Broiler House Cooling Systems: Evaporative and Fogging Options

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

Evaporative cooling pads are most effective in dry climates (low relative humidity < 80%), achieving a 10-20°F temperature drop by absorbing heat as water evaporates from the pads into the incoming air. Cellulose pads offer higher saturation efficiency (85-90%) and longevity (5-8 years) compared to aspen pads (60-70% efficiency, 1-2 year lifespan).
Fogging systems cool birds directly by atomizing water into fine droplets (10-20 microns for high-pressure, 50-100 microns for low-pressure) that evaporate within the house, making them suitable for humid climates where pads lose effectiveness. High-pressure systems minimize litter wetting, while low-pressure systems require careful ventilation management to avoid excess moisture.
Both systems necessitate adequate tunnel ventilation (prerequisite for effective cooling) and are best operated in stages, beginning with fans alone, then introducing evaporative cooling or fogging only when bird comfort is compromised, as indicated by panting and wing spreading, not just ambient temperature.
Water quality is critical; high mineral content (hardness > 150 ppm CaCO3, iron > 0.3 ppm, manganese > 0.05 ppm) will clog fogger nozzles and reduce pad efficiency, necessitating water treatment such as softening or filtration to prevent scale buildup and ensure optimal system performance.
Sizing is based on fan capacity: evaporative pads require approximately 1 sq ft of pad area per 250-400 CFM of tunnel fan capacity, while fogging systems are sized by nozzle flow rate, aiming for roughly 1 gallon of water per hour per 1,000 CFM of fan capacity.
Monitoring bird behavior (panting, wing spreading, activity levels, water consumption) is paramount for determining actual cooling needs, as these are more reliable indicators of heat stress than thermometers alone, guiding the activation and adjustment of cooling systems.

Broilers perform best when house temperatures stay within the thermoneutral zone, roughly 65 to 75 degrees Fahrenheit for most ages. When temperatures climb above that range, birds reduce feed intake, pant more, and divert energy away from growth. This guide compares the two main active cooling approaches used in commercial and small-scale broiler houses: evaporative cooling pads and fogging systems. It covers how each system works, how to size and install components, how to operate them with tunnel or circulation fans, and how to avoid the common mistakes that lead to wet litter, respiratory issues, or wasted water. The intended audience is broiler growers, farm managers, and poultry service technicians who want a practical decision framework for choosing and running a cooling system that fits their house design, climate, and budget.

At a Glance

Evaporative cooling pads cool incoming air by 10 to 20 degrees Fahrenheit when humidity is low, but they lose effectiveness as relative humidity rises above 80 percent.
Fogging systems cool birds directly by wetting their feathers and skin, which works even when humidity is high, but they add moisture to the litter and require careful attention to ventilation.
Tunnel ventilation is a prerequisite for both systems in most climates. Without adequate air exchange, neither pads nor foggers can prevent heat stress.
Choose pads for dry climates and for houses where you can maintain tight air inlet seals. Choose fogging for humid climates or as a retrofit when structural changes are not possible.
Run cooling in stages based on temperature. Start with fans alone, then add evaporative cooling only when fan capacity alone cannot keep birds comfortable.
Monitor water quality for both systems. Hard water or high mineral content will clog nozzles and reduce pad life.
Check birds, not just thermometers. Panting, wing spreading, and reduced activity are the real indicators that cooling is needed.
Keep detailed records of water use, run time, pad condition, and bird behavior so you can adjust settings week by week.

Understanding Heat Stress in Broilers

Broilers are more sensitive to heat than many other livestock because they have a high metabolic rate, a dense feather cover, and no sweat glands. They lose heat through four main routes: radiation, convection, conduction, and evaporation. Radiation and convection require the air around the bird to be cooler than the bird's surface temperature, which is usually around 104 to 106 degrees Fahrenheit. When air temperature approaches that range, those passive heat loss routes stop working. The bird then relies almost entirely on evaporative cooling through panting, which costs energy and water.

