Winter is knocking on your swine facility's door. So it’s wise to be ready.

When dealing with winter and cold-weather operation several problems can occur if you ignore the ventilation system or proper maintenance tasks. Some of those include higher than necessary energy bills, poor air quality, humidity levels that are too high or too low, cold-air drafts, disease outbreaks and, ultimately, poor pig performance. 

For example, by resetting the ventilation control from a very tight setting to letting the controller do its thing, a producer with a 2,000-sow, farrow-to-feeder pig operation that finished out one-third of his pigs reduced his propane bill from $97,000 in 2006 to $40,000 in 2007. This cost reduction occurred even with higher propane costs and a colder winter. 

So, where should you direct your attention before Mother Nature really turns cold? Key areas that need attention now include the following items and procedures:

Fans: Dirty fans (those with 1/8 inch of dust) can reduce airflow up to 40 percent, and cleaning fans means all fans. The accompanying photo shows a pit fan that hasn’t been cleaned in five years.

Having poor-performing fans will raise electrical costs because more fans will need to run to compensate for the lack of ventilation. This could lead to poor air quality and increased humidity due to the reduced airflow. 

Here’s what you need to do:

  • Clean fan blades and shutters.
  • Ensure that deflectors and cones are in good repair.
  • Correct the tension on belts.
  • Have winter covers on-hand for any unused fans. 

Even though this is a winter checklist, you should inspect fans every month. 

Air inlets: Air inlets are critical for proper air distribution in a swine facility. Common problems that occur include not having enough openings for the required airflow, downdrafts caused by having opposing airstreams too close to each other, and either operating at static pressure that is too low or too high. See the accompanying graph for operating inlet air speeds and static pressures.  

Here’s what you need to do:

  • See that inlets are in good working order.
  • Inlets should open uniformly throughout the facility.
  • Inlets should have counter-weighted baffles allowing for 4 inches of air movement and not be locked down completely.   

Also, all pump ports and all other unplanned openings (holes in curtains) need to be sealed for air inlets to operate correctly. 

Soffits: For air inlets to operate properly, you will need to clean soffits of all debris. It's also a good time to make sure soffits are allowing enough airflow into the attic space. Soffit-net-free area is defined as a minimum of 3/4-inch by 3/4-inch opening, with the amount of airflow being pulled through at a maximum rate of 400 cubic feet per minute per 1 square foot of soffit opening. 

For example, if 50,000 cfm of airflow is being pulled through the attic to the inlets, the soffit opening would need to be 125 square feet. The accompanying photo shows an example of correct soffit construction.

Curtains: Curtain leakage is a major problem with negative-pressure ventilation systems and ceiling inlets. If curtains aren’t tight, air enters from the curtain versus the ceiling inlets and air distribution is a problem. Also, having small cracks around the curtain can lead to excessive propane use. 

Here’s what you need to do:

  • Ensure that the curtain has no sags or gaps.
  • It should have a 2- to 3-inch overlap at the top plate.
  • Repair all holes (anything greater than 1/2 inch by 1/2 inch).
  • Ensure that ropes are in place and tight.
  • It should move 2 to 4 inches per cycle.
  • Repair end-pockets.

Misters: For misters, make sure the solenoids and water lines are turned off.

Furnaces: Clean them and light the pilot lights. If the heater is a variable-output model and oversized at maximum output (especially with large pigs in the room), it may be beneficial to turn the output down.  It's easier to maintain a uniform temperature if heaters run longer rather than in short bursts.    

Controllers: You can benefit from reduced heating costs if there's a thorough understanding of controller settings and how they affect the overall ventilation system. A common problem is heat that overshoots the set-point temperature and variable-speed fans that ramp up to compensate for the increase in room temperature. This is caused by not shutting the heater off quickly enough when the room’s temperature reaches the set point and/or having the variable-speed fan bandwidth set too tight. The bandwidth on cold-weather, variable-speed fans should be set no tighter than 1.5° F, preferably 2° F, and the furnace offset temperature set from 1° F to 2° F. If the heater is oversized, the offset temperature may need to be increased. 

Also, the minimum speed setting on variable-speed fans may be set too high, causing over-ventilation and wasting heat. If there are two variable-speed fans on the circuit, it may be better to shut one off and run the other at a higher speed, until pigs are larger and more airflow is required. 

Emergency thermostats: The high temperature should be set at 90° F and the low temperature set at 60° F.

Temperature probes: You should clean temperature probes and check for accuracy. Since controllers use the average of all the probes, having even one defective probe will effect the overall ventilation performance. Also, place probes so that the recorded temperature reflects the pig space. It should not be in a position where hot air from a heater or cold air from an inlet affects the readings.  

The temperatures will only get colder and your energy bills will only push higher if you ignore these tasks now.


Finding The Optimum Range

A common problem that occurs with air inlets involves operating at static pressure levels that  are too low or too high. Shown here is the relationship between air-intake velocity and static pressure. Note the best range of operation.