High Broiler Flock Performance Depends Predominantly on Accuracy and Efficiency of Ventilation System. During minimum ventilation periods, producers are concerned about moisture, litter condition, keeping the birds warm, and air quality. The more control producers have over air quality, air temperature, and energy usage the more control they will have over their paycheck at the end of the grow-out.
The concept of poultry minimum ventilation is utilizing a negative pressure system that creates a vacuum inside of the house. The pressure created is uniform throughout the entire house, so air will enter through all of the inlets. This includes not only planned ceiling and sidewall inlets, but it also includes all of the “unplanned” inlets; such as: shutters, sill plate, tunnel doors, and end wall doors. Inlets control direction and velocity of the air entering the house, and therefore air mixing. Every single area of the house that is not sealed up correctly will leak air into the house as an “unplanned” inlet.
An Ideal Ventilation System Will Bring All of the Air into the House Through Sidewall Inlets
Air entering through properly designed sidewall inlets will allow the air jet to attach to the ceiling, travel along the ceiling until it makes it to the center of the house, and gently move down toward the floor. It is essential to maximize the travel distance along the ceiling so the cool incoming air will be sufficiently heated by the warm air collecting at the ceiling.
The mixing of the cool, damp air with the warm air at the top of the house is great for air mixing, but the uniform temperature being created isn’t automatically the greatest benefit to be reaped from this system.
A warmer, uniform temperature gradient is desirable, but the major key is the moisture holding capacity of the air that is maximized as this air is heating up. Every time the air is warmed up 20 degrees, the moisture holding capacity of the air roughly doubles. When the incoming air is warmed sufficiently using proper inlets, the grower has direct control of the capacity of water that the air can pick up from inside the house. As the air moves over the litter, it picks up moisture from the litter and exhausts that extra moisture out of the house. This leads to drier litter and a more uniform temperature and air quality gradient across the entire house.
Advantages of Ceiling Inlets in Cooler Climates
Ceiling inlets in colder climates are a great tool to be utilized. During the coldest days of the year, ceiling inlets are used to bring in warm air from the attic and disperse it into the house. The ceiling inlets are installed in a prime location inside the house where there is not a large temperature difference on either side of the inlet. This is an advantage because the grower doesn’t have to stress about inlets freezing up on the coldest days.
“Unplanned” inlets drastically decrease the efficiency of the ventilation system and the air inlet system. Every square foot of leakage that is present in a house during minimum ventilation will result in a lower percentage of the air entering through the sidewall inlets where the air is properly conditioned. Cold, damp air entering through the fan shutters, cracks in the sidewalls, tunnel doors, and tunnel curtains will tend to drop quickly to the floor. This air will chill the birds and doesn’t have a large capacity to remove moisture from the litter. It tends to form condensation on the litter adding excess moisture.
One of the biggest concerns when trying to control litter moisture is how to keep heating costs to a minimum. It will always take some amount of heat to control litter moisture during cold weather, but how much depends to a large extent on the performance of the houses’ inlet system. House tightness is critical in empowering the grower to establish the control of his / her houses and his or her paychecks. The tighter a house is, the more control the grower will have over the entire ventilation system as a whole.
As the poultry industry is evolving, house design and construction are evolving too. The basic principles outlined here about ideal air mixing become more difficult to achieve in the wider houses (larger than 60 ft. wide) without the correct equipment. The European Sidewall Inlet with the curved blade is the ideal design to achieve complete air mixing in houses. The curved blade helps direct more air across the ceiling and creates an efficient air jet that will reach the center of these wider houses with ease.
Utilizing an older style galvanized door would result in a decrease in efficiency and ultimately more stale and damp air through the center of the house. Trying to properly ventilate a “super house” without utilizing a curved blade is similar to trying to win the Super Bowl with a soccer ball. If you don’t start out with the appropriate equipment, you are inherently setting the system up to fail or not perform efficiently.
Stir Fans Create more Uniform Temperatures in Poultry House
A circulation fan system is used to break up temperature stratification and create more uniform conditions from one end of a house to the other. It is used just as importantly to increase the level of air movement over the litter to aid in moisture removal. A proper circulation fan system gently moves air across the litter while ensuring the birds are not being chilled. As that air moves across the litter, it picks up moisture from the litter to be exhausted out of the house. It is a very practical and efficient way to cut heating costs in houses drastically in the winter time, and also improve in-house conditions overall.