Range Hood Purpose and Safety

Range hood Solid state home inspections

Kitchens are one of the most dangerous places in our homes and this is for very good reason. We use large amounts of heat, electricity, natural gas, sharp knives, and can slip on spills of oils and water. For home inspectors, the kitchen presents many areas for inspection but the range hood often presents a life safety danger.


Why Do We Have a Range Hood?

Range hoods are part of our climate control system inside our homes and kitchens. They can improve our inside air and climate in our homes by:

  • Removing Humidity - Nearly all cooking methods vaporize a certain amount of moisture in the form of steam. Surface moisture is easier to manage but if too much moisture is allowed to stay in the home, it can condensate in wall cavities and attics allowing rot to grow. Mildew and mold growth in attics of homes that cook with a lot of humidity are common to find in home inspections.
  • Removing Smells - Smells can be a nuisance for home occupants. A range hood fan can create negative air pressure in the cooking area preventing fumes from spreading to the rest of the home.
  • Removing Oils - As vapour rises in cooking, some of these vapours contain oils from cooking. The range hood can filter much of this oil before it has a chance to stick to other surfaces in the kitchen. If kitchen surfaces have a thin layer of grease, it is often from an under-used or malfunctioning range hood.
  • Exhausting Gases - Gas ovens and cooktops generate exhaust gasses like carbon monoxide as the natural gas burns. A range hood will help exhaust these gasses from the home keeping the air safe for occupants.
  • Controlling Heat - The working space around the stove can become quite hot when cooking with many cooktop elements and/or oven use. A hood fan help draw cooler air into the work space making it more comfortable for the cook.


Recirculating Air versus Exterior Exhaust Air

Most range hoods can operate in either a 'recirculating' air mode or an external exhaust mode. As a recirculating range hood, air does not get exhausted outside meaning humidity, smells, and exhaust gasses do not leave the home. Recirculating fans are still good for removing some cooking oils and controlling the working area temperature for the cook.


To be most effective and to increase home occupant comfort, a range hood should be connected to an external exhaust. The external exhaust means the humidity, smells and exhaust fumes are also controlled in addition to heat and oils.


Life Safety Concern - When a gas range is used, the exhaust fan MUST exhaust outside the home to remove the toxic combustion gasses. Gasses like carbon monoxide can build up in the blood stream causing headaches, dizziness, and ultimately death.


Safe Cooking Clearances

The cooking surface can be a busy place for cooks. Hot waters, oils, and surfaces are present. There is also often a lot of lifting and moving of pots and pans and adding ingredients. For this reason, there needs to be a safe working height between the range hood and the cook top.


Minimum clearances for safe working space are commonly recognized to be 18" however even higher clearances are better. In commercial kitchens, the exhaust fans are often above the heads of the cooks. Range hood manufacturers do specify the maximum height above the cook surface based on the amount of air flow the range hood generates. If a range hood is too high, it won't exhaust all the fumes and vapours, too low and it is unsafe to work under. Always consult the manual or manufacturer to learn the proper clearances if you are changing a range hood configuration.


Built-In Microwaves with Range Hoods

Many built-in microwaves are designed with exhaust fans and lights to be mounted over the stove. This configuration is excellent for saving space and providing the fan is correctly exhausted to the outside and provides adequate air flow for this cooking area, this is a great configuration for home owners.


What do Home Inspectors Look at With Range Hoods?

Many home inspectors do not look at the appliances in the home (Solid State Inspections does) but all home inspectors should review the range hood for correct installation and safety.


Common Deficiencies with range hoods found in home inspections are:

  • Externally Connected but set as Recirculating - Most common range hoods can operate as either recirculating or as externally exhausting. Unfortunately, installers commonly connect all the exhaust components but then configure the range hood to recirculate air only. This can be corrected by a handy person to correctly exhaust outside with some minor repairs.
  • Leaking Exhaust - Connections of exhaust fans to the vent systems and sometimes the vent lines themselves are often very poor or have become poor as connections move over time. It is common to feel air drafts in the cabinet above the range hood which indicate spilling air. Repairs can usually be done easily by a handy person.
  • Natural Gas Appliance with Recirculating Air - When either of the two situations above happen and there is a gas appliance, potentially life threatening gases can endanger the home occupant. This is a major life safety concern for home inspectors to find and the home inspector should alert even the current occupants that they have a health risk in the home.
  • Not Operating or Poor Operation - Weak or inoperative fans or even very clogged filters can prevent correct operation of the range hood. Repairs may require replacement or simple cleaning. If this involves a gas appliance, this is a major safety concern for the home occupants.
  • Light Bulb not Operating - In most cases, this is just a burned out light bulb however home inspectors need to report it could also be a defective range hood.
  • Poorly Mounted - Some range hoods are either installed poorly to begin with or in time vibrations and mechanical damage has caused the range hood to be less secure. This can allow air flow to escape or the range hood to fall, both of which can be safety hazards for occupants if not repaired.
  • Inadequate Clearances - Inadequate clearances happen most commonly when home owners replace the original range hood with a built-in microwave. Built-in microwaves are often taller than normal range hoods and should be attached to a shorter cabinet above to compensate. Often when this is done, the cooking clearance becomes about 16" which is unsafe and needs to be reported by the home inspector as a potential safety hazard.


Final Thoughts

When range hoods are correctly operating in a home, occupants often give little thought to them but correctly used and maintained, they can protect the home from hidden damage and improve the quality of the air and climate in the home. If you have any concerns about the safety of your range hood, particularly if you have a gas appliance, call your local home inspector for a consultation so you know your home is safe and solid.


By James Bell - Owner/Operator of Solid State Inspections Inc.