Tunnel ventilation is used when barn temperatures are above the ability of transition ventilation to maintain target temperatures. Air enters at one end of a poultry barn and is exhausted by ventilation fans at the other end. The exhaust fans pull air out of the barn, creating a negative pressure as air enters inlets at the opposite end.
Target is to keep turkeys in the thermal neutral zone. For birds 12 weeks or older, this is 55⁰F - 75⁰F (13⁰C - 24⁰C)
Tunnel ventilation involves creating enough air velocity to provide cooling through wind chill. Above is a graph (provided by North Carolina State University) demonstrating the cooling effect of air velocity
There are three primary goals of a tunnel ventilation system
- Remove heat from the house - provide adequate air exchange
- Remove heat from the birds - produce proper air velocity over the birds
- Reduce the temperature of incoming air - adequate evaporative cooling system
An example of effective tunnel ventilation to achieve the target comfort zone. Using imperial measures, the example above is a situation where the temperature in the barn is 85°F. The air speed of the fans provide 15°F of wind chill cooling. The barn is then cooled to the comfort zone of 70°F
For curtain-sided house, roll the curtains down completely with bird wire clean for maximum air flow. Next, make sure fan belts are tight. A worn out belt can reduce fan efficiency by 30% or more. If the sides of the fan belt are worn, the belt will tend to ride lower in the fan and motor pulleys, decreasing the speed at which the fan rotates. Next, clean your fan shutters for improved wind speeds. Dust and feathers can easily accumulate and decrease the efficiency of your fans
Example of tunnel control set up by age
With each set up example listed in the table below, it is important to remember that wind speeds, fpm (feet per minute) or m/s (meter per second), are estimates. Air speed should be checked with a wind speed meter. Wind chill and effective temperatures are theoretical, so look at bird behavior to check if they are too hot (panting) or too cold (huddling and sitting down), and adjust from there.
|Age||Target temp˚F||Fans (quantity x size)||Timer on (˚F )||Timer off (˚F )||Wind chill (at 85˚F )||Effective temperature (timer on)||Effective temperature (timer off)||Wind speed (feet per minute)|
|2-12 weeks||68||2 x 54"||76||74||1||75||73||150 fpm|
|2-12 weeks||68||3 x 54"||78||77||3||75||74||225 fpm|
|2-12 weeks||68||4 x 54"||80||79||7||73||72||300 fpm|
|2-12 weeks||68||5 x 54"||82||80||9||73||71||350 fpm|
|2-12 weeks||68||6 x 54"||84||82||11||73||71||450 fpm|
|2-12 weeks||68||8 x 54"||86||84||13||73||71||550 fpm|
|2-12 weeks||68||10 x 54"||88||86||15||73||71||600 fpm|
Contact one of our Hybrid representatives if you need assistance setting up or managing your ventilation system.