Brioler management in cold weather part1
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This document provides guidance on operating a broiler house during cold weather brooding conditions. It discusses the importance of house tightness and proper air inlet setup to ensure optimal air mixing. It recommends latching inlets closed on the non-brooding end of the house and only opening half of the inlets on the brooding end. Maintaining a static pressure of at least 0.08 inches while using a 1.5-2 inch inlet opening is important for proper air distribution during brooding. Getting the environmental controls, ventilation system, and heating setup correctly from the start of brooding is crucial for optimal bird performance and fuel efficiency throughout the grow-out period.
Brioler management in cold weather part1
- 1. The University of Georgia Cooperative Extension Service College of Agricultural and Environmental Science/Athens, Georgia 30602-4356 Poultry Housing Tips Operating a Modern Broiler House During Cold Weather Volume 15 Number 2 February-March, 2003 PUTTING KNOWLEDGE TO WORK COLLEGE OF AGRICULTURAL AND ENVIRONMENTAL SCIENCES, COLLEGE OF FAMILY AND CONSUMER SCIENCES WARNELL SCHOOL OF FOREST RESOURCES, COLLEGE OF VETERINARY SCIENCES The University of Georgia and Fort Valley State University, the U.S. Department of Agriculture and counties of the state cooperating. The Cooperative Extension Service offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability. An equal opportunity/affirmative action organization committed to a diverse work force
- 2. TABLE OF CONTENTS • Getting Started - House Tightness and Air Inlets 1 • Minimum Ventilation Fans During Partial House Brooding 11 • Circulation Fans During Brooding 13 • Using Environmental Controllers During Brooding 15 • General Controller and House Setup - Partial House Brooding 19 • Minimum Ventilation Chart (Weeks 1 - 3) 21 • Environmental Controller Setup Example (partial house brooding) 22 • General Controller and House Setup - Turning Birds into Full House 23 • Environmental Controller Setup Example (turning birds into full house) 25 • Environmental Controller Setup Example (young birds in full house) 26 • General Controller and House Setup - Older Birds 27 • Minimum Ventilation Chart (Weeks 1 - 7) 30 • Environmental Controller Setup Example (older birds) 31 • General Operating Tips 32
- 3. Setting up a modern broiler house can seem like an overwhelming task at first. How many inlets should I use? What is the correct static pressure? Which fans should I use for minimum ventilation? These are just a few of the questions to be answered. Then of course there are questions related to the environmental controller: What is the best way to set timer fans/cooling fans to minimize fuel usage but at the same time maintain the best brooding conditions? Which sensors should be used to control house temperature? At what temperature should the brooders/furnaces turn on relative to the target temperature? What determines the proper timer fan settings? The purpose of this newsletter is to cover the “how’s” and “why’s” of operating a modern broiler house during cold weather, starting day one, all the way until the day the birds are sold. Though all houses are different, and slight changes may be needed, these guidelines will provide a point from which to start that should help to avoid some of the major problems typically encountered by broiler producers. Getting Started... When it comes to setting up a modern broiler house, if you understand how to set up and operate a house during partial house brooding the remainder of the growout will be a breeze. This is because at no other time during a cold weather growout can ventilating and/or heating incorrectly cost you so much in terms of both fuel usage and bird performance. Variations in house temperature of five degrees that would be considered normal later on during the growout can have a dramatic effect on a day old chick. Ammonia levels that would barely affect the performance of a seven-week-old bird can reduce weight gains of week-old chicks by up to 20%. Air movement that older birds would barely notice can produce a significant wind-chill effect on young chicks even if it is warm. As a result, during brooding, it is all about the fine details. Getting the maximum control over house temperature as well as air exchange is the goal. To accomplish this goal the heating system must be installed and controlled properly, the air inlets need to be operating at their peak efficiency, and last but not least, the environmental controller must be set to coordinate the operation of the equipment to maintain optimal growing conditions without using an excessive amount of fuel. House Tightness and Air Inlets Air inlets are a crucial part of a modern broiler house’s environmental control system. Air inlets allow air drawn in by exhaust fans to be directed along the ceiling to mix with the hot air produced by the birds and brooders/furnaces. (It is important to keep in mind that 50% or more of the heat produced by brooders and furnaces ends up at the ceiling, which results in the temperature of the air at the ceiling being 20oF or warmer than at floor level.) As the air entering through air inlets moves along the ceiling it not only heats up but also becomes “drier.” This is because for every 20oF we heat the incoming air, the moisture-holding ability of the air doubles. So if it is 40oF and raining outside (100% Rh), and we heat the incoming air to 80oF by moving it along the ceiling, the moisture holding ability of the air quadruples resulting in the relative humidity of the air decreasing to 25%. Now, when the incoming air moves down to bird level not only will it be warm, but dry as well. -1-
- 4. 100% 40 F 50 F 75% 60 F 50% 80 F 25% Proper inlet air flow In order to insure maximum heating and drying of all incoming air, we have to make sure that all the air brought in by exhaust fans travels along the ceiling until it makes it to at least the center of the house. The following steps must be taken to accomplish this goal: 1) Make sure your house is as tight as possible. In order to effectively power ventilate during brooding it is crucial that you are able to obtain a static pressure of at least 0.13" with just two 36" fans (one on each side of the brooding curtain) with all the inlets closed. If you cannot obtain a pressure of 0.13", this indicates there are enough excess cracks in your houses to supply all the air the two 36" fans require without even opening the air inlets. Because of these cracks, it will be difficult to effectively use air inlets because if the inlets are opened, the static pressure will decrease to the point at which the air will come in too slowly to create proper air mixing. Poor air mixing will lead to drafts and cold chicks. Cold air entering through cracks in side wall and around loose fitting curtains falling to the floor. -2-
- 5. For instance, let’s say you turned on two 36" fans and you could only obtain a static pressure of 0.07" with all the inlets closed. It is important to realize that though it may appear that the fans are not pulling any air into the house, actually each fan is pulling 10,000 cubic feet of air each minute. The problem is the fans are pulling in fresh air through cracks and not through the inlets, and as a result, cold air is not being thrown along the ceiling to mix with the hot air that collects there during brooding. If you were to open the inlets a couple of inches, the situation would not be improved. When the inlets are opened in a leaky house, the static pressure decreases to very low levels (less than 0.05"). Even though you are now bringing in a portion of your fresh air through the inlets, it still will not be thoroughly mixed with the hot air at the ceiling because as the static pressure decreases the speed at which the air enters the house decreases. To make it to the center of the house where much of the heat produced by your heating system ends up, the air needs to enter with a speed of at least 900 ft/min which requires a static pressure of 0.08" or higher. With a static pressure of 0.05 or less, the air will likely only make it to about the feed line before dropping to the floor. Yes, the air will heat up a little during its short trip the along ceiling, but it can still cause drafts that will adversely affect chick performance possibly resulting in increased mortality, and decreased feed conversions and weight gains. 100% 40 F 50 F 50 F 75% 75% Poor inlet air flow due to excessive leakage through cracks and loose fitting curtains The other important fact to remember is that simply opening the inlets does not mean that all the air is now entering through the inlets and not through the cracks. Though the amount of air entering through the cracks is decreased in a loose house with the inlets open, probably better than half of the air the fans are pulling in is still entering through cracks in the side wall. The key thing to keep in mind is that the higher the static pressure you can obtain with the two 36" fans the more air will be entering through the inlets and lower the amount of air which will enter elsewhere. For instance, if you can obtain a static pressure of 0.20" with two 36" fans you can pretty much be assured that virtually all the air the fans are bringing in will be entering through the inlets and not cracks in the side wall. Could you turn on a third 36" fan to increase the pressure in the house to where you could open the inlets without dropping the pressure to detrimental levels? Sure, and this is what many producers do in looser houses. But the fact remains that a large percentage of your air is still entering through the cracks and not coming in through the inlets where it can be properly mixed with the hot air near the ceiling. -3-
- 6. Using more fans for minimum ventilation to obtain the proper static pressure and inlet opening does not eliminate air entering through cracks and around loose fitting curtains. Another problem with using a third 36" timer fan is that every time they come on you are bringing in a fairly large volume of cold air which tends to drop the house temperature and increase fuel usage. Yes, of course, with three 36" fans you would have a lower timer fan setting than with two, but the fact remains that 30,000 cubic feet of air (three 36" fans) is a lot of air to bring into a house at one time. The larger volume of cold air brought into a house, the more likely house temperature will drop below your target temperature and the more likely the furnaces/brooders will turn on. Think about it...30,000 cubic feet of air is roughly 30% of the total volume of air that is in the brooding area of the typical 500' house. This is why we want to use as few timer fans as possible. Ideally, we want to bring in a smaller volume of air over a longer period rather than a larger volume over a shorter period. If a third 36" fan is required to obtain the desired inlet opening and static pressure combination, it is best if it is on the nonbrooding end. This is because when a third 36" fan is used on the brooding end you will tend to pull cool, ammonia-laden air from the nonbrooding end into the brooding end of the house. Using a third 36" fan should be viewed as a temporary measure. Every effort should be made to work on getting the house tighter so that just the two 36" fans can be used for minimum ventilation. Some ways to look for leakage: a) Place your hand on your side wall curtains. Do you feel a draft? Make sure the curtain is held snugly against the side of the house. b) Examine the top of your side wall. Are there any cracks where cold air is being drawn in? c) Does your tunnel curtain seal tightly at the top and bottom? d) Are your tunnel fan shutters leaking? e) Do your end wall doors close tightly? Leakage at the bottom of the end wall door Dust at the top of side wall curtain indicating air leakage -4- Fan shutters can be a significant source of air leakage
