My Exhaust Fan Isn't Working Properly

A question we get on a regular basis is people telling us their exhaust fan isn't working properly. It is a simple enough question but it has a multitude of answers. While it is impossible to list every scenario, we will look at some more common issues that happen with exhaust fans no matter who the manufacturer is. Generally when an exhaust fan isn't working properly it can be classified into one of two categories – mechanical or installation.

Mechanical issues generally occur over time and are affected by a host of factors such as usage, environmental issues (living near salt water), where the unit is located and so forth. Some issues that might seem like they are mechanical could actually be installation issues and we will get into those in the next section. Generally if the fan does not operate right after installation it is most likely an installation issue rather than a mechanical one – not always but most of the time. Some of the common mechanical issues are:

The fan stops operating.

This could be the motor has worn out and has stopped running. You can expect this in older fans that have been operating for a long time. If it is a newer fan, check your warranty as many fans have at least a one-year warranty and some up to a 5 year warranty.

Fan starts making loud noises – “metal” sounds.

More than likely this is because something inside or around the fan has come loose. This could be something in the mounting system, a weld on the housing, the motor mount has come loose and so on. If it is the mounting, simply tightening the mounting screws or re-enforcing the connections to the joist or stud should solve it. If the welds on the housing have come undone this is a little harder to fix and you might be better off replacing the unit – especially if it is an older unit.

Fan starts making loud noises – “rattling” sounds.

This is typically attributed to the fan blade becoming out of balance and can sometime sound like the fan is pulsing. This happens in one of two ways. The first is the blade becomes warped. This can happen if there is excess heat or chemicals. A more common reason for this is the fan blade my be dirty and have a build-up on it causing it to be out of balance. Refer to your unit’s instructions sheets for care and maintenance. The good news is this is usually a fairly simple fix.

Doesn’t seem as if the fan is moving the same amount of air as it used to.

If the amount of air being moved decreases over time or the sound of the fan increases over time, the main culprit is usually a build up in the ducting or a blockage at either the wall or roof cap. Bird’s nests are a common issue. Check to see if there is anything blocking where the fan is exhausting.

If you determine it is not a mechanical issue, then the reason your exhaust fan isn't working could be an installation issue. In general you should notice these issues right away but there are some that will show up a little later. Some of the common installation issues are:

Fan does not turn on.

This is usually a wiring issue where they were not connected properly. Check the wiring diagram in your installation instructions. Another common issue is that sometimes people forget to restore power to the unit either at the circuit board or at the wall switch (don’t worry, it happens to the best of us).

Fan does not operated as expected.

Here is where it gets a little more difficult to pinpoint the issue and it requires a bit of investigative work. First, check to see if the size of the duct collar on the unit matches the duct size you are connecting to. If the duct you are connecting to is smaller, you will loose airflow (CFM) and increase sound (sones). Going from smaller to larger ducting is fine but reducing it can cause some issues. Second, determine how long and how many turns the ducting has before the air leaves the home. The longer the ducting and the more turns it makes, the more static pressure the air has to overcome. This will cause the fan to work harder, reduce the airflow and in many cases increase the sound. A best practice is to keep the ducting as short and straight as possible. Third is what type of ducting is being used. It is always recommended that straight, ridged ducting be used. While flexible ducting is easier to use, it can decrease the performance of the fan – especially if it has a bunch of turns and twist like was mention above. Sometimes these items can’t be avoided. If you can identify them in the planning phase however, you might be able to address them there by using a higher power and quieter fan to compensate for the performance “lose” you might experience.

Fan makes loud or rattling sounds immediately after installation.

We touched on a few of these items above, but if they are happening immediately after installation it probably has to do with how the fan was installed. With the power OFF, check to make sure the fan’s housing is securely fastened to the joist or stud. Next check to see if the fan blade is out of balance or is hitting the housing as it spins (you can spin it with your hand). Check the duct collar and connections to make sure they are all secure. Check the motor mount. Many fans have what is called a venturi or a venturi plate that holds the motor in place within the housing. If this is not installed properly or securely it might rattle or cause the fan to be out of balance.

