Top VS Side Opening Beer Fermenters: Key Differences, Advantages And How To Choose

In modern breweries, fermentation tanks are one of the most important pieces of equipment. The design of a fermenter directly affects production efficiency, sanitation, maintenance, and overall brewing workflow. Among the many design features of a fermentation tank, the location of the manway (access door)—either on the top or on the side—is a key structural difference that brewers must consider.

Both top-opening fermenters and side-opening fermenters are widely used in the brewing industry. Each design has its own advantages depending on brewery size, production process, and operational preferences. Understanding the differences between these two configurations can help brewers select the most suitable fermentation equipment for their brewery.

What Is a Fermenter Manway?

A manway is essentially the access door of a fermentation tank. It allows brewers or technicians to inspect, clean, and maintain the interior of the vessel. In modern brewing systems, fermenters are usually cleaned using CIP (Clean-in-Place) systems, but manways are still essential for manual inspection, maintenance, or adding ingredients when required.

The position of the manway generally falls into two main categories:

• Top-opening manway fermenters

• Side-opening manway fermenters

Although both designs serve the same fundamental purpose, their practical applications and operational convenience differ significantly.

Top Opening Fermenters

Top-opening fermenters feature a manway installed on the upper part of the tank. This design is commonly found in larger fermentation vessels used in commercial breweries.

Advantages of Top Manway Fermenters

1. Better internal access for maintenance
Top manways provide a large opening that allows easier access to the interior of the fermenter. This can be useful for deep inspection, maintenance, or equipment adjustments.

2. Improved hygiene and smoother tank surface
Without a side opening, the cylindrical wall of the tank remains smoother, reducing potential areas where bacteria or residue could accumulate.

3. Easier ingredient addition from above
Some brewing processes require the addition of hops, yeast, or other ingredients during fermentation. A top opening allows these ingredients to be added directly into the tank.

Disadvantages of Top Manway Fermenters

1. Requires ladders or platforms
Because the manway is located at the top of the vessel, operators often need ladders, catwalks, or platforms to access it safely.

2. Potential safety concerns
Frequent climbing can increase safety risks if proper access systems are not installed.

Side Opening Fermenters

Side-opening fermenters feature a manway located on the side wall of the tank, typically positioned at a convenient height for operators.

Advantages of Side Manway Fermenters

1. Easier access from ground level
Side manways allow operators to inspect or access the tank without climbing ladders, making daily operations safer and more convenient.

2. Ideal for smaller fermentation tanks
For smaller vessels, the top dome area may not provide enough space for a manway. In these cases, a side manway is often more practical.

3. Improved visibility during inspection
Side access allows brewers to easily look inside the tank during cleaning or inspection processes.

Disadvantages of Side Manway Fermenters

1. Potential leakage risk
If a side manway seal is not properly secured, liquid pressure inside the tank could cause minor leakage during operation.

2. Cleaning challenges
Side openings may create areas where cleaning spray patterns from CIP systems are less effective, requiring careful inspection after cleaning.

Choosing the Right Fermenter Design

When deciding between a top-opening or side-opening fermenter, brewers should consider several practical factors.

1. Tank Size

A common rule in the brewing industry is:

• Small fermenters (1000L or below): side manway preferred

• Large fermenters (2000L or above): top manway often used

This is mainly due to space limitations and ease of access.

2. Brewery Layout

The physical layout of the brewery plays an important role. Breweries with catwalk platforms may find top manways more convenient, while smaller breweries without elevated access may prefer side openings.

3. Brewing Process

Certain brewing techniques, such as dry hopping, may benefit from top access. However, many modern fermenters now include dedicated hop ports that make both configurations equally practical.

4. Cleaning and Maintenance

Although CIP systems handle most cleaning tasks, breweries should still ensure that fermenters can be easily inspected and maintained.

Which Fermenter Type Is Better?

There is no universal answer to whether top-opening or side-opening fermenters are better. Both designs are widely used across breweries worldwide.

In general:

• Top manways are often preferred for large industrial fermentation tanks and breweries with elevated platforms.

• Side manways are commonly used for smaller tanks and breweries that prioritize easy access from ground level.

Ultimately, the best choice depends on the brewery’s equipment layout, production scale, and operational preferences.

Conclusion

The position of a fermenter manway may seem like a small design detail, but it can significantly impact the daily operation of a brewery. Top-opening fermenters provide excellent internal access and are often used in larger brewing systems, while side-opening fermenters offer convenient ground-level access and are well suited for smaller tanks.

When selecting fermentation equipment, brewers should evaluate their production capacity, available space, cleaning procedures, and safety considerations. By choosing the right fermenter configuration, breweries can improve operational efficiency and maintain consistent beer quality.

As craft brewing continues to grow worldwide, modern fermentation tank designs are becoming more flexible, allowing breweries to customize equipment according to their specific brewing needs.