Poultry house static pressure explained: what it is and how to manage it
Poultry house static pressure explained for tunnel and minimum ventilation: what the reading means, how to measure it.
Static pressure is the small difference in air pressure between the inside and the outside of a closed poultry house while the exhaust fans run. The fans pull air out, so the house sits slightly below outside pressure, and fresh air is drawn in through the planned openings: the cooling-pad inlet in tunnel mode, or the side-wall and ceiling inlets in minimum ventilation. This guide explains what the reading means, how to check it, and how it affects the equipment you specify.
What the static pressure reading tells you
Think of the reading as the resistance the fans must work against. Every part of the air path adds some: the pad face, the inlet openings, the house itself, light traps and shutters at the fan wall. A low reading in a tight house with fans running usually means air enters easily through the intended inlets. A reading that climbs over time often points to a restriction, such as dirty pads, blocked traps or shutters that no longer open fully.
The reading is not a target on its own. It only makes sense together with the air speed you want and the airflow the fans deliver at that pressure. Our guide on how many exhaust fans a tunnel house needs gives a common tunnel-mode band for many houses of about 10 to 30 Pa (0.04–0.12 in. water column). Your integrator or ventilation designer sets the working range for your house.
How to measure static pressure in a poultry house
Static pressure is read with a manometer or the pressure sensor on the house controller. A simple routine:
- Run the house in its normal mode with doors and unused openings closed.
- Place the outside reference tube where wind cannot blow straight into it.
- Note the reading in tunnel mode and again in minimum ventilation, with the pads wet and dry if you can.
- Repeat at the same points each season, and write the readings down so changes are visible.
A sudden change between checks is more useful than a single number. It tells you something in the air path has changed.
What raises static pressure
- Cooling pads: wet pads resist airflow more than dry ones, and finer flutes or thicker packs generally add resistance. Pad thickness on this site is offered in 100, 150 or 200 mm, as quoted.
- Light traps on dark-out houses: the baffled air path adds resistance at the fan wall.
- Dirty or sticking shutters, dust on fan guards and slipping belts.
- Inlet area that is too small for the fan capacity in use.
Static pressure in broiler and layer houses
Broiler houses in hot weather usually run long periods in tunnel mode with wet pads, so pad condition and fan output at working pressure matter most. Layer and breeder houses are often dark-out, which adds light traps to the air path. In both cases the same rule applies: fans are chosen for the airflow they deliver at the pressure the house will run at, not their free-air figure.
Static pressure vs airflow: why fans, pads and traps are quoted together
As pressure rises, any exhaust fan moves less air. That is why EcoHarvest quotes a tunnel ventilation system as one design. On the exhaust fans page, Box, Hammer-shutter and Cone models are listed with catalogue airflow in m³/h only; that page says no laboratory pressure tables are published. Airflow and power for your opening and working pressure are confirmed on the written quotation.
When you ask for a quote, send house size, livestock and stocking, pad and light-trap plans, voltage and frequency, and any pressure readings you already have.