Identifying why your exhaust fan isn't working properly can sometimes be a tricky but utilizing the suggestion we laid out in this post will hopefully help. For more information about exhaust fans, visit airkinglimited.com. If you are looking for a specific Air King model, utilize the search feature or access instruction and user manuals here.

Can I Use a Duct Reducer With My Exhaust Fan?

You decide it is finally time to replace your old exhaust fan in your bathroom. You go out and buy the new model and are excited to get it installed. One issue. When you take out the old one you notice that the duct size is different – now what? This is a common issue when replacing exhaust fans. Codes have changed over the years and where 3” duct might have been common, it is now 4” duct. Many codes and builders across the USA are even going up to 6” duct as standard. So what do you do if you have smaller size ducting in your home than the duct coming from your exhaust fan?

A common solution is to use a duct reducer. This attaches to the duct collar coming off the exhaust fan and reduces the duct size down. For instance, if your fan has a 6” duct collar but your ducting is 4”, you can use a 6” to 4” reducer. Seems simple and easy – right. Well, unfortunately it is not that simple. Many fans are not designed to be used with a duct reducer. By reducing the ducting you are creating more resistance and not allowing the air to flow as freely as it was designed to do. This will cause the amount of air you can move to be reduce and in many cases will increase the sound level of the fan. It will also make the fan work harder and possibly reduce the lifespan. This falls into the category of if it is your only option other than replacing all of the ducting and the wall or roof cap, then you might consider it.

A better option is to try and get ahead of the game so to speak. When researching a replacement for your fan, try to determine what size ducting you already have in place. There are a few ways you can do this.

1. Find the model number of the fan you are replacing and do a search online to find out the duct size. This is generally accurate but you do need to keep in mind that the person who installed it could have also used a duct reducer. 

2. When you remove the old fan you can see what size duct was used and if a reducer is in place. The issue with this is we know most people like to have the new fan on hand before taking the old one out.

3. If you have access to the fan from above (attic) you can measure the size of the existing ducting.

What about if the ducting in my home is bigger than the ducting from the exhaust fan? In almost all situations going form smaller to larger ducting will not create any issues. You will need to have an adapter installed to properly connect the smaller ducting to the larger but you shouldn’t see any increase in sound or decrease in airflow.

To learn more about exhaust fans and ventilation visit airkinglimited.com or consult a professional in your area.

Anatomy of Kitchen Range Hoods

Kitchen Range Hoods are a critical component in maintaining the indoor air quality of our homes. The kitchen is one of the leading sources of contaminates in our homes and utilizing a range hood decreases these contaminates and makes our homes healthier to live in. So how do kitchen range hoods work?

Having an understanding of how range hoods work and what they are providing is an important component to making sure they are utilized correctly. Range hoods have a two-function purpose. The first is to provide protection to the cabinets above the cooking area. Almost all cabinets are made out of wood so to protect them if there is a flare up on the cooktop is important. Over the years range hoods have greatly advanced to more than just basic protection. They have become part of an indoor air quality solution. The basic principle of kitchen range hood is to take the “bad” air being generated during the cooking process and move it (exhaust it) out or filter it.

There are two types of methods a range hood uses to better the indoor air quality. The first is to utilize an odor filter and recirculate the air back into the room. This type of range hood does not require ducting. While this will provide some improvement to the indoor air quality of the kitchen, they really are not very effective as the filters used only catch a small percentage of the contaminates you really want to remove from the living space. This type falls into the “better than nothing” category. A much better way is to have the air exhaust to the outside. These hoods still have some type of grease filter that prevents grease from building up on the hood’s motor/blower as well as in the ducting. The big benefit is all of the contaminates the hood captures will be exhausted to the outdoors and away from the living area. 

Most kitchen range hoods also have some type of lighting feature to them. These might be LED, incandescent or even halogen. When looking for a range hood, take note of the light both from an efficiency standpoint as well as the location. Generally a hood with the light at the front will provide better overall coverage of the cooking surface.

