So you want to open a restaurant, only to find there’s no way to exhaust your kitchen hood to the outside like a class 1 cooking restaurant. Maybe you’re a sushi restaurant that doesn’t have a hood and is considered class 5 cooking, but now you’d like to add some tempura to your menu.

It’s important to know the pros and cons to help you make your decision on whether to use a ventless hood that’s class 4 cooking, or a standard kitchen exhaust system that’s class 1 cooking.

What is standard kitchen exhaust?

A typical restaurant kitchen exhaust is comprised of four major components:

  1. Kitchen exhaust fan 
  2. Hood
  3. Make-Up Air Unit
  4. Hood fire suppression 

As you cook, the products of combustion rise up and become trapped within the hood; known as capture and containment. It is then pulled through the grease filters, which remove most of the grease.  Next, the exhaust enters the grease duct, travels up to the kitchen exhaust fan, and is expelled into the atmosphere. Simultaneously, a make-up air unit supplies the restaurant with fresh air to prevent negative pressure in the restaurant. You can read up on the importance of make-up air in another article on restaurant odours.  

How ventless hoods work

Ventless hoods are typically comprised of a grease filter, pre-filter, high-efficiency filter, carbon-filter, integral hood fire suppression, and a fan.  The operation of how a ventless hood works is by first extracting the larger grease particles via the grease filter.  The grease filter is much like what you see on a typical class 1 hood, it uses centrifugal acceleration to remove the heavier grease particles.  This grease then drains into a cup which is manually drained by the restaurant operator.  The pre filter and high efficiency filter remove the remainder of the grease particles by physically trapping them in their media. The carbon filter helps remove some of the odours.  

Below is a diagram (care of Wells) of a typical ventless hood and how it operates:

4 Stage Filtration

Stage 1: Stainless steel baffle filter

Stage 2: Fire rated pre-filter

Stage 3: High-efficiency air filter

Stage 4: Carbon/charcoal filter

4 Stage Filtration of a ventless hood

ventless hood filtration system


The Pros and Cons of installing a Class 4 Ventless Hood


  1. Ease of installation as less construction is required when compared to class 1 cooking
  2. Cost savings due to no grease duct and external kitchen exhaust fan required 
  3. Minimal construction time which allows you to open your doors sooner


  1. Only electric cooking appliances allowed, NO GAS. Typically, you need a minimum of 400amps on your electrical panel.
  2. There are strict parameters set out by the manufacturer that limit the kilowatt, temperature and dimensions of the cooking appliances. Thus not any cooking appliance may be used 
  3. May be noisier than a standard kitchen exhaust system
  4. Odours and heat will remain contained in the restaurant
  5. Still requires general exhaust and make-up air unit

In some cases, it is simply not practical or even possible to install a standard kitchen exhaust system. For example, if your restaurant is on the ground floor of a multiple story building, and you can not exhaust out the front, back or up to the roof. In this case, it may be a good option to go ventless. However, you also need to consider if you have enough amps, are you okay with trapped odours and noise, and elevated heat temperatures in the restaurant?

In our experience, ventless hoods are a good option for a sushi restaurant that wants to add a 14″ fryer for tempura, or a restaurant that is mostly take-out so you don’t have a lot of customers to complain about the odours.

If you have any questions, please don’t hesitate to reach out to us and we will assist in making a proper design solution for your space!