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.

How Does ENERGY STAR® Certified Ventilation Help?

For the most part almost everyone in the United States has at least seen the ENERGY STAR® logo and many understand what it signifies. Many people however only think that certification is for things like TVs, computers and appliances. While they are some of the more “big ticket” items, there are many categories of products that can earn certification including ENERGY STAR® certified ventilation.

So what sets certified ventilation apart from typical products? Here are a few of the main items. ENERGY STAR® certified ventilation must perform at a higher efficiency than standard ventilation solutions. Efficiency is measured by taking the amount of air the unit moves (measured in CFM – cubic feet per minute) and dividing that by the amount of energy (Watts) needed to operate the unit. To put this in perspective a standard low end or entry-level exhaust fan operates at about 1 watt per CFM or worse. In contrast a certified unit has to operate at a minimum of 2.8 CFM per watt with some units exceeding that and operating as high as 19 CFM per watt.

A second way ENERGY STAR® certified ventilation products stand out is they are required to offer a longer warranty. While this might not sound like a big deal, it actually is. With a longer warranty, there is more peace of mind that that product is going to last a lot longer and is constructed of high quality parts. In the case of ventilation products that typically means a better motor.

For units that have a light feature, which include some exhaust fans as well as most range hoods, the light bulb must be included or integrated with the unit and it must be a certified LED bulb. The lighting in these units can sometimes be the biggest energy draw of the unit. For instance changing from a 60-watt incandescent light bulb to an equivalent 8 watt LED is saving approximately 52 watts.

Lastly, and this one might seem a little out of the ordinary is that there are sound restrictions on the units. For most units, they must operate at or below 2 sones. Sones are the unit of measurement for sound in ventilation products. We have explained sones in some of our previous posts but basically 1 sone is the sound your refrigerator makes and 4 sones is about the sound of a typical conversation.

When you put all this together, it is hopefully clear that ENERGY STAR® certified ventilation is going to be a much better product than a standard one. For more information regarding ENERGY STAR® certified ventilation solutions from Air King including exhaust fans, range hoods and fresh air intake, please visit airkinglimited.com. For more information about ENERGY STAR®, please visit energystar.gov.

Is the Code Enough? Part 1

There is a commonly used four-letter word in the building industry that typically elicits a range of emotions – code. Building codes are good things. They ensure our homes are built to a standard that will keep us safe and provide a good living environment. For the most part, just using common sense and proper building techniques will meet a lot of the building codes. But, are the codes good enough? Over the course of the next few blogs we are going to take a look at a few specific areas of the home and some of the general ventilation building codes that apply to them.

At the time of this blog, there is a large company using the slogan “just okay is not okay”. We can have this same approach when it comes to code compliance. In general building codes are a minimum standard but sometime we should be looking closer at what that minimum means for our standard of living. Let's take a look at typical exhaust fans. There are a lot of codes across the country in regards to bathroom ventilation. Some codes just say you need a window in the bathroom and you are good. If this is the code in your area, we would highly recommend exceeding the code. In earlier blogs we have gone into detail as to why you need an exhaust fan in your bathroom so we are not going to say much in this blog. Most of the codes will call for an exhaust fan to be installed in the bathroom. This is a good thing, sort of. Something is better than nothing, but it is conceivable that you can meet code but not be effectively ventilating your bathroom.

Here is the scenario. You have a 10ft. x 10ft. bathroom. That is a total of 100 square feet. The minimum sized exhaust fan you will need is 100 CFM (cubic feet per minute). That should meet your building codes, but will it be effective? If you live alone in a mild climate and take short showers, it probably will be very effective. If there are 4 people sharing the same bathroom, who all take hot showers, 100 CFM might not get the job done. Going up an extra 10-50 CFM could be the difference between effectively removing the moisture from the bathroom or not.

Most people do not spend time thinking about their exhaust fan (it’s okay, we don’t take it personally). The fact of the matter is that your exhaust fan is something that is or should be used on a daily basis so it stands to reason it should be effective. Before we go any further we will come right out and say it – yes, generally exceeding the minimum requirements will mean a more expensive exhaust fan. Let's put that into context however. Let's say you need to spend an extra $50 to upgrade your exhaust fan if you are building a new home. The average cost of a new home in 2019 was around $300,000 (varies depending on what source you use). When you add $50 or even $100 to a $300,000 home, it seems like a fairly easy choice.

Okay, what do you get for that extra $50 to $100? We already talked about more effective ventilation depending on your living style but there is also a comfort level to it. Upgrading your ventilation usually includes lowering the sound level and even the power consumption. Meeting the minimum code might include a fan that you will definitely hear running. Exceeding the code opens up options for fans that you can barely hear running.

Building codes are in place to ensure safety and health and we are very thankful that we have men and women working very hard to keep up with them and pushing the industry forward. The next time you hear the phrase “meets code” just stop and think  - is meeting the code all I really want to do? For more information about Air King exhaust fans visit www.airkinglimited.com.

