Last updated: August 11, 2021

Welcome to our big centrifugal fan test 2021. Here we present all the centrifugal fans we have tested in detail. We have compiled detailed background information and added a summary of customer reviews on the web. We would like to make your purchase decision easier and help you find the best centrifugal fan for you. You will also find answers to frequently asked questions in our guide. If available, we also offer interesting test videos. Furthermore, you will also find some important information on this page that you should definitely pay attention to if you want to buy a centrifugal fan.




The most important facts

  • Centrifugal force allows centrifugal fans to generate high airflows and work against high resistance.
  • Centrifugal fans with backward curved blades have the highest energy efficiency.
  • Centrifugal fans with forward curved blades are the quietest, so they are particularly suitable for office or home use.

The Best Radial Fan: Guide and Recommendations

Guide: Questions you should ask yourself before buying a centrifugal fan

What is a centrifugal fan?

Centrifugal fans are helical fans that can draw in and expel air at high pressure. They are mainly used for industrial and commercial applications.

A centrifugal fan can be used as a ventilation system of rooms and blow the bad air even through long ventilation shafts. (Image source: 123rf.com / 89589115)

They can also be used in the home in the bathroom or kitchen. However, since they require some space to draw in the air and have to be installed, they are rarely used in private homes. Due to their worm shape, they suck in the air from the sides of the housing and expel it at a 90º angle towards the head.

What do I need a centrifugal fan for?

Centrifugal fans are characterised by high pressure. This means that they can suck in air with a high force and expel it in a different direction.

This high pressure is needed in some areas of industry and commerce to ventilate rooms.

The high pressure allows centrifugal fans to suck bad air out of the room and direct it even through long ventilation shafts. On an outside wall, it can also guide the air directly outside. In industrial processes that produce certain gases, the gases can be diverted in this way. Centrifugal fans are also used as extractor bonnets in restaurant kitchens. In general, even in private use, cooker bonnets usually contain a centrifugal fan, which is encased in a housing and diverts the air.

How does a radial fan work?

Centrifugal fans primarily use centrifugal force. A motor first drives blades inside the centrifugal fan. These can be straight, forward or backward curved.

The curvature of the blades determines the characteristics of the fan

First, air enters an impeller (yellow in the picture) in the volute casing (white in the picture) via the side and is accelerated here by the motor and centrifugal force. Then the air is discharged at a 90º angle. The air flow can be increased by placing several radial fans next to each other. This way, they all suck in the air from one direction, creating a larger flow.

What are the alternatives to the centrifugal fan?

An axial fan is often considered as an alternative to the centrifugal fan. This can suck in large amounts of air, but only with little resistance or force. The axial fan has large propellers that suck in and expel the air axially. This means that they draw the air in from one direction and expel it in the opposite direction. Due to their simple and space-saving design, axial fans are suitable for ventilating large halls. However, they are not suitable for diverting gases under high pressure. In addition, axial fans produce more noise and are therefore not suitable for open-plan offices or other places where quiet products are required. Centrifugal fans are much quieter in comparison. In smaller rooms, a pedestal fan is usually sufficient to create a pleasant air climate.

Decision: What types of centrifugal fan are there and which is the right one for you?

If you are thinking about buying a centrifugal fan, you can essentially distinguish between three models:

  • Centrifugal fans with forward curved blades
  • Centrifugal fans with straight blades
  • Centrifugal fans with backward curved blades

In the following table you will find an overview of the different characteristics of centrifugal fans:

Centrifugal fan with forward curved blades Centrifugal fan with straight blades Centrifugal fan with backward curved blades
Impeller size at the same air flow rate Small Very large Large
Speed at the same air flow rate Low Very high High
Dirt-prone Yes No Yes
Best efficiency At low pressure At low pressure At high pressure
Stability at too high air flows Medium Medium High
Energy efficiency Medium Low High

What are the characteristics of a centrifugal fan with forward curved blades and what are their advantages and disadvantages?

As we have already explained, one of the most important parts of the centrifugal fan are the blades. For various reasons, they are curved differently. With forward curved blades, the same air flow and pressure parameters can be achieved as with backward curved blades. Centrifugal fans with forward curved blades achieve this with a smaller impeller diameter than centrifugal fans with backward curved blades. Therefore, they save more space.

Advantages
  • Quieter than the other types
  • Suitable for low pressure applications
  • Achieve the same ratios with smaller impeller and lower speed
Disadvantages
  • Consume more power
  • Not suitable for high pressure applications
  • Have lower efficiencies

For the same air flow rate, backward curved blades are more energy efficient and can work against higher resistance. Therefore, centrifugal fans with forward curved blades are only used for purposes where there is relatively low resistance from the intake side and quiet operation is important.

What distinguishes a centrifugal fan with straight blades and what are its advantages and disadvantages?

When using centrifugal fans with straight blades, debris rather than gases are extracted. They are available with open and closed impellers.

Advantages
  • Contaminants do not stick to blades
  • Suitable for diverting debris
  • Used mainly in agriculture
Disadvantages
  • Do not achieve high efficiencies
  • Consume more electricity
  • Too inefficient for clean gas extraction

Therefore, they are mainly used in agriculture for the extraction of grain or wood chips. Here, the caking of the extracted material on the straight blades can be avoided.

What distinguishes a centrifugal fan with backward curved blades and what are their advantages and disadvantages?

When comparing the operation of centrifugal fans with forward versus backward curved blades at the same air performance, the backward curved blades are more efficient.

Advantages
  • Achieves the highest efficiencies
  • Suitable for high pressure/resistance applications
  • Are more energy efficient
Disadvantages
  • Noisier than other types
  • Take up more space as they require larger impellers
  • Need high speeds for adequate performance

Centrifugal fans with backward curved blades are therefore more likely to be used when space is at a premium and noise is not an issue. Even at high air flows, backward curved blades do not overload too quickly. They are mainly used with high resistance from the intake side.

Purchase criteria: You can use these factors to compare and evaluate centrifugal fans

In the following, we would like to show you which factors you can use to compare and evaluate centrifugal fans. This will make it easier for you to decide whether a certain centrifugal fan is suitable for you or not. In summary, these are:

  • Area of application
  • Air performance
  • Power consumption
  • Loudness
  • Size
  • Required amperage

Application area

Centrifugal fans are used in many applications to divert gases or materials. Each type is suitable for specific applications. For industrial processes with hot temperatures, the manufacturers should advise on the purchase. Hot temperatures can overload motors. Therefore, they should be mounted outside the enclosure and additionally cooled if necessary. Also, when extracting special gases, the manufacturers should be contacted as to whether the materials of the centrifugal fan are suitable for this.

In industry, centrifugal fans are often used to divert gases, some of which are toxic. Therefore, more than just the air performance must be taken into account in this area. (Image source: 123rf.com / 90309584)

For private use, in open-plan offices or in the kitchen, centrifugal fans with forward-curved blades are more suitable, as quiet products are needed here.

The most common applications in the private sector are centrifugal fans as extractor bonnets or as bathroom fans.

When extracting materials that can stick to the blades, centrifugal fans with straight blades should be used. This is why they are often used in agriculture.

Air output

The required air performance also depends on the area of application. For a vacuum, particularly powerful products with an air flow rate of over 2,500 m³/h are required. The air output is indicated on each product in m³/h. This is achieved with the different types of centrifugal fans with different speeds. Centrifugal fans with a low speed produce quieter operating noise. This is the case with centrifugal fans with forward curved blades.

Power consumption

Power consumption may also be an important purchase criterion for environmental and economic reasons. The power consumption of centrifugal fans is given in kWh.

Since centrifugal fans are often used for a very long time, energy-efficient devices are usually much more cost-effective. (Image source: pixabay.com / geralt)

The power consumption depends, among other things, on the air performance, i.e. the strength of the centrifugal fan. Centrifugal fans with backward curved blades consume 20% less electricity for the same air performance.

Volume

For many applications, the centrifugal fan should be as quiet as possible. In this case, centrifugal fans with forward curved blades are recommended because they have a lower speed. Large centrifugal fans with higher air output produce more noise. Therefore, you should think carefully about the size of the centrifugal fan and its air output.

Size

The previous paragraph already gives a first reason why you should choose a rather small product if you prefer a quiet centrifugal fan. Another reason is, of course, the space you need to install the unit. You should also consider whether the fan leads directly to the outside or into an air shaft. Centrifugal fans discharge the air at a 90º angle into a spiral housing. This housing must be mounted either in an outside wall or on a ventilation shaft.

The 90º angle can make it more difficult to find a suitable place for the centrifugal fan.

Before purchasing, it should be considered whether a single or double inlet centrifugal fan makes sense for the given space conditions.

Required amperage

Most centrifugal fans can be connected to a conventional 230V socket. However, there are some powerful centrifugal fans that require a heavy current source.

Facts worth knowing about centrifugal fans

How do you install a centrifugal fan?

When installing centrifugal fans, care should be taken to align the intake side appropriately. Since there are single- and double-sided intake centrifugal fans, this should be considered before buying. For centrifugal fans, the angle must also be taken into account. Installation in an exterior wall may require a core drilling, which should be carried out by a specialist. In the private sector, you will probably install a centrifugal fan in the form of a bathroom fan, as a ventilation system or as an extractor bonnet in the kitchen. You can find installation instructions for a bathroom fan here:

How do you clean a centrifugal fan?

Cleaning centrifugal fans may be necessary from time to time, especially in ventilation systems. However, this can be a somewhat laborious process. Therefore, we would like to show you all the steps here. To clean the centrifugal fan, you must now proceed as follows:

  1. Switch off the voltage source of the centrifugal fan and secure it against being switched on again.
  2. If present, dismantle the control terminal.
  3. Place the centrifugal fan on the sealing bonnet.
  4. Remove the protective grille and the suction ring.
  5. The impeller can now be removed if the impeller lock has been removed beforehand.
  6. Now you can clean the impeller and housing with a cloth and some cleaning agent.
  7. Reassemble the centrifugal fan.

However, not every centrifugal fan should be cleaned and disassembled. Doing so may cause the fan to lose its tightness and affect its performance.

How do you store a centrifugal fan?

Since centrifugal fans are at risk of corrosion if stored poorly, they should always be stored in their packaging. The centrifugal fan should be stored in a dry place.

Corrosion and rust can cause the units to lose efficiency or even break.

How can I build a centrifugal fan myself?

In principle, you can build a centrifugal fan yourself. You should not expect a particularly powerful performance. Nevertheless, you can use your own centrifugal fan for private ventilation. You will need the following materials to build your own centrifugal fan:

  • Cardboard
  • Glue
  • A small motor
  • A ball bearing
  • A short wooden stick
  • Batteries or other power source

You can find detailed instructions on how to build your own centrifugal fan in this video:

Image source: 123rf.com / 89589115

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