Blog Post: Thinking About Manhole Aeration? Start Here.

1.    What Is Manhole Aeration?

Manhole aeration is a system installed through the existing manhole of a hopper-bottom grain bin. Instead of permanently modifying the bin or installing complex internal systems, the unit:

• Slides into the bin in two pieces

• Assembles inside

• Clamps securely to the manhole flange

• Connects to a fan via an air sock

The result? A simple, removable aeration solution that delivers airflow where it’s needed.

2.    What Size Bins Does It Work For?

Manhole aeration performs best in bins up to 5,000 bushels, but is still very effective in bins up to 8,000 bushels.  While it may take longer to cool larger bins, many farmers report strong airflow performance even at higher capacities.

3.    How Much Airflow Do You Actually Need?

A common misconception is that grain cooling requires high airflow. In reality, cooling grain only requires 0.1 CFM per bushel.  As an example, a 5,000 bushel bin needs a minimum of 500 CFM.  Of course, the higher the CFM, the quicker the grain will cool.  When paired with a 20 horsepower fan, Manhole Aeration can deliver airflows of up to 3000 cfm.   

4.    Fan Compatibility and Setup

Manhole Aeration can be connected to any fan brand using an air sock.  This allows many farmers to use existing equipment they already have on their farm.  Fans of 3hp to 20hp can be used.

5.    Installation and Handling

Ease of installation is a major benefit.  Here’s how it can be installed in 15 minutes or less:

• The cylinder comes in two parts.  Insert both parts into the bin through the Manhole.

• Assemble it inside the bin by connecting a few bolts. 

• Slide the cylinder into the manhole opening.

• Secured the cylinder in place using external locking tubes.

It’s designed for straightforward installation, even for a single operator.

6.    Durability Under Grain Pressure

A common concern is whether the system can handle the pressure of stored grain.  The thoughtful design reduces stress points and extends durability.  The angled design distributes force effectively and the cylinder’s location avoids the central grain flow during unloading.  Wavcor’s thorough testing and field experience has shown no structural issues. 

7.    Will It Cool Grain Evenly?

Short answer: No – but it pushes air through the bin, which is what is needed in order to cool grain.  Manhole aeration is about a practical way to get some airflow through the bin, which is always better than no airflow. 

8.    How Does It Compare to Other Aeration Systems?

Compared to the existing aeration systems on the market, Manhole Aeration:

• is lower cost

• requires no bin modifications

• installs quickly

• can easily be removed or moved to another bin

More advanced aeration ducting systems:

• are better for drying

• may provide more uniform airflow

• come at a higher cost and complexity

If your goal is cooling grain affordably, manhole aeration is a strong option.

9.    What are some special use cases for Manhole Aeration?

• Fertilizer Bins – because the cylinder can be easily removed when not needed, Manhole Aeration allows the bins to be dual purpose – used for grain storage in the fall and fertilizer storage in the spring. 

• Seed Bins – the Manhole Aeration cylinder is removable and easy to clean, which means that it reduces cross-contamination risk.