About Us

We are producers just like you, and we have been designing and managing ventilation systems for the past 39 years. At Tunnel Plus, we apply our understanding of elite design and barn operations to give you the system you can count on for years to come – done the right way, the first time and made easy to operate.

Our Mission

Our Mission is to engineer the ideal climate for your facility focusing on our design of 4-season ventilation and cooling systems

Our Story

Tunnel Plus Story

Tunnel Plus was started in 2012 as a division of Hershey Ag where “superior production systems” are a way of life. 

In Hershey Ag’s 40+ years in the swine industry, we have witnessed the transition to power ventilated barns which has led to healthier animals and higher production levels. Hershey Ag’s 40+ years of experience in the design, construction oversite and management of over 50 sow and piglet grow-out barns laid the groundwork for creating systems to “engineer the ideal climate” in dairy barns.

Why ventilation?  From piglets to market, the ventilation demands of the pigs are constantly changing.  We are continually adjusting and fine-tuning the ventilation systems to keep pigs healthy and growing. Not only can we design systems tailored to your needs, we also understand how to manage the systems.

Our extensive experience in livestock cooling and ventilation, coupled with our personal roles in livestock production, allows us to understand the needs of dairy producers who are seeking to provide “4-season ventilation and cooling” to diminish heat stress, ensure consistent milk production, decreased pregnancy loss, and enhanced milk components.

Our custom designed systems will meet the dairy industry’s highest standards for efficiency, herd health and ease of operation.  

At Tunnel Plus, our team applies our understanding of superior design and barn operations to give you the system you can count on for years to come – done the right way, the first time and easy to operate.


Stop your losses, call us today and get a Tunnel Plus system to fit your needs.

Who We Are

For Farmers, by farmers

Our team’s years of experience and expertise in livestock cooling and ventilation needs, plus our personal roles as livestock producers, allow us to relate to the needs of dairy producers.

At Tunnel Plus, we not only design and create systems tailored to your needs, we also understand how to manage systems. Our design and automation standards make running your system easy, flexible, and worry free.

Jeff Grandner

Jeff Grandner is the General Manager for Tunnel Plus, Four Season Ventilation and Cooling. 

He has worked with agricultural ventilation systems for 30 years, starting out his career as a hog truck driver in 1992, then working as a Grow Out Specialist for Hershey Ag for 19 years.  While servicing hog grow out barns, Jeff developed a level of expertise in computerized ventilation systems, one of the key elements to all animal production.  He learned to manage ventilation for the greatest growth potential in the most efficient manner.  

In 2014, Jeff became a part of the newly formed Tunnel Plus division of Hershey Ag.  Jeff wears many hats in Tunnel Plus including consultant, system design, purchasing, installation coordinator, sales, and technical support.  While Jeff continues to design fan systems for hog operations, he has developed a passion for the dairy industry.  He works with dairy producers to custom design the best possible ventilation systems for maximum production results. 

With Jeff’s extensive ag background, he is a key leader in Tunnel Plus and finds great satisfaction in designing, implementing and monitoring the positive results of Tunnel Plus custom designed systems.

Brent Hershey

Brent Hershey is the owner of Tunnel Plus, Four Season Ventilation and Cooling.  

 Brent grew up on a poultry farm working with negative pressure poultry housing.  In 1981, he started Hershey Ag and entered the hog production business.  He introduced the first tunnel ventilated hog barn in Pennsylvania in 1992.  Today, all the facilities in Hershey Ag’s swine production system are tunnel ventilated, providing the optimal climate year-round.

In 2012, after 30 years in the hog industry, Brent started the Tunnel Plus division of Hershey Ag, a ventilation business specializing in dairy barns.  He saw the dairy industry moving to enclosed power ventilated barns and seeking optimal milk production. 

The many years of experience in the swine business laid the foundation for successful planning, design, installation and operation of dairy barn systems.  Today, Brent leads the Tunnel Plus team in “engineering the ideal climate” in holding areas, calf barns and dairy operations throughout the northeast and Midwest.  


Why Choose Us?

We have designed and installed more than 250 dairy ventilation systems in 17 states, engineering the ideal climate for thousands of cows.  Our fully automated systems help reduce heat stress and improve animal comfort, ultimately resulting in increased reproduction, and increased milk production.  Whether it’s in your holding pen, over the freestalls, over the bedded pack or in your calf barn, we design a system around what you and your cows need!