The recent spike in propane prices is additional incentive for swine producers to conserve heating energy. Pork producers may have propane contracted at a reasonable rate, but managing heating costs should always be a priority, especially when expenses rise.
"Often the first idea for saving heating fuel in hog buildings is to add insulation," said Jay Harmon, professor in Agricultural and Biosystems Engineering at Iowa State University. "However, ventilation management should actually come first because more than 80 percent of the heat loss in a swine building is due to improper ventilation."
Proper ventilation rate
The goal during colder months is to control moisture and ammonia as much as possible. Underventilating a building results in poor air quality and may cause health and growth problems with pigs. Conversely, overventilating by just 20 percent can increase propane usage by 50 percent. In some cases, especially in wean-to-finish buildings, minimum ventilation fans may be too large, too many fans may be used, or the percent speed setting may be too high. If overventilation occurs and you are using two fans for minimum ventilation, try turning off one fan and running the remaining fan at a higher speed.
Monitor air quality to be sure you are providing enough air. The percentage shown in the controller is likely not the percentage of fan capacity so it may take time to find the appropriate setting.
Adjust the temperature
The proper temperature is important for energy efficiency. Observe the pigs to determine their comfort level. If pigs are too cold, they will huddle and pile up when resting. If they're too warm, they will avoid each other. Adjust the temperature (figure 1) so pigs sleep side by side but not in a pile. A few degrees difference can save a substantial amount of propane.
Adjust the heater
The controller should be adjusted (figure 1) so that minimum ventilation fan speed never increases while the heater is cycling. If the heater runs and then shuts down and you can hear a fan increase its speed, it means that the heater is shutting off too close to the setpoint. If you hear this happening, simply adjust the heater to shut off at a slightly lower temperature. In the case of one producer, it was documented that setting the heater to shut off one-half degree lower saved 3.75 gallons of liquefied petroleum per furnace per day.
"Another way to save propane is by reducing the heat output of your direct fired heater by turning the 'blue value' on your existing heaters (figure 2) to an approximate 60 percent output," said Larry Jacobson, University of Minnesota professor and Extension engineer. "Although it seems counterintuitive, a smaller heater will run longer and use less propane compared to a large, often oversized heater. Plus, they provide smaller variation in room temperatures."
Adjust the ventilation when using brooders
Some producers use brooders for small pigs. This allows producers to keep the room cool, but the pigs feel warmer due to localized heating. If the setpoint is low--70 degrees, for instance--extra fans may switch on to maintain this cool temperature in the room. A better approach is to set the room setpoint just above the brooder temperature--85 degrees, for example--but to have your heater turn off at a lower temperature, such as 70 degrees. By preventing fans from cycling too early, this technique retains more heat in the building rather than discarding it through the ventilation system.
Air leaks such as holes in ventilation curtains, leaky fan louvers or cracks around doors may create cold spots which cause heaters to run longer than necessary. Eliminate these and other leaks to maintain air quality and to reduce propane consumption.
Jacobson and extension engineers from Iowa State University, South Dakota State University and University of Nebraska have organized ventilation workshops for pig barn managers and those dealing with the environmental operation of barns. The group has a modified trailer equipped with fans, inlets and controllers that demonstrates ventilation and heating principles. Full-day workshops can be scheduled for your producer group or client base by contacting Jacobson at firstname.lastname@example.org.
Information originally prepared by Jay Harmon and Dana Schweitzer of Iowa State University Extension and Outreach with additional information by Larry Jacobson, an agricultural engineer with the University of Minnesota Extension.