Ask the Expert: What Maintenance Does My PPTV Need? – Courtney Halbach, The Dairyland Initiative
By Courtney Halbach, associate outreach specialist, The Dairyland Initiative
Question: What maintenance does my positive pressure tube ventilation system need to continue working efficiently?
Answer: Positive pressure tube ventilation (PPTV) systems have significantly improved calf health and air quality in many calf barns by delivering fresh, outside air at the minimum ventilation rate of four air changes per hour without creating a draft. In order to perform as expected, PPTV systems need to be maintained properly.
When maintained properly, we expect the PPTV fan to operate constantly for about five years before performance declines. Even if the system appears to be running normally after five years, we can measure some deterioration of fan performance. The lifespan of a fan varies by company, so you will want to check with the fan manufacturer to determine the average lifespan of the fan and follow the suggested maintenance by the company to ensure that you maximize the fan’s lifetime. After the system has been running continuously for five years, confirm with a trained PPTV designer that the system is up-to-date with the latest recommendations.
Just like any other fan on the farm, the fan in the PPTV system needs to be cleaned routinely, preferably at the beginning of each season. Before cleaning, turn off the system’s breaker or switch to avoid accidental powering and risk of injury. Once the system is off, remove all dirt and dust build-up from the fan blades, fan housing, weather hood, and tube using a brush, vacuum or small blower. If the fan is belt-driven, check the belt alignment and tension, and replace any worn belts.
The opening of the weather hood can often be blocked by garbage or debris, decreasing the air intake area and stressing the fan (see photo 1 below). This reduces the amount of air entering the PPTV system. Taking time to check if anything is obstructing the weather hood opening can help preserve the efficiency of the fan.
Having an oversized weather hood that allows air to travel through the hood opening at 500 feet per minute can reduce the likelihood of drawing snow or rain into the tube system. If the fan is installed close to the roof with the bottom of the hood within 5 feet of the roof, adding an extension to the hood may eliminate snow or rain from entering the tube.
Some warmer-weather PPTV systems are thermostatically controlled. If this is the case, use a reliable thermometer to compare the thermostat to the inside temperature of the barn. The thermostat should be installed out of the sun and toward the middle of the barn for the most representative reading of the calf environment.
Lastly, verify that the wiring to and from the fan is not exposed or damaged, and that the fan components and housing are securely bolted and fastened.
Properly maintaining the components of a PPTV system can ensure maximum efficiency, performance and lifespan of the system. More information about PPTV systems and a list of certified consultants for PPTV design in youngstock housing can be found on The Dairyland Initiative website.
Photo 1 (left). Debris blocking the weather hood opening limits air intake and minimizes fan performance.
Photo 2 (right). A hood extension on the north side of a building can reduce the pickup of snow and rain.
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