Panting increases moisture loss from the respiratory tract. At high temperatures, a broiler may double or triple its respiration rate. This drives up water consumption and reduces feed intake. When a bird cannot shed enough heat, its body temperature rises. A rise of just a few degrees above normal can reduce weight gain, weaken the immune system, and in severe cases cause death. The economic impact of heat stress is not limited to mortality. Even birds that survive a hot day often show reduced feed conversion for several days afterward.

The temperature-humidity index is a useful way to judge risk. It combines air temperature and relative humidity into a single number. A THI below 80 is generally safe for most broilers. Between 80 and 85, birds begin to show signs of heat stress. Above 85, performance drops sharply and mortality risk increases. The THI matters because evaporative cooling depends on humidity. On a dry day at 100 degrees with 20 percent humidity, evaporative cooling is highly effective. On a humid day at 90 degrees with 80 percent humidity, the same system will do very little.

Bird age also matters. Young chicks cannot regulate body temperature well and need heat, not cooling. Cooling systems are typically not needed until birds are at least 2 to 3 weeks old. By week 4, broilers produce significant metabolic heat and become vulnerable to high house temperatures. The heaviest birds in the house, often the males, are at greatest risk because they generate more heat and have more body mass to cool.

How Evaporative Cooling Works

Evaporative cooling pads work on a simple physical principle. When warm dry air passes over a wet surface, water evaporates into the air. The evaporation process absorbs heat from the air, lowering its temperature. The air that enters the house through the pads is cooler and more humid than the outside air. This cool air then moves across the birds, picking up heat and moisture before it is exhausted by fans.

The effectiveness of evaporative cooling depends on the difference between the dry bulb temperature and the wet bulb temperature. The dry bulb temperature is what a standard thermometer reads. The wet bulb temperature is what a thermometer reads when its bulb is wrapped in a wet cloth and air moves past it. The difference between the two is called the depression. On a dry day, the depression might be 30 degrees or more. On a humid day, it might be only 5 degrees. A well-designed pad system can achieve 70 to 90 percent of the theoretical depression. So on a day with a 100 degree dry bulb and a 70 degree wet bulb, the depression is 30 degrees. A system operating at 80 percent efficiency would deliver air at about 76 degrees.

The two most common pad materials are cellulose and aspen. Cellulose pads are made from corrugated paper bonded together with a rigid resin. They are more expensive but last longer, typically 5 to 8 years with proper care. They also cool more efficiently, often achieving 85 to 90 percent saturation efficiency. Aspen pads are made from wood shavings held in a wire frame. They are cheaper but need replacement every 1 to 2 years and cool at only 60 to 70 percent efficiency. For a permanent installation, cellulose is the better investment.

Pad systems require a water distribution system. Water is pumped to the top of the pad and allowed to run down the face of the pad by gravity. A distribution header, usually a pipe with holes or nozzles, spreads water across the top edge. The water flows down the corrugated channels and evaporates as air passes through. A sump tank at the bottom catches the water that does not evaporate and recirculates it. A float valve maintains the water level in the sump, and a bleed-off line removes a small amount of water to prevent mineral buildup.

The pads must be sized to match the fan capacity of the house. The rule of thumb is 1 square foot of pad area for every 250 to 400 CFM of fan capacity. A house with 100,000 CFM of tunnel fan capacity would need 250 to 400 square feet of pad area. The exact number depends on the pad thickness. A 4 inch pad can handle about 250 CFM per square foot. A 6 inch pad can handle about 400 CFM per square foot. Thicker pads cool more but also create more static pressure, which reduces fan performance.

How Fogging Systems Work

Fogging systems take a different approach. Instead of cooling the air before it enters the house, fogging systems spray fine water droplets directly into the air inside the house. The droplets evaporate, absorbing heat from the surrounding air. The key difference is that fogging can cool the air inside the house, not just the incoming air. In a tunnel-ventilated house, foggers are often placed near the air inlets so the incoming air picks up moisture as it enters.

