| Frequently Asked Questions (Controllers) |
Considering the cost of installing equipment such as vent boxes and power vent machines, why shouldn't I consider just going with curtain or board cracks as inlets for minimum ventilation?
Just few years back, using curtain cracks and then board inlets with power ventilation was certainly an improvement over natural ventilation, without fans. Today, however, this technology is no longer competitive in many parts of the world. Curtain or board cracks must be controlled manually, if they can be controlled at all. The chief drawback, however, is that they do not allow adequate control of the incoming airflow direction and therefore air mixing in the house. Incoming dense or heavy cold air tends simply to drop toward and chill the birds. Over the life of the equipment, the flock performance gains from much more precise and automatic control of the incoming airflow more than justify the investment costs in most market conditions.
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How do I determine how many perimeter inlets should actually be in use during brooding vs. whole-house ventilation, cold vs. cool to moderate weather, etc?
The key point to realize here is that to provide the good airflow "throw" needed during minimum or transitional ventilation, sidewall air inlets must open at least 2 to 3 inches (5-8 cm) and ceiling inlets must open at least 1 to 1.5 (2.5-4 cm) inches. If the vent boards are not opened wide enough, the incoming air just sort of leaks into the house at the inlets and then falls to the floor. This definitely will happen if we are using too many inlets for the number of fans running. In this situation, the static pressure vent box machine will have to choke the inlet openings down too far in order to maintain static pressure. Typically, during the early days of a growout when we are using only one tunnel fan (or two sidewall fans) at most, we need to latch closed every other inlet in the brood chambers and all the inlets in the growout end. We would unlatch more inlets in the brood chamber only if we anticipated needing to run additional fans. After turnout we typically need to unlatch more inlets in the growout end as more fans are used, and then finally as we get some age on the birds we unlatch them all. The key is to make sure only enough vent boxes are used at each ventilation stage so that they can open wide enough to get good airflow.
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I understand that integrated electronic ventilation controllers can give better control of the in-house environment, but just how important is this to broiler flock performance?
Our modern broilers have a genetic potential for weight gain and feed conversion that just cannot be realized without consistent, on-target temperature control. The answer, then, is that integrated controllers have high payoff potential for any grower producing modern broiler birds in a competitive market situation. Even good conventional thermostats are likely to have accuracy in the plus or minus 5-degree F (±3 degrees C) range (or even greater), where electronic control systems are capable of plus or minus 2-degree F (±1 degree C) control or better. Integrated control systems further make it much more likely that optimum environment will be maintained since they automate the process of adjusting ventilation to changing conditions. It is just impossible to achieve anywhere near that accuracy by manually setting and resetting even the best thermostat systems. The payoff? Commercial broiler companies that have closely monitored thermostat vs electronic control houses report gaining as much as four points in feed conversion by keeping temperatures within 2 degrees F (1 degree C) of optimum.
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Sometimes when I am running minimum ventilation the thermostat kicks the fans on so the fans are running more than they ordinarily do in minimum vent. Is this a problem?
The first thing to check is whether the thermostat setting is too low. It should not be set below the target optimum temperature for that day or week. The key thing to realize is that minimum ventilation applies only when we have some combination of cool weather and/or young birds so that there is no need to exhaust heat from the house. In this situation, the primary control to regulate minimum ventilation is not temperature but the timer or time clock controlling the amount of time that fans are run to bring fresh air into the house. This can be a 10 minute or 5 minute timer or time clock feature that is built into a controller. In this situation, the thermostat is a "fail-safe" to make sure the birds don't get over-heated. As birds grow, the minimum ventilation rate (time on) is increased to take care of the increased moisture they produce. However, as the birds grow larger and/or outside temperature warms consistently, so that the birds are producing enough heat to warm or over-warm themselves and the house, thermostat control must take over.
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What exactly does the term "transitional ventilation" mean in terms of managing my poultry house ventilation?
Usually, the term "transitional ventilation" refers to running some of the house tunnel fans, but bringing air into the house through perimeter inlets instead of through the tunnel inlets. This technique is ideal when we have "in-between" size birds and/or weather. In other words, we need to exhaust more heat from the house than we could with a minimum ventilation setup, but we don't want cool outside air flowing onto the birds. A good transitional ventilation setup will have enough perimeter vents to handle 50% of the tunnel ventilation capacity. Some growers now have eliminated sidewall fans entirely, and use one and sometimes two of the tunnel fans to run minimum ventilation. This tends to blur the distinction between "minimum" and "transitional" modes. The difference is that minimum ventilation is timer-controlled. When the thermostat overrides the timer, signalling that heat removal is needed, we are in transitional mode, whether sidewall or tunnel fans are being used. In most modern houses, electronic controllers manage this transition. However, the controllers themselves require good management oversight, and it is the grower who has ultimate responsibility for determining the best way to control in-house conditions.
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What is the value of using a power vent machine as part of a ventilation system?
The "power vent machine" or static-pressure inlet controller is one of the most important technological advances in poultry ventilation in recent years. It combines a static pressure sensor and inlet actuators to give you automatic adjustment of your sidewall or ceiling air inlets during cool-weather or transitional ventilation. With a power vent machine, you don't have to manually adjust inlets every time conditions change and fans kick on or drop off. A good power vent machine continually adjusts inlets to provide the precise amount of inlet opening needed to shoot air into the house fast enough and high enough to get good mixing and avoid chilling birds. It's important to realize that the power vent machine is actually controlling the house static pressure. To get good airflow through our vent boxes, we need a static pressure of about 0.08 to 0.10 inches (20-25 Pa). The vent machine senses whatever the static pressure is, and either opens up or squeezes down the inlet openings to get static pressure where it needs to be for good airflow.
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When my house is in minimum or transitional ventilation mode with the perimeter inelts running wide open, I don't seem to be getting as good air mixing as when the power vent machine has closed the vent openings down somewhat. What could cause this?
It may be that your vent boxes are opening too wide. This situation especially occurs with sidewall air inlets if the vent board is allowed to rotate past the designed "fully open" position. This is where the distance from the tip of the vent board to the inside top opening of the vent box is equal to the inlet's "throat" width or the width of the outside inlet opening. One of the purposes of the sidewall inlet vent board is to direct the incoming air toward the ceiling. If the board rotates past its fully open position toward the horizontal or even pointing downward, it will allow the incoming air to stream downward onto the birds. Some growers have thought that opening vent boards this wide would be an improvement by allowing a greater volume of air to come in, but this is not true.
Product Categories: Controllers
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