The next part of the range hoods is the duct collar for hoods that are being exhausted to the outdoors. Hoods that are recirculating the air back into the kitchen typically have an exhaust vent build into the hood itself. Hoods that are exhausting to the outdoors will have some type of duct collar either built into the hood or one that attaches to the hood. Common sizes for these collars are 3.25” x 10” or round. Round duct collars range from 5” to 10” and larger. Many of the duct collars are going to also incorporate a backdraft damper that prevents or at least lessens the amount of air coming back into the home through the ducting. A quick note – if you feel drafts coming from your range hood, you might want to upgrade your backdraft damper. Air travels through the ducting from the range hood to either a wall cap or a roof cap. While these components are not necessarily part of the fan, they are integral components that are required. Wall and roof caps vary in function, features and costs. Two common features are bird screens that prevent birds from building nests in the ducting (yes, it does happen and it is more common than you think) and backdraft dampers. Backdraft dampers on the wall or roof cap provide an extra layer in addition to the one on the range hood to prevent backdrafts.

These are the main components of kitchen range hoods. In addition some fans will have extra features like continuous operation, thermostats that turn the unit on or off and more. For more information of the range hoods available through Air King visit airkinglimited.com

Anatomy of Exhaust Fans

Exhaust fans play a pivotal roll in maintaining the indoor air quality of our homes. Utilizing them decreases contaminates, reduces moisture and makes our homes healthier to live in. So how do exhaust fans work?

Having an understanding of how exhaust fans or as they are sometimes called – bath fans work is an important component to making sure they are utilized correctly. The basic principle of an exhaust fan is to take the “bad” air inside your living space and move it (exhaust it) out. That air is then replaced with fresh air. It is a fairly simple concept.

The exhaust fan’s main component is a blower of some type. Lower end units will utilize a fan blade that looks similar to a typical portable fan. Higher end units will utilize a blower wheel or as some people refer to it, a squirrel cage. Blower wheels generally are able to produce more ventilation at a quieter sound level. In either case the wheel or blades turn and generate airflow that is directed through the fan’s duct collar.

The next part of the exhaust fan is the duct collar. Exhaust fans must be ducted to the outdoors and run through ducting in the home to either a wall cap or a roof cap. While these components are not necessarily part of the fan, they are integral components that are required. The duct collar of the fan is connected to the ducting from the home. Ducting can range from 3 inches to 6 inches in typical residential homes. More and more new construction is moving to 6 inch ducting as it provides better airflow with less resistance. It is important to match the ducting size to the size of the exhaust fan. For instance if you have 4 inch ducting but have a 6 inch ducted exhaust fan you will need to reduce the ducting down to fit. This will make the fan work harder, reduce the airflow and increase the sound level.

A second part of the duct collar is the backdraft damper. This is a flap that closes to prevent drafts from coming back into the home. Backdraft dampers are usually either gravity closing or spring loaded. The way they work is when the fan is operating and blowing air out of the collar the force of the air opens the damper. Once the unit is shut off the damper will either “fall” down on gravity type dampers or close with spring-loaded dampers, sealing off the ducting.

The next component of an exhaust fan is the housing. The housing holds everything together and is what is installed into the ceiling. Housings come in many different sizes and are installed in different ways. Common installations include hanger bars that slide into a channel on the housing and then extend out to connect to the ceiling joists. A second mounting type is mounting tabs. These are tabs on the housing that install directly to the ceiling joist. Other mounting types are ones such as with the Air King BFQ series that have a snap-in bracket.

So far all the components we discussed are ones you won’t see once the fan is installed. The one that you will see is the grill. Like housings, grills come in all different sizes and shapes. The grill has a few functions. First is to cover up and protect all the inter workings of the fan. Second is to be aesthetically pleasing - no one wants an ugly hole in their ceiling. Lastly the grill provides a balance of décor and function as it needs to be able to allow enough air to come into the fan without restricting that air.

These are the main components of an exhaust fan. In addition some fans will have extra features like a light, heater function, humidity sensor, motion sensor and more. For more information about the exhaust fans available through Air King visit airkinglimited.com.