There are two main types of fogging systems: high-pressure and low-pressure. High-pressure systems operate at 800 to 1,000 psi and produce very fine droplets, typically 10 to 20 microns in diameter. These droplets evaporate quickly, so they cool the air without wetting the birds or the litter. High-pressure systems are more expensive to install because they require a specialized pump, stainless steel or nylon tubing, and precision nozzles. Low-pressure systems operate at 100 to 300 psi and produce larger droplets, typically 50 to 100 microns. These droplets evaporate more slowly and are more likely to settle on birds, litter, and equipment. Low-pressure systems are cheaper but require careful management to avoid wet litter.

The placement of fogger nozzles is critical. In a tunnel house, nozzles should be arranged in a grid pattern across the ceiling or along the side walls near the air inlet. The goal is to distribute droplets evenly so that evaporation occurs before the air reaches the birds. If nozzles are placed too close to the birds, large droplets will fall on them. If they are placed too far from the inlet, the air will already be warm when it reaches the foggers, reducing the cooling effect.

Fogging systems are controlled by a thermostat or a controller that reads both temperature and humidity. The controller turns the foggers on when the temperature exceeds a set point and turns them off when the humidity reaches a maximum threshold, usually 80 to 85 percent. Above that humidity level, additional fogging does not cool the air because the air is already nearly saturated. The water will just wet the litter and the birds.

One advantage of fogging is that it can be added to an existing house without major structural changes. Pads require cutting openings in the side walls and installing a water distribution system. Foggers only need a water line, a pump, and nozzles mounted on the ceiling or walls. For a grower who wants to retrofit an older house, fogging is often the more practical option.

Comparing Evaporative Cooling and Fogging

The choice between pads and foggers depends on climate, house design, water quality, and budget. There is no single best system for every situation.

In dry climates, evaporative cooling pads are the superior choice. They deliver cooler air, keep the house drier, and do not wet the birds. A pad system on a dry day can drop incoming air temperature by 20 degrees or more. This gives the grower a large margin of safety even during extreme heat events. Pads also work well with tunnel ventilation because they cool the air before it enters the house, so the full length of the house benefits.

In humid climates, pads lose their advantage. When relative humidity is above 80 percent, a pad system may only drop the air temperature by 3 to 5 degrees. The pads still add moisture to the air, which raises the humidity inside the house. This can make the birds more uncomfortable because they cannot evaporate moisture from their respiratory tract as easily. In these conditions, fogging can be more effective because it cools the birds directly. The fine droplets evaporate off the birds' skin and feathers, removing heat even when the air is humid.

Fogging has a lower upfront cost in most cases. A basic low-pressure system can be installed for a fraction of the cost of a pad system. However, the operating costs can be higher because foggers use more water and require more frequent maintenance. Nozzles clog, pumps wear out, and water treatment chemicals add to the cost. Pad systems are more expensive to install but have lower ongoing maintenance costs if the water quality is good.

Water quality is a deciding factor. Both systems suffer when the water has high mineral content. Hard water leaves scale on pads, which reduces their ability to absorb water and cool air. The same minerals clog fogger nozzles, sometimes within days. If your water is hard, you will need a water softener or a chemical treatment program. The cost of water treatment should be included in the comparison.

House design also matters. Pad systems require a large opening on one end of the house and a tight seal around the pads. If the house has cracks or gaps, air will enter through those gaps instead of through the pads, reducing cooling efficiency. Fogging does not require a tight house, so it is often a better choice for older houses with poor seals.

Sizing and Installing an Evaporative Cooling System

Before you buy any equipment, calculate the cooling load for your house. The first step is to determine the total fan capacity. Add up the CFM ratings of all the tunnel fans. If you do not know the ratings, check the fan nameplate or the manufacturer's literature. A typical 36 inch fan moves about 10,000 CFM. A 48 inch fan moves about 20,000 CFM. A 54 inch fan moves about 25,000 CFM.

Once you know the total fan capacity, calculate the pad area. For 4 inch pads, divide the total CFM by 250. For 6 inch pads, divide by 400. A house with 120,000 CFM of tunnel fan capacity would need 480 square feet of 4 inch pads or 300 square feet of 6 inch pads. You can split the pad area between both side walls or put it all on one end wall. In most houses, pads are installed on both side walls near the air inlet end.

