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Check pig barn ventilation before winter

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As we approach the coldest months of the year, it is worth ensuring that heating and ventilation systems in pig barns are set up correctly for the winter and routine maintenance is carried out.

During the spring, summer and fall, defects in the equipment may not be so obvious, because the effect on the pigs may be small. For example, a badly adjusted air inlet may not cause problems in warm weather, but when the air temperature drops, this can lead to cold drafts, which may cause discomfort and loss of performance. Another side effect of malfunctioning, badly calibrated or poorly maintained equipment is that it often leads to excessive energy use. With high fuel and power costs, this can make a difference of several dollars a pig.

Winter ventilation fans are critical because they have to provide the minimum air flow in the barn, thereby retaining heat, while still removing contaminant gases such as CO2 and H2S. If too much warm air is removed, the heaters have to work harder and energy is wasted. Therefore, calibrating the controller settings to achieve the correct minimum ventilation rate is the most important first step.

Venturi effect

At low ventilation rates, wind effects are a potential problem. The “Venturi effect” of wind passing over the building can literally suck air through roof mounted fans, giving 5 -10 times more air flow than required. This can be overcome by fitting dampers on the fans. Another potential source of over-ventilation by wind effect is through second-and third-stage fans which are not properly protected against leaks.

“Secondary fans should always be fitted with backdraft shutters,” says livestock environment specialist Ron MacDonald of Guelphbased Agviro Inc. “Fans, shutters and fan housings, both inside and outside the building, should also be washed each spring and fall.”

Air inlets determine the air flow pattern and must be set up correctly in order to obtain good air mixing and an even air temperature throughout the barn. In winter this is especially critical because if inlet openings are uneven, the temperature will vary between different parts of the barn.

“Inlets should be zeroed every spring and fall,” explains MacDonald. “This involves closing the inlet actuator manually and then adjusting all inlets so that they are fully closed. That ensures that, when they open, the inlet gaps will all be the same.”

It’s also important to check for and repair any broken or loose inlets, cables or clamps, he says.

Over the summer period, heating systems will not have been operating, except in nursery rooms, so heaters should be checked for correct starting and combustion in the fall.

“If heaters are adjustable, they should be set to minimum, unless it’s extremely cold,” MacDonald suggests. “In many cases, heating systems have a much higher output than is actually required.” Some heaters can be downsized by purchasing a smaller nozzle, he says, but this should be checked by contacting the manufacturer directly as local suppliers are unlikely to know whether this is possible.

Leakage points

MacDonald says air leakage is a major source of heat loss from buildings during winter. Typically there are leaks around inlets, fan shutters, doors, conduits and sometimes from manure pits, he says.

“Most buildings are like leaky sieves. By testing for leaks using smoke pencils and sealing them with a high-quality GE silicone, the problem can be solved.” Regular inspection of the joint sealant is also important due to the wear and tear from pressure washing, he says. Also, care should be taken not to get leakage of warm air into attics or short-circuiting of air between rooms.

During cold weather, condensation is a potential problem that can have devastating consequences.

“Moisture can get into the attic by a number of ways – leaks in the roof sheathing, and more likely, via moisture from the barn itself penetrating poor vapour barriers, through leaky and poorly sealed ceiling air inlets, and via exhaust air through the soffit openings,” says MacDonald.

“Moisture can quickly destroy just about any non-stainless, plastic or concrete component in a swine barn if left unchecked. Roof trusses and other roof components are likely to be attacked by moisture to some degree in all barns.” He advises that all attics and roofs should be inspected each spring and fall to ensure no damage has occurred and that the attic is not building up a moisture load.

“Owners can conduct a preliminary inspection, but any evidence of moisture that is not easily remedied should quickly be followed up with a call to a professional.”

The environment for newborn piglets is especially critical during winter and maintaining the correct temperature in the creep is essential. “You need to achieve 37C at birth and the only way to measure this is with an infrared thermometer,” MacDonald says.

“If it’s too cold, piglets move nearer the sow and this increases the risk of overlaying, but if it’s too hot they move away from the heat source and this also leads to more overlays.” He suggests that the temperature at piglet level is measured regularly and adjustments made manually to the heat level as piglets grow. Also, the room temperature needs to be stable in order to maintain a constant temperature in the creep area.

Proper preparation of heating and ventilation systems prior to the coldest time of the year will not only ensure the correct pig environment , resulting in optimum pig performance, but will also help to minimize energy costs.

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