Can I Use Flex Duct For Bathroom Fan?
The first thing you need to decide is if you are going to install a bathroom fan or not. If you have decided to install a bathroom fan then it is time to choose the right type of duct. You will want to make sure that your new duct meets all codes and regulations. This is necessary if you want to ensure the safety of your bathroom and the people inside of it.
If you decide that you do not want a bathroom fan then you should still duct the bathroom. There are many reasons for this. The most important being safety.
If you do not vent the bathroom properly then you are looking at a house that could potentially lose its entire HVAC system. If you are like me then you probably do not want to be standing in a room of human gas.
I also like the way that a vented bathroom looks. There is something about seeing a vent on top of the roof and having it spit out clean air that makes a bathroom look so inviting. Now, it is time to pick the right kind of ductwork for your bathroom.
When it comes to metal ductwork, galvanized is the way to go. It is incredibly durable and can handle the load of a bathroom exhaust fan without any issues. It is also not going to rust. If you have a galvanized duct then you will never have to worry about the duct rusting through and causing a back draft.
Galvanized duct is also not going to deteriorate over time. This means that you can rest easy knowing that your ductwork is not going to fall onto your head while you are in the shower.
Aluminum is a very soft metal. It is very malleable and can be easily cut. If you have aluminum ductwork then it is possible for some idiot to actually saw through it. If the sawing was done properly then you are fine.
If not then you could have a major problem on your hands. The problem is that aluminum expands and contracts at a much faster rate than galvanized duct. If you have a bad seal then you will definitely experience back drafting. This can be extremely dangerous.
PVC duct is the worst kind of duct that you can possibly use for your bathroom fan. It is very brittle and breaks very easily. This means that you could potentially be breathing in little pieces of plastic. Over time, this will cause issues with the respiratory system.
It is also very easy to hack saw through it. If the person hacking sawing through it does not know what they are doing then they could puncture through the duct and cause a back draft.
Nowadays they make vinyl duct that is stronger and more durable than ever. This type of duct is very flexible and can easily be bent into any form or shape. It is also easy to cut and glue. This is the duct that most people use for a bathroom fan because of how cheap it is to buy.
There are many problems with using vinyl ductwork for an exhaust fan.
The first and biggest issue is that it is not very durable. The vinyl is very thin and can easily rip or tear. It is also very flimsy and will collapse in on itself when bent around a corner. If the vinyl duct is not anchored down properly then it could potentially fall down the hole that it was installed in.
Another issue with using vinyl ductwork for the bathroom fan is moisture. It is very easy for moisture to build up inside of the ductwork. This can cause all sorts of issues with mold and mildew. Moisture can also cause the vinyl to rip or tear.
So in conclusion, galvanized metal duct is the best choice for any bathroom exhaust fan. It is durable, flexible, and can stand up to moisture without sustaining any damage. The only problem with galvanized ductwork is the amount of money that you have to spend on the metal. It costs a lot of money to have it shipped to your house.
On top of that, you have to get someone with a welding machine to come out and weld the pieces together. It is a lot of work and a lot of hassle. Most people don’t have the time or money to do that type of thing.
Galvanized ductwork is a great way to go if you have the resources and time to install it. If you do not then vinyl or aluminum ductwork will have to do. Just make sure that you are careful where you install the exhaust fan and how you install the ductwork. You want to avoid having any back drafting happening.
If there is too much back drafting then your fan isn’t going to be very effective.
If you are wondering how to seal the ductwork, then you can use mastic, foil tape, or metal tape. For the best results you should have a professional install your exhaust fan and ductwork. If you absolutely cannot afford to have a professional do it then you need to at least buy the materials needed and try your best.
If you try to cut corners and end up messing up, you could seriously hurt yourself or even die from asphyxiation.
A good way to check if your fan is working properly is to turn it on and put your hand near the exhaust vent. If you are feeling any suction then you will know that your fan is bad.
If that is the case then you need to get your duct sealed better or have a new exhaust fan installed.
When it comes to exhaust fans, bigger is not always better. In fact, if you have a larger fan that is pulling in a large amount of air then it is going to take longer for all of that air to get replaced with fresh air. A smaller fan will be able to exhaust the air out of the room faster since it is taking in less air. This will help maintain a constant flow of fresh air in the room, which is what you want to happen.