The pad frame must be sized to hold the pads securely and direct water into a sump. The frame is usually made of aluminum or galvanized steel. The pads sit in a channel at the bottom that collects water and directs it to the sump. The top of the frame has a distribution header that delivers water across the full width of the pad. The header should have a valve to adjust the flow rate. Too much water wastes energy and can cause the pad to saturate. Too little water leaves dry spots that reduce cooling.

The sump tank should hold at least 1 gallon of water for every 10 square feet of pad area. A 400 square foot pad system needs a 40 gallon sump. The sump should have a pump, a float valve, and a bleed-off line. The pump should be sized to deliver 1 to 2 gallons per minute for every 10 square feet of pad area. The bleed-off line should remove 10 to 20 percent of the recirculated water to prevent mineral buildup.

Install the pads so that the corrugations run vertically. This allows water to flow down the pad and air to pass through horizontally. The pad should be installed with the air flow direction marked on the pad. Installing a pad backwards will reduce its life and cooling efficiency. Most cellulose pads have a smooth side and a rough side. The smooth side faces the incoming air. The rough side faces the house.

The water supply line to the sump should have a filter to remove sediment. A 100 mesh screen is adequate for most systems. The pump intake should also have a strainer. Check the strainer weekly and clean it as needed. The distribution header should be flushed weekly to remove any debris that accumulates in the holes.

Sizing and Installing a Fogging System

Fogging system sizing starts with the nozzle flow rate and the number of nozzles. The goal is to deliver enough water to cool the air without saturating it. A common starting point is 1 gallon of water per hour per 1,000 CFM of tunnel fan capacity. A house with 120,000 CFM would need 120 gallons per hour of fogging capacity. If each nozzle delivers 5 gallons per hour, you would need 24 nozzles.

The nozzle spacing depends on the droplet size and the air flow pattern. High-pressure nozzles with very fine droplets can be spaced 8 to 10 feet apart in a grid pattern. Low-pressure nozzles with larger droplets should be spaced closer, 4 to 6 feet apart. The nozzles should be mounted at least 6 feet above the floor to give the droplets time to evaporate before they reach the birds.

The water supply to the fogging system must be filtered to remove particles that would clog the nozzles. A 50 micron filter is recommended for high-pressure systems. A 100 micron filter is adequate for low-pressure systems. The filter should be cleaned weekly and replaced when it shows signs of wear.

The pump should be sized to deliver the required flow rate at the operating pressure. High-pressure systems need a pump that can deliver 1 to 2 gallons per minute at 800 to 1,000 psi. Low-pressure systems need a pump that can deliver 2 to 4 gallons per minute at 100 to 300 psi. The pump should be installed in a location that is protected from dust and moisture. It should be mounted on a concrete pad or a sturdy frame to reduce vibration.

The controller for a fogging system should read both temperature and humidity. A simple thermostat that turns the foggers on at a set temperature is not adequate because it will run the foggers even when the humidity is too high. A good controller has separate set points for temperature and humidity. It turns the foggers on when the temperature exceeds the set point and the humidity is below the maximum. It turns the foggers off when either condition is not met.

Operating the Cooling System in Stages

The most common mistake in broiler house cooling is turning on the cooling system too early or running it too hard. Cooling is expensive and adds moisture to the house. It should be used only when fans alone cannot keep the birds comfortable.

Stage one is fan-only cooling. Increase the tunnel fan capacity as the temperature rises. The goal is to maintain an air speed of 400 to 600 feet per minute across the birds. At this air speed, the wind chill effect can make the birds feel 5 to 10 degrees cooler than the actual air temperature. Most growers start with one or two tunnel fans and add more as the birds grow and the temperature rises.

Stage two is evaporative cooling. When the temperature reaches the point where fans alone cannot keep the birds below their target body temperature, start the cooling system. The set point depends on bird age and outside humidity. A common starting point is 85 degrees for birds over 3 weeks old. Some growers use a lower set point for older, heavier birds. The key is to start the cooling system before the birds show signs of severe heat stress.

For pad systems, start with a reduced water flow. Run the pump at 50 percent capacity for the first 10 minutes to wet the pads gradually. Then increase to full flow. This prevents a sudden surge of cold air that can shock the birds. The pads should be kept wet across their full face. Check for dry spots and adjust the distribution header if needed.

For fogging systems, run the system in cycles rather than continuously. A common approach is to run the foggers for 30 seconds, then off for 2 to 3 minutes. This gives the droplets time to evaporate before the next burst. The controller should be set to increase the duty cycle as the temperature rises. At very high temperatures, the foggers may run continuously, but only if the humidity remains below 80 percent.

Stage three is emergency cooling. When the temperature exceeds 95 degrees and the birds are showing severe signs of heat stress, use every tool available. Increase fan speed to maximum, run the cooling system at full capacity, and consider additional measures such as spraying the roof with water or using sprinklers on the outside of the house. In extreme cases, you may need to reduce bird density by removing some birds to a cooler location.

Monitoring Bird Behavior

The thermostat and humidity sensor tell you what the environment is doing. The birds tell you how the environment is affecting them. You must check the birds regularly, especially during the hottest part of the day.

Healthy broilers at a comfortable temperature are active, feed readily, and distribute evenly across the house. As heat stress begins, birds reduce activity and move away from the hottest areas. They may crowd near the air inlets or the side walls where the air is cooler. Panting is the next sign. Birds begin to breathe rapidly with their beaks open. At first, panting is intermittent. As heat stress increases, panting becomes continuous.

Wing spreading is a late sign of heat stress. Birds hold their wings away from their bodies to expose the less feathered areas under the wings to the air. This increases heat loss by convection. Birds that are severely heat stressed may lie on their sides, breathe rapidly, and appear unresponsive. These birds are in danger of dying and need immediate intervention.

The best way to monitor birds is to walk the house during the hottest part of the day, usually between 2 and 5 PM. Look at the birds in the hottest areas, which are typically the middle of the house and the end opposite the air inlets. Count the number of birds that are panting. If more than 10 percent of the birds are panting continuously, increase the cooling. If birds are spread evenly and active, the cooling is adequate.

Also monitor water consumption. Heat-stressed birds drink more water. If water consumption suddenly increases, it is a sign that the birds are trying to cool themselves. Check the water lines to make sure they are delivering enough water. A broiler at 90 degrees can drink twice as much as a broiler at 70 degrees. The water system must be able to meet this demand.

Common Mistakes and How to Avoid Them

The most common mistake is running the cooling system when the humidity is already high. This wastes water, raises the humidity in the house, and makes the birds more uncomfortable. Always check the humidity before turning on the cooling system. If the relative humidity is above 80 percent, the cooling system will not help.

A second common mistake is poor pad maintenance. Pads that are clogged with dust, algae, or mineral scale cannot absorb water or cool air. Clean the pads at the beginning of each flock and inspect them weekly. Replace pads that are damaged or show signs of deterioration. A pad that is 5 years old may look fine but cool at only 50 percent efficiency.

A third mistake is ignoring the static pressure. Pad systems increase the static pressure in the house, which reduces the airflow from the fans. If the static pressure is too high, the fans will move less air, and the cooling effect will be reduced. Check the static pressure regularly and clean the pads if the pressure rises above the design level.

A fourth mistake is placing fogger nozzles too close to the birds. Large droplets that fall on the birds can cause chilling, especially at night when the temperature drops. The droplets also wet the litter, which increases ammonia production and can lead to footpad lesions. Mount the nozzles high enough that the droplets evaporate before reaching the birds.

A fifth mistake is running the cooling system at night. The temperature often drops significantly at night, even during a heat wave. Running the cooling system when the temperature is below the set point wastes water and adds unnecessary moisture to the house. Use a controller that turns the system off when the temperature drops.

A sixth mistake is not having a backup plan. Pumps fail, nozzles clog, and power goes out. Have a spare pump, spare nozzles, and a generator on hand. Know how to switch to emergency cooling if the primary system fails. In a heat wave, a failed cooling system can kill a whole flock in a matter of hours.

Water Quality and Treatment

Water quality is the most overlooked factor in cooling system performance. Both pads and foggers are sensitive to minerals, algae, and biological growth. Poor water quality reduces cooling efficiency, increases maintenance, and shortens equipment life.

The first step is to test your water. A basic water test should measure pH, hardness, iron, manganese, and total dissolved solids. Hard water, with a calcium carbonate level above 150 parts per million, will leave scale on pads and in nozzles. Iron above 0.3 parts per million will stain pads and clog nozzles. Manganese above 0.05 parts per million has similar effects.

If your water is hard, install a water softener before the cooling system. A softener exchanges calcium and magnesium ions for sodium, which does not form scale. The softener should be sized to handle the peak water demand of the cooling system. If the water is very hard, you may need a larger softener or a reverse osmosis system.

Algae growth is a common problem in pad systems because the pads stay wet and the sump tank provides a place for algae to grow. Algae clogs the pad pores and reduces air flow. To control algae, use an algaecide that is approved for use in livestock drinking water. Copper sulfate and quaternary ammonium compounds are common choices. Follow the label directions and do not overdose, as the chemicals can harm the birds.

Bleed-off is another important practice. The bleed-off line removes a portion of the recirculated water and replaces it with fresh water. This prevents minerals from concentrating in the sump. The bleed-off rate should be adjusted based on the water hardness. For hard water, bleed off 20 percent of the recirculated water. For soft water, 10 percent is adequate.

Fogging systems require even cleaner water than pad systems because the nozzles have very small openings. A clogged nozzle stops fogging, which reduces cooling in that area. Install a 50 micron filter on the water line and clean it weekly. If the water has high mineral content, consider using a reverse osmosis system for the fogging water. The cost of the water treatment is offset by the reduced maintenance and longer nozzle life.

Recordkeeping and Performance Tracking

You cannot improve what you do not measure. Keep detailed records of your cooling system performance so you can make adjustments over time.

Record the following data daily during hot weather: outside temperature, outside humidity, house temperature, house humidity, static pressure, fan speed, cooling system run time, water consumption, and bird behavior. Record the data at the same time each day, preferably at the hottest part of the day. This gives you a consistent baseline for comparison.

Track pad condition weekly. Record the pad age, the water flow rate, and any signs of clogging or deterioration. Measure the static pressure across the pads. A rising static pressure indicates that the pads are becoming clogged. Clean or replace the pads when the static pressure rises by 20 percent above the baseline.

Track nozzle performance weekly. Count the number of nozzles that are not fogging. Clean or replace the nozzles that are clogged. Record the water pressure at the pump. A falling pressure indicates a clogged filter or a worn pump.

At the end of each flock, review the records. Calculate the total cooling system run time, the total water used, and the average house temperature during the hottest period. Compare these numbers across flocks. If you see a trend of increasing run time or water use, there may be a problem with the system. If you see a trend of increasing house temperature, the cooling capacity may be inadequate for the house.

Also track bird performance. Record the average body weight, feed conversion, and mortality for each flock. Compare the performance of flocks raised in hot weather with the performance of flocks raised in cool weather. This gives you a measure of the economic impact of heat stress. If the performance gap is large, consider upgrading the cooling system or changing the management strategy.

When to Call a Veterinarian or Extension Agent

Most cooling system problems are mechanical and can be solved by the grower. However, there are times when you need professional help.

Call a veterinarian if you see signs of respiratory distress that do not improve when the cooling system is running. Panting is normal in hot weather, but labored breathing, gasping, or coughing can indicate a respiratory disease. Heat stress weakens the immune system and makes birds more susceptible to infections. A veterinarian can diagnose the problem and recommend treatment.

Call a veterinarian if you see a sudden increase in mortality. Heat stress can kill birds quickly, but so can diseases such as avian influenza or Newcastle disease. If the mortality rate exceeds 1 percent in a day, or if you see birds with neurological signs such as twisted necks or tremors, contact a veterinarian immediately. These signs can indicate a reportable disease.

Call your extension agent if you are not sure how to size or install a cooling system. Extension agents have access to design tools and can help you calculate the cooling load for your house. They can also provide information on local climate conditions and recommended practices for your area.