- 7. Before you start looking for leakage, it is important to make sure your 36" fans are well maintained. If the shutters are dirty or the belts are worn or loose, the air-moving capacity of the timer fans can be reduced 30% or more, thus giving the illusion that the house is looser than it really is. Furthermore, make sure the fan is installed tightly against the side wall. If there is a gap between the side wall and the fan housing, the air moved by the fan will not be exhausted from the house but reenter the house through the crack. 2) When half-house brooding, latch closed the inlets on the nonbrooding end of the house. There are a number of reasons why inlets should be latched closed on the nonbrooding end. First and most importantly, allowing the inlets to open on the nonbrooding end can result in very low temperatures on the brooding end. Low temperatures on the nonbrooding end not only can lead to the freezing of water lines but lowers the amount of ammonia which will be “burned off” during the days prior to the birds being turned out into full house. The warmer the nonbrooding end of the house is kept the greater the amount of ammonia that will be “burned off” prior to moving the birds out so when the birds are turned out there will be less ammonia to deal with. Inlets latched closed on nonbrooding end Side wall inlet latch Another potential problem with leaving inlets open in the nonbrooding end is that the amount of air the birds are receiving from the two minimum ventilation fans is cut in half. You have to keep in mind that if the inlets are left open on the nonbrooding end the 36" fan on the nonbrooding end will only bring fresh air into the nonbrooding end. For instance, it is generally recommended that producers run two 36" fans at least 30 seconds to one minute out of five. If the inlets are opened on the nonbrooding end these minimum ventilation settings would have to be doubled to one minute out of five in order to maintain proper air quality. One advantage of latching closed the inlets on the nonbrooding end of the house is that you will end up pulling some of the heat around the brooding curtain to the nonbrooding end prior to exhausting it. Though this heat will typically only increase the temperature of the nonbrooding end around five degrees it is five degrees, that you did not have to pay for which will help in the “burning off’ of ammonia. It is important to note running one 36" fan -5-
- 8. on the nonbrooding end and pulling a little heat to the nonbrooding end is not the same as only using two 36" fans on the nonbrooding end and none on the brooding end. In this scenario, all the air moved by the exhaust fans is brought to the nonbrooding end of the house which can lead to condensation problems. This method of ventilating will be discussed in more detail later. 3) Latch closed half the inlets on the brooding end of the house (this can be either all the inlets on the north or south side of the house or the inlets can be staggered). A modern broiler house typically has 50 to 70 side wall inlets. This number of inlets is primarily required for older birds during warm weather when you may be operating your 36" fans as well as a significant portion of your tunnel fans through the inlets. When all the inlets are used during cold weather, optimum air mixing may not take place. In order to obtain proper air mixing, it takes the proper combination of inlet opening and static pressure. For instance, a static pressure of 0.10" will insure great air speed, but if your inlets are only opened 1/4", the air jet does not have enough mass to make it to the center of the house along the ceiling to help push the warm air down toward the floor. Likewise, a 1 ½" side wall opening is a perfect cold weather opening and will provide sufficient air mass, but if the static pressure is only 0.05", it will not have sufficient speed to make it to the center of the house. To obtain optimal air mixing it takes a static pressure of at least 0.08" and a side wall inlet opening of approximately 1½" to 2" (or a ceiling inlet an opening of 1" to 1 ½"). Inlets latched closed on exhaust fan side of a house Inlets latched closed - staggered 1" ceiling inlet opening 1 ½" side wall inlet opening -6-
- 9. The problem is that in the average house if all the inlets are used on the brooding end, two 36" fans will only draw enough air from the house to get the inlets to open less than a ½” at a static pressure of 0.08". By closing half the inlets what you will end up with is the same pressure and twice the inlet opening. If the inlets open too much, the pressure can be raised to reduce the inlet opening to the proper size. It is important to keep in mind that 0.08" pressure is the minimum static pressure. Static pressures as high as 0.13" are permissible and are actually optimal during very cold weather, again providing you have the proper inlet opening. It is important to realize that just because you may be using half of your inlets, it doesn’t necessarily mean that you will have poor air distribution. First, the air entering through an inlet does not move across the ceiling and then stay on the opposite side of the house from where it entered. As it moves to the floor it moves both toward the opposite side wall, as well as, toward the side wall from where it came providing wall-to-wall distribution of fresh air. Secondly, as the air moves across the house it spreads out longitudinally. So, though the air starts with a four or five foot width, by the time it makes it to the center of the house it will be 10' to 15' in width. So whether you use inlets on one side of a house or staggered you will find that as long as you get the proper inlet opening and static pressure combination you will have few fresh air distribution problems. Air entering through staggered inlets Air entering through inlets on one side of a house -7-