5 Reasons Why Your Commercial Kitchen Hood Doesn’t Work Properly (With Pictures)

As a commercial kitchen designer, one of the most common problems I have witnessed among all kitchen owners and managers is problems related to the exhaust hood, ignoring the simplest and most basic problems such as a malfunction of the extractor.

This is understandable, since the exhaust hood in a commercial kitchen, like the cooking equipment, is like the heart of the kitchen, it is a piece of equipment that has to be working and working for extended periods of time without stopping.

Among all the cases I have noticed, the most common reasons for exhaust hood problems in commercial kitchens are due to three factors:

• poor exhaust hood design
• poor exhaust hood installation
• poor exhaust hood maintenance

Of these three factors, each one has a different responsibility, usually, the design of the hood is done by one person and the installation is done by another, they are independent tasks.

The maintenance of the exhaust hood is the only factor that is the responsibility of the owner or manager of the commercial kitchen, the design and installation are supposed to be done by professionals, right?

But, I have noticed cases where the installation and design of the extraction hoods do not comply with adequate technical criteria and therefore in the long or short term generate various problems.

I am a designer of commercial kitchens, and I have a basic knowledge of how an extraction hood should be, but in the installation part, I got the help and the opinion of some experts from several companies.

They provided me with photos, examples, and information on the reasons why an exhaust hood can cause problems, so I decided to summarize everything on this topic with photos and detailed explanations.

Here are the most common problems with commercial kitchen hoods and some tips on how to avoid or correct them.

1-Undersized exhaust hood

To begin with, this is the most basic reason why a commercial kitchen exhaust hood may malfunction.

I myself made the mistake in my early days as a designer of designing commercial kitchen hoods with inappropriate dimensions.

The thing is, I was taught early in my training as a kitchen designer that the basic size commercial kitchen exhaust hood is 42″.

This is as long as the cooking line is traditional equipment, stoves, grills, etc.

But this varies when the cooking line has equipment of greater depth and with hinged doors, such as convection ovens.

In this case, the exhaust hood should be at least 54″ deep, to be able to cover the extraction of the oven and also to be able to trap the vapors that come out when opening the oven.

This should always be taken into account in the cooking line, whenever you have equipment such as ovens, or if you plan to expand the cooking line in the future, consider the depth of the exhaust hood from the beginning.

2-Hood Filters in poor condition

Commercial kitchen hood filters are essential for proper operation, but for some reason, many establishments have these filters in very poor condition.

Filters without cleaning and also deformed filters, as if they were crushed, a filter in this condition will prevent the air that pulls the extractor to flow properly and therefore the extractor will be forced and will not work properly removing the vapors from the kitchen.

A periodic inspection of the filters and check, if they are in good condition, is essential, also check for grease accumulation.

Common errors in hood filters:

• Poorly designed
• Broken or crushed
• Not in place
• Placed inverted
• Saturated with fats
• All of the above

3-Improperly fabricated extraction duct pipe elbows

In the photo, you can see some extraction ducts with an inadequate design, at a glance you can see the error.

The angle bends in pipelines should not have orthogonal angles, this is established in regulations, the radius of the bend should be at least 2.5 times the diameter of the pipe.

If you have an exhaust pipe with this type of error, the air circulation inside the pipe will be very poor, which translates into poor air extraction in the kitchen.

This type of design error occurs when the work is contracted by people who do not have a firm theoretical approach because it is not only “knowing how to manufacture”, it is necessary to understand the dynamics of the interaction between the elements.

This same error of execution in fabrication and installation will be repeated in this topic.

4-Narrow duct sections for the volume to be handled

The size or section of the exhaust ducts is not an arbitrary or set value, it will always depend on the volume of exhaust air.

This volume of exhaust air is achieved by knowing the amount of equipment placed in the cooking line, specifically the CFM (Cubic feet per minute).

If you are interested in knowing how to calculate the CFM to know the amount of air volume in an exhaust hood, I made a complete guide on the subject that can be of help.

5-Placement of the extractor just after the elbow piping

Another very common mistake is this, to place the extractor just after the elbow pipe, ducts of equal or greater than 3 times the length of the extraction duct section should be placed, so as not to have both elements so close to each other.

In these cases, a lot of turbulence is created at that point and this increases the static pressure, decreasing the volume of air that the system can handle.

There are other common problems, related to air injection in the kitchen, which is something different from the extraction, but this deserves a separate topic.

If you know of any other errors that may be common in commercial kitchen exhaust hoods, write to me at the contact page of the website, and I will add it to the topic, I would appreciate it.