Duct it right – how to properly duct your exhaust fans

You did your homework, picked the perfect exhaust fan for your room and are now ready to install it. You have now entered a make or break crossroads in the installation process - how are you going to connect the ducting to the fan.

Okay maybe that is a bit dramatic, but the ducting is a key element to the installation process. There are basically two scenarios you will be faced with, existing ducting and new ducting. If you are replacing an old fan, there is probably ducting already in place. It is very important that the ducting be the same size as the new fan’s duct collar. Many older homes utilized 3” or 4” round ducting. Many newer fans are utilizing 6” ducting. Duct reducers are available to make the transition to smaller ducting, but this will increase the sound level of the fan and decrease the performance level – so that perfect fan you just bought, might not be so perfect after all. The best thing to do is to replace the ducting to match the size the fan requires.

With a new installation, you will need to run ducting anyway, so make sure it is the size required by the fan. It doesn’t end there. You also want to use the shortest and straightest ducting possible. This allows the fan to perform at an optimal level. The longer the ducting and the more twists and turns, the less effective the fan will be. While rigid ducting is the best, if you need to use flexible ducting, make sure it is cut to length and as straight as possible. If the ductwork looks like some mythical sea creature, it is probably not an optimal installation. Each twist and turn builds up Static Pressure (SP), which causes the fan to work harder to push the air through. Think of blowing air through a large straw. If it is straight, it’s not all that difficult, but if you bend it a few times, it is a lot harder to blow air through it. Insulating your ducting will also help with any condensation issues. In colder climates, as the warm air passes though the cold ducting, condensation builds up and can actually cause water to come back through the ducting and into the room.

To finish the ducting installation, you want to make sure the air is making it outside of the home. The worst thing you can do is have air blowing directly into your attic or wall cavity. Air coming from a bathroom will most likely be hot humid air, over time that will build up in the form of mold and mildew. Making sure all seams are sealed is also critical. If air is leaking out of the ducting as it comes through, it is not making it to where it needs to go. Using a properly sized roof, wall or gable mounted cap will ensure that the air is going where it needs to go.

To learn more about exhaust fans and ventilation visit www.airkinglimited.com.

Take it outside – Exhausting your fans outside of the home.

You’ve read all the articles about proper ventilation and improving indoor air quality. You went out and purchased the perfect exhaust fans for your home and are now ready to install them. Good for you, great job. As you start the installation you realize that you will need to run ducting for these fans and there isn’t any existing ducting. No problem, you’ll just run it into the attic, away from the living area. HOLD IT RIGHT THERE! We are going to need to stop you.

Making sure you exhaust the air outside of the home is one of the most important steps when it comes to ventilation. Even if you have existing ducting that you are connecting to, you want to confirm that it is running outside the home. If you are like most people, the first question is why, what’s the big deal.

The most commonly mistaken place people run their exhaust fan into is the attic. Now stop and think about your attic. It is not the most pleasant place to begin with. In the summer it is probably very hot, even if it is properly insulated. Now take that hot area and add almost 100% humidity to it as the moist air from your shower is pumped into the space. Before long you will have what feels like a rain forest in your attic. This will quickly turn to mildew and then mold. Because it is an attic and not a common living space, it might be years before you detect that mold is growing (think of those renovation shows on TV where the host finds mold that has been growing for years – not a pleasant sight). Anytime you find mold growing in your home, it is not a good thing. All that can be easily prevented by just exhausting the fan outside the home through a wall, roof or gable mounted cap.

To learn more about ventilation visit www.airkinglimited.com.