Is a Dirty Exhaust Fan a Good Thing?

It might seem like an odd question, but is a dirty exhaust fan actually a good thing? The simple answer is no, but to answer the question fully, we need to look at it a little differently.

What is the Purpose of an Exhaust Fan?

The main purpose of an exhaust fan is to improve the indoor air quality of the room by removing moisture, odors and contaminates from the living space. This means that particles are going to be traveling through the exhaust fan and ducting.

How is a Dirty Exhaust Fan a Good Thing?

A dirty exhaust fan, or one that has a build-up of dirt on it is a good thing in the sense the fan is operating correctly and effectively. As contaminates travel through the fan, they are inevitably going to build up on the inner workings on the fan. Most commonly on the fan blade and the fan grill. In its simplest form, this means the exhaust fan is doing its job and removing the unwanted contaminates from the living space. If you exhaust fan runs for any length of time (months/years) and you never need to clean it, it means one of two things. One, you live in a home that has no dust, no contaminates, no pets, and probably no people. Second, the fan is not being used as much as you think it is or should be.

How is a Dirty Exhaust Fan a Bad Thing?

Before the screaming, yelling and rebuttals start pouring in – yes, we agree that a dirty exhaust fan is not a good thing for the overall function of the fan. As dirt and debris builds up in and on the exhaust fan as well as the ducting, the performance of the fan is going to reduce. You will typically see a decrease in the amount of airflow the fan is able to produce and an increase in the sound level. As we mentioned before, the most common place for dirt build-up is on the fan blade in the form of what is going to look like lint. This build-up on the fan blade adds weight and causes the motor to have to work harder. This not only can reduce the effectiveness of the exhaust fan; it can also shorten the motor life. The same holds true with build-up in the other areas such as the grill and especially the ducting. The narrower the openings become, the less effective the exhaust fan will be.

What Should I Do?

The best way to combat a dirty exhaust fan is to have a regular cleaning schedule. Most maintenance can be done by the average homeowner. There are however a few steps to take to reduce the chance of injury or damaging your fan.

First and foremost, consult the cleaning instructions for your particular model. While most cleaning instructions for exhaust fans are similar, there are differences. Fans with a light will have slightly different instructions than one without. In general, never use water or liquid cleaning products directly on the fan motor. For parts you can use a liquid cleaner or soap/water to clean, always makes sure they are completely dry before reinstalling and restoring power.

Second, always make sure to turn the power off to your exhaust fan before starting any cleaning or maintenance.

Third, if you are unsure of how to clean your exhaust fan, consult a HVAC or Electrical professional. Duct cleaning service can also be another resource to consult.

While we will admit, asking the question – Is a Dirty Exhaust Fan a Good Thing, is a bit of a leading or trick question, it does prove that it is doing what it is supposed to be doing. As we outlined, taking a few steps to ensure your fan is clean and properly maintained will benefit your home’s indoor air quality as well as the life of your fan.

Learn More

To access Air King user manuals, including maintenance instructions, visit the User Manuals section of the Air King website. To learn more about Air King exhaust fans, visit the exhaust fan section of the Air King website.

Ventilation Diagnostic – 5 Ways to Check Your Bathroom Exhaust Fan

The ventilation of your home is a very important component of proper Indoor Air Quality (IAQ). If it is not working properly or is ineffective, it can lead to larger issues. Here are 5 ways you can insure your exhaust fans are operating properly:

1.    Sizing – A common error made when choosing an exhaust fan is the size or how much air does it move. This is measured in Cubic Feet per Minute (CFM). A quick way to see if you have the right amount is to measure the length and width of your bathroom and times those numbers together. For instance a 10 foot by 10 foot bathroom is 100 square feet. The general rule is a minimum of 1 CFM per square foot. In our example you will need at least a 100 CFM exhaust fan. Typically there is a sticker inside your fan that lists the CFM. If not and you can locate the model number of the fan, you can use a directory such as HVI (hvi.org) to look-up the airflow. If the airflow of the fan is less than what is needed, you might want to consider replacing the unit. Note: there are other factors such as duct length, height of ceilings and more that can contribute to the airflow of the unit. For our purposes we are just concentrating on some simple ways to check.

2.    Obstructions – Once you have determined that the airflow of you fan is what it should be the next item to look at is obstructions. Depending on where your fan is exhausting to will determine how easy this is to do. First do a visual test. Do you see any debris in or around the wall or roof vent? Common obstructions are items like birds nests. If your vent has louvers, make sure they are working and are not frozen shut. CAUTION: if you need to use a ladder or climb on your roof, make sure to adhere to all safety measures to avoid injury.

3.    Cleaning – After checking for obstructions outside, it is now time to check inside in the form of dirt and debris build-up in the fan. The performance of your fan can be reduced if it is not properly maintained. If there is a build up of dirt or debris on the fan blades/blower you are probably not getting the full airflow. The good news is this is an easy fix. Follow the cleaning instructions in the user manual that came with your fan (or access them through the manufacturers website). Make sure to follow all safety precautions including turning off the power supply to the fan before starting.

4.    Living Test – We sometimes think we have to have some expensive piece of equipment or call an expert in to diagnose things. That is not the case with bathroom exhaust fans. There is a very simple test we will call the living test. Is your bathroom fan working the way you want it to? After you get out of the shower is the room full of steam for what seems an eternity? Does mold and mildew grow faster than you can clean it? These are some common signs that your fan might not have enough airflow to do the job. As listed above, you can try and see if it is an obstruction or it needs cleaning but you might want to consider increasing the airflow by replacing the unit. Even if you determine that the airflow of the fan matches the size of the room, different factors can be at play that might require a larger CFM fan.

5.    Function – When we talk about function, we are talking about two factors – mechanical and user. For mechanical, is the fan physically working? When you turn the fan on, does it operate? I think it goes without saying that if the fan is not operating, it either needs to be repaired or replaced. This might sound like a duh moment but we are always amazed how many times replacing an exhaust fan seems to be a secondary project. The second factor is the user. How many times have you used a bathroom without turning the fan on? We are not judging and forgiveness is available. The main reason people give for not using a bathroom exhaust fan is the sound. Even if the right sized exhaust fan is installed, if it isn’t turned on because of the sound level, then it is as if there is no exhaust fan there at all. There are two ways to solve for that issue. One would be to replace it with a quieter model. Exhaust fans have come a long way and now, there are many models that operate at an almost silent level. A second way is to install either a humidity or occupancy sensor that will automatically turn the fan on and off taking control out of the hands of the occupants. That won’t solve the sound issue, but it will ensure the fan is operating.

To learn more about ventilation, available exhaust fans and Indoor Air Quality, visit the Air King site at www.airkinglimited.com