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If your vent is too long or has too many twists and turns, it could easily trap lint and become a fire hazard.
In this article, we shall talk about the former: How long can a dryer vent be (apart from lint problems, your dryer could have persistent performance issues if it is longer than recommended).
So, what is the dryer vent max length?
Read on for a comprehensive answer.
How long can a dryer vent be?
According to (InterNACHI-International Association of Certified Home Inspectors- the maximum length for a dryer vent should not be more than 25 feet.
Besides, a vent should be as straight as possible….
To be clear, the maximum length should be reduced by 2.5 ft for each 45-degree bend plus 5 ft. for each 90-degree bend(a 90-degree angle) in the vent.
In a nutshell, the shorter (and straighter)the vent hose is, the better will be your dryer’s performance (and you’ll certainly have fewer lint issues).
Additionally, the duct should be a minimum nