Air mixing fans — heat returns to where the birds are
Warm air rises to the ceiling on its own, while the litter stays cold and damp below. The gap between the top and the bottom of the hall can reach several degrees — and every one of them costs fuel. Air mixing fans push that heat back down, even out the temperature and dry the litter.
verifiedFrom the team that has organised work on poultry farms for years.
Air in a poultry house settles into layers by itself: warm air is lighter, so it travels up to the ceiling, while cold air sinks onto the litter. This is called temperature stratification. It bites hardest at the start and at night, when you are heating: you warm the hall, yet the most expensive heat gathers where there are no birds — under the roof. The chicks sit on cold, damp litter even though a thermometer high under the ceiling reads comfortable.
Why mix the air if I already have ventilation?
Ventilation exchanges air with the hall — it throws stale air out and lets fresh air in. Mixing fans do something else: they don’t expel air, they stir what is already inside, returning the warm layer from under the ceiling back down. The temperature then evens out from the floor to the roof, the litter dries, and the heater no longer has to overshoot. These are two cooperating jobs, not substitutes: minimum ventilation looks after fresh air, while mixing fans make sure the heat in it doesn’t escape to the ceiling.
How air is mixed in the hall
The choice depends on the volume, the height of the hall and how you run brooding and minimum ventilation.
Ceiling circulation fans
Mounted high, they blow horizontally and set the whole volume of the hall in motion. They create a gentle circulation under the roof that breaks up the layer of hot air and spreads heat evenly along the entire length of the house. The basic tool for fighting stratification.
Destratification fans (downward)
Aimed with their jet towards the floor, they push warm air from under the ceiling straight down to litter and bird level. They work locally where heat escapes most strongly to the roof. The key is to set them so they mix the air rather than blow a cold draught onto the chicks.
Positioning and jet angle
The fan itself is half the job — the rest is the direction and angle of the jet. The air should circulate around the hall and descend gently, not drop vertically onto the birds. At the start, when chicks are sensitive to air movement, the jet is aimed so it mixes the hall without a noticeable draught at litter level.
Working with ventilation and heating
Mixing fans work best wired into the same climate controller as minimum ventilation and heating. When the heater runs, the fans spread that heat through the hall instead of letting it escape to the ceiling. Tuned together they don’t fight each other but close the loop of warm air.
Drier litter and lower ammonia
Air movement near the floor evaporates moisture from the litter, which otherwise sits and cakes against the cold base. Dry litter means less ammonia, healthier feet and footpads and better welfare. This is one of the most important benefits of mixing, alongside the fuel saving itself.
Control by sensors and cycles
The most comes from control based on two sensors: one under the ceiling, one near the litter. The controller starts mixing when the gap between them grows, and it can run in cycles — a spell of mixing, a spell of pause. That way the fans only run when they are actually evening out the temperature.
Air mixing step by step
- 1
Measure the top–bottom temperature gap
Start with a diagnosis: measure the temperature under the ceiling and just above the litter at a few points in the hall. A gap of several degrees is clear stratification and a sign that heat is escaping to the roof. Measuring before and after will later show whether the fans are actually doing their job.
- 2
Size the number and output to the volume
The number and output of the fans are matched to the volume of the hall and to its length and height. The taller and longer the building, the stronger or more numerous the circulation needed to break the layer of hot air. Manufacturers give rough conversion figures — treat them as a starting point, not a certainty.
- 3
Position evenly and set the jet
Place the fans so their streams cover the whole length of the hall with no dead spots. Aim the jet so it circulates under the roof and descends gently — never straight onto the chicks. The goal is one calm circulation of air, not several competing swirls.
- 4
Run them especially at the start and at night
Mixing gives the most where you are heating: in the first days of brooding and on cold nights. That is when the top–bottom gap is largest and heat is most expensive. Once the birds grow and warm the hall themselves, tunnel ventilation gradually takes over the fans’ role.
- 5
Tune with minimum ventilation and the heater
Wire the fans into the controller together with minimum ventilation and heating so they act in concert. Mixing should spread the heat from the fresh air you let in, not blow it back outside. A well-tuned setup heats for shorter spells and more evenly.
- 6
Check the result: temperature and litter
After starting, check whether the top–bottom gap has shrunk and whether the litter near the floor has dried. Watch the birds too: evenly spread chicks and dry, friable litter are a sign that mixing works. If you see a draught or chicks huddled together, adjust the angle and the output.
Frequently asked questions about air mixing
What is temperature stratification and why does it harm?add
Stratification is air settling into layers: warm air gathers under the ceiling, cold air at the litter. It harms because the most expensive heat collects where there are no birds, while the chicks sit on cold, damp litter. You waste fuel and worsen the conditions at floor level — damp litter means more ammonia and poorer feet.
Won’t the fans blow the heat away and create a draught?add
No, if they are set up well. Mixing fans don’t expel air from the hall — they circulate what is already inside, so they don’t cool the building but rather recover heat from under the ceiling. A draught is a matter of jet angle and force: at the start it is aimed so it mixes the hall without any noticeable air movement at the chicks themselves.
How much fuel do mixing fans save?add
The saving comes from recovering the heat that escapes to the ceiling, so the heater runs for shorter and less often. The scale depends on the height of the hall, the insulation and how large the stratification was — the taller the building and the bigger the top–bottom gap, the more there is to recover. No exact figures can be promised in advance; it is best to measure the temperature gap and the consumption before and after.
How does a mixing fan differ from an exhaust fan?add
An exhaust fan exchanges air — it throws stale air out of the hall and draws fresh air in. A mixing fan expels nothing: it circulates the air inside, returning the warm layer from under the ceiling back down. These are two different jobs. The exhaust looks after air quality, the mixing fan after even heat — they work best together.
Describe your building’s equipment in DlaFerm.pl
In DlaFerm.pl, in the “Technical equipment of the building” step, you record how you ventilate and mix the air in the hall and what equipment you have — all in one place. Create a free account or write to us.
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