, market weight of those birds, and the climate where the house is built. The evaporative cooling system, in turn, is sized to match the tunnel ventilation system.

Tunnel ventilation is the most popular and best method of cooling poultry houses. With tunnel ventilation, the grower is essentially making his house a wind tunnel, pulling the air from one end to the other. This creates a wind chill factor that causes the birds to feel a lower temperature than actually exists in the house.

The wind chill factor can usually decrease the effective temperature by 10 degrees. Keep these key items in mind when trying to optimize your wind chill factor:

"Air speed in a tunnel ventilation system should be 400 to 600 cfm," said Mark Fales, sales manager for American Coolair Corporation, a leading U.S. manufacturer of fans and cooling systems. "Above 600 cfm can be detrimental to the birds."

To determine the number of fans needed to produce an air velocity of 400 cfm through your house, make the following standard calculation:

Fales also suggests a number of basic maintenance tips for growers in hot-weather climates to further ensure proper efficiency.

First, keep a broom handy, Fales said, because it is always a good idea to check the shutters on each fan and brush them down on a regular basis. This will help reduce build-up of dust and bird dander so that shutters can open more freely. And, while a grower is brushing down the fan shutters, he or she should also clean the fan blades (only do this when the fans are NOT in operation). Dirt and dust build-up can and will affect the performance of your cooling system.

Shutters also should be lubricated with antifreeze to aid in opening and closing. However, petroleum-based products should not be used, because they can cause pivot pins, made of nylon, to deteriorate. If a grower is unsure of what kind of lubrication to use, he should check with his supplier, as all shutters are different.

Growers should also avoid having shutters screwed too tightly into the walls of a chicken house, which does not allow them to operate correctly. Fales said shutters should be allowed to float freely. Also, when installing fans, wires connected to the motor of the fan should not be run through the shutters since this could hinder them from opening and closing freely.

Fales said growers should be wary of spray washing fans and never to wash down fans if they have not been turned off for at least two hours.

"That's the quickest way to ruin a fan, so take all the necessary steps to keep moisture out of the bearings," Fales said.

Belt-drive fans are the ones most commonly used for tunnel ventilation. Belt tension is important, and belts must be lined up on the pulleys. They also should be replaced every 18-24 months to optimize fan efficiency.

Fan vibration can occur when one of the blades is out of track or pitch. It also can happen if the fan unit or propeller is out of balance.

"Track or pitch is a more common problem than the fan unit being out of balance," Fales said. "We (American Coolair) have a tool kit that can be sent into the field that comes with a set of instructions specific to Coolair fans to properly align the fans."

Repairing the fan unit is much more difficult. Fales suggests contacting the fan manufacturer and getting directions on statically balancing the blade and always using original manufacturer replacement parts.

The physical structure of a house plays a big factor in what sort of ventilation and cooling systems you need as well. As mentioned earlier, the height of the ceiling is one factor determining how many fans a house needs to operate efficiently.

Consequently, reducing the height of your house is an easy way to lower the total air volume. For maximum efficiency, a ceiling should be no higher than 9 feet. Baffles are a cheap way to reduce height; adding baffles every 35 to 40 feet forces the air to flow down. Proper insulation is another vital part in improving overall efficiency.

"The roof should be insulated as well. R-11 is recommended, and R-19 is even better," Fales said. "If you have properly insulated your house, then the majority of the heat generated in the house is coming from the birds, and you can pretty much negate outside heat. But without insulation, you might achieve the correct air speeds, but you'll lower your efficiency tremendously since you'll have solar heat on top of the bird heat gain."

While tunnel ventilation systems are sized according to several factors, the evaporative cooling system is sized to match the ventilation system that a grower has chosen for his or her poultry house. Undersizing evaporative cooling systems, which reduces total pad surface, can result in excessively high static pressure, which causes lower air speeds and a cooling efficiency that's less than desirable.

The proper pairing of your ventilation system with an evaporative cooling system is extremely important when trying to reduce the mortality rates caused by heat stress during the hottest days of the summer. It's important to remember that since the evaporative cooling system is working with tunnel ventilation, you only need to bring the air temperature down to the range where the wind chill factor helps the birds feel as if the inside temperature is 70 degrees. For example, if the outside temperature is 94 degrees, then you can reduce the temperature by 12 degrees with the evaporative cooling system, while the wind chill factor will reduce the effective temperature another 10 degrees. It will feel like 71 degrees to the birds.

To extend the life of your pads, they should be dried out once every 24 hours to disallow allergy build-up. They can be dried during the coolest part of the day, when the cooling system is not needed to keep the birds comfortable. However, if there are dry spots on the pads during the peak temperatures of the day, check water lines for blockages.

When choosing your brand of pads, one should make sure to check their efficiency rating. This rating is measured by the speed of air traveling through the pads. The slower the air speed the more efficient the pads are because there is more time for the moisture to cool the air.

Maintaining proper house temperature and ventilation are just as important as providing sufficient food and water for the birds. That's why it's vital that growers take the time to do "the little things" to ensure proper fan and temperature control, because each of these measures adds up to healthier flocks, more efficient operations, and ultimately a higher profit margin.