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

Time it right – using timer switches with your exhaust fan or heater

Have you ever had a conversation with your children or spouse about leaving lights on in the house? Okay maybe “conversation” isn’t the correct word but I think we have all been there and probably on both sides of it.

While we might not be able to help in all rooms, the bathroom is definitely one that has an easy solution – timer switches. A timer switch is an excellent and usually very easy upgrade to a bathroom that allows you to control as little or as much as you want.

Because bathrooms are used for a limited amount of time, timer switches make a lot of sense. Switches come in all forms and functions, from the traditional dials to programmable electronic ones. When choosing a timer switch, you want to consider a few things. 

1. Can the switch handle the power requirements needed. If you are using a timer switch to control a heater function (and we highly, highly recommend you do) you want to make sure the switch is rated for it. Switches will have a rating on them with the maximum amount of watts or amps it can handle. Simply match that to what you are controlling with the switch. For instance if you have a heater that uses 1350 watts - makes sure the switch is rated for at least that amount. 
2. What type of features do you want on the switch. When using with a combination fan and light, a useful function is a timer switch that turns the light off but allows the fan to run for an additional amount of time. This allows the fan to complete the ventilation process without having to have the light on during the entire time.
3. Make sure the switch can accommodate the amount of time you typically spend in the bathroom. If it takes you 40 minutes, a 15-minute timer is probably going to be more of a hassle for you than help.

To learn more about timer solutions, visit www.airkinglimited.com

The exhaust fan choice dilemma

So you need an exhaust fan. How hard can it be to choose an exhaust fan? You go online and type in “exhaust fan”. 14 million results come back. You click on one random site and there are 300 results with all of them looking almost the same. Maybe this isn’t going to be as easy as you originally thought? Hopefully we can help navigate the confusing world of choosing a bathroom exhaust fan.

There are two basic functions to start with: air movement measured in Cubic Feet per Minute (CFM) and sound measured in Sones. There are many considerations for CFM, but we are going to stay with the basics for a typical homeowner. The general rule is 1 CFM per square foot of space with standard 8 foot ceilings. So if you have an 8 foot x 10 foot bathroom you would need at least an 80 CFM fan. This would be the minimum ventilation. Depending on your usage, you might consider a slightly larger fan to make sure you have enough power to clear the room.

The second consideration is sound – sones. A rating at or below 1 sone will be very quiet. 1 to 2 sones will still be quiet but anything over 4 sones starts to get loud. The sound rating of a fan will typically influence the cost with quieter fans costing more.

The next consideration is if you have an existing fan or this is a brand new installation. Items such as what type of ducting could play into your decision. Many older fans used 3” ducting. Newer fans are typically going to have either 4” or 6” ducting. This is important to know because if your fan is set up for 4” ductwork and you try and use the existing 3” duct work, the sound level will increase and the performance level will decrease.

After those considerations it comes down to style and functions. Do you want a light? Do you want a fan that automatically turns on when you enter the room or when the humidity level rises in the room? There are units with a decorative grill. These are all personal choices to fit your lifestyle and décor. Air King has a large selection of energy efficient, quiet exhaust fans to meet the needs of almost any home. To learn more about Air King’s bathroom exhaust fans, visit www.airkinglimited.com.

Location, Location, Location – where is the best place to install an exhaust fan?

Seems like a fairly easy question that the exhaust fan should go in the bathroom – right? The simple answer is yes, but we want to look into it a little deeper than that.

When using an exhaust fan inside a bathroom, the exact location can have a large impact on the effectiveness of the fan. For instance, in a typical bathroom, the shower is going to produce the most amount of moisture that needs to be exhausted out of the home. By placing the fan within the shower stall, you are increasing the effectiveness of the fan as the moisture can come straight up into the fan and out of the home. Conversely, if the fan is on the other side of the room, the moisture from the shower has to travel across the room and out.

CAUTION: In order for a fan to be used in the shower stall it needs to be tested and approved for this use. It needs to say something to the effect of “Approved for tub/shower use on a GFCI circuit”. The GFCI (Ground Fault Circuit Interrupter) is a safety feature that will shut the power off if moisture causes a hazard. Fans that include a heater function should never be used inside a shower stall.

If your fan can’t be used inside the stall, it is suggested that it be installed right outside of the stall – minimizing the distance the moisture has to travel. In larger bathrooms, two fans might be necessary. One installed in the shower stall and the other installed above the toilet. Once again, the goal is to locate the fans so they are as close to the source of contamination (moisture or odor) as possible.

Exhaust fans are no longer just for the bathroom. In future post we will look at whole house ventilation as well as ventilating areas such as garages, laundry and utility rooms.

To learn more about Air King’s exhaust fans, visit www.airkinglimited.com