Installing an exhaust fan is a very simple process. All you have to do is cut a hole in the wall that opens up to the outside. You then mount the exhaust fan through the wall. The fan is then wired up and it is ready to go.
You want to make sure that the fan is large enough to move all of the air in the room. The bigger the fan, the more air it is going to move. You don’t want a tiny little fan that is only going to exhaust the air out of the room at a snails pace.
Most fans have a little guide book that tells you how much air they move for each fan size. The most common sizes are 80, 100, and 120. The 120 is the largest fan that you can get. Don’t go overboard and get a 200 or larger fan.
That would be overkill and you would be paying a lot of money for something that you don’t need.
The standard size for a fan that will adequately exhaust the air in a room of normal size is an 80 cm fan. If the room is larger than average then you will need to go up to a 100 cm fan. A normal sized bedroom would be adequately moved with an 80 cm fan.
Always keep your pets in mind when installing your fan. You don’t want the fan to blow directly on them or else they could end up with hair all over them and a wild mess on their fur. You also don’t want them to be in the path of the exhaust at all either.
Let’s say you have a living room that is 10 feet by 20 feet in size. This means that you are going to need at least a 100 cm fan in order to exhaust all of the air out of the room within a reasonable amount of time. Anything smaller and the room is going to retain a lot of heat which leads me to the next section.
Before you buy your exhaust fan you need to know how much insulation you have in your walls. The thicker the walls, the more air is going to be retained. This can drastically cut down on how well your exhaust fan works and that defeats the purpose of installing it in the first place.
Make sure you buy your exhaust fan before you insulate your walls.
If you have to insulate your walls, make sure you only use the thinnest insulation that is required. Use as much open space as possible.
You want to have as much free space inside the wall as possible so that you will get the maximum amount of air flow.
You can put a little more thought into insulation of the ceiling too. You don’t have to leave it all open, but you can create little “chimneys” that allow the air to flow in one direction. This creates a nice breeze in the room.
If you are going to create these little chimneys, divide your ceiling into small squares using chalk or stain. Make the squares large enough that you could fit your arm through if you wanted to.
From here, you are going to staple thin strips of wood over the wall in a specific pattern. The strips of wood will direct the air from the fan in a specific direction so that a breeze is created in the room.
Start with one of the walls. On the side where you have your fan, staple the first strip of wood about 2 feet from the floor and about a foot in from the wall.
Staple a strip about every 2 feet up the wall and 1 foot in from the wall. Don’t go any higher than 8 feet or you could have a problem with your fan.
When you get to the ceiling, take it down 1 foot and start again. Do this about every 2 feet until you reach the other wall.
You should now have a nice little “chimney” where cool air can come in through the bottom and be blown out of the top.
Now do the same on the other wall.
If you have done this right, then you will get a gentle breeze throughout the room when your exhaust fan is on.
This is a very simple and cost effective way to get your room extremely cool for very little money. I have seen this method used in industrial warehouses were they need to keep their inventory from melting.
Over the years I have played with this system and have found that if you use a smaller fan in conjunction with the one you already have, you can create some interesting effects.
For instance, if you place the smaller fan below the larger one (with the air flow going towards the larger fan) then you can create a nice “tornado effect” in the center of the room.
Now, keep in mind that a small fan pushing a lot of air still uses less power than the typical household light bulb. So, while this is great for a party, don’t expect the roof to lift off and the furniture fly around the room (unless it is really dusty).
Sources & references used in this article:
- Kit providing means for mitigating radon from a dwelling (JM Kilburn, JL Kilburn Sr, WL Stidham – US Patent 6,524,182, 2003 – Google Patents)
- Home Energy Article: A Systems Approach to RetrofittingResidential HVAC Systems (JA McWilliams, IS Walker – 2005 – osti.gov)
- Exhaust fan for bathrooms and the like (RG Penlesky, DW Wolbrink, KJ Jonas… – US Patent …, 1989 – Google Patents)
- Best practices guide for residential HVAC Retrofits (IS Walker – 2003 – osti.gov)
- Exhaust fan (IIRJ Luter, RA Bickel – US Patent 5,879,232, 1999 – Google Patents)
- A systems approach to spot ventilation. (PH Raymer – aivc.org)
- Cold Climate Housing News, Vol. 3, No. 1 (M Malkin-Weber, J Coulter, T Dixon, B Hannas… – Indoor Air Quality …, 2009)