Call your extension agent if you are considering a major upgrade to your cooling system. They can help you compare the costs and benefits of different systems and may know of cost-share programs or grants that can help with the expense.

Frequently Asked Questions

At what temperature should I turn on the evaporative cooling system?

The set point depends on bird age, humidity, and fan capacity. A common starting point is 85 degrees for birds over 3 weeks old. If the humidity is below 50 percent, you can start cooling at a slightly lower temperature. If the humidity is above 70 percent, wait until the temperature reaches 88 to 90 degrees. The goal is to keep the birds below 105 degrees body temperature. Check the birds regularly and adjust the set point based on their behavior.

Can I use both evaporative cooling pads and fogging in the same house?

Yes, some growers use both. The pads cool the incoming air, and the foggers provide additional cooling inside the house. This is most useful in very hot, dry climates where the pads alone cannot achieve the desired temperature. However, running both systems increases water use and the risk of wet litter. Start with one system and add the second only if the first cannot keep the birds comfortable.

How often should I clean the cooling pads?

Clean the pads at the beginning of each flock and inspect them weekly during hot weather. To clean a pad, turn off the water and let the pad dry. Then brush the surface gently to remove dust and debris. Use a mild detergent if the pad is dirty. Rinse thoroughly with clean water. Do not use a pressure washer, as it can damage the pad material. Replace pads that are damaged or have lost their rigidity.

What is the ideal air speed in a tunnel-ventilated broiler house?

The ideal air speed is 400 to 600 feet per minute at bird level. Higher air speeds create more wind chill, which helps the birds cool themselves. However, very high air speeds can cause the birds to huddle and reduce activity. Start with 400 feet per minute for young birds and increase to 600 feet per minute for birds over 4 weeks old. Measure the air speed at several locations in the house to ensure even distribution.

How much water does an evaporative cooling system use?

A pad system uses about 1 gallon of water per hour for every 10 square feet of pad area. A 400 square foot pad system would use about 40 gallons per hour. A fogging system uses about 1 gallon per hour for every 1,000 CFM of fan capacity. A 120,000 CFM house would use about 120 gallons per hour. These are estimates. Actual water use depends on temperature, humidity, and the system settings.

What should I do if the power goes out during a heat wave?

Have a backup generator that can run the fans and the cooling system. Test the generator monthly and keep it fueled. If the power goes out and the generator does not start, open the curtains or side walls to allow natural ventilation. Spray the birds with water using a hose or a sprinkler. Move birds to the coolest part of the house if possible. Monitor the birds closely and be prepared to remove dead birds quickly to prevent the spread of disease.

How do I know if my fogging nozzles are clogged?

Walk the house and look at each nozzle. A working nozzle produces a fine mist that evaporates quickly. A clogged nozzle produces a stream of water or nothing at all. Check the pressure gauge at the pump. If the pressure is higher than normal, the filter may be clogged. If the pressure is lower than normal, the pump may be worn or there may be a leak in the line. Clean the nozzles weekly and replace them when they cannot be cleaned.

Can I use well water for my cooling system?

Yes, but test the water first. Well water often has high mineral content, which can clog nozzles and reduce pad life. If the water is hard, install a softener. If the water has iron or manganese, install an iron filter. If the water has bacteria or algae, treat it with a sanitizer. The cost of water treatment is much lower than the cost of replacing pads and nozzles.

Related Farming Guides

This section will be populated with links to related broiler management and poultry housing guides after the article is published. Check back for updated content on ventilation system design, litter management, and heat stress prevention.

Related Clinical & Scientific Guides

References

FAO Poultry Production: https://www.fao.org/poultry-production-products/en/
USDA APHIS Poultry Health: https://www.aphis.usda.gov/livestock-poultry-disease/avian
WOAH Avian Influenza: https://www.woah.org/en/disease/avian-influenza/
FAO Animal Production and Health: https://www.fao.org/animal-production/en/
WOAH (World Organisation for Animal Health): https://www.woah.org/en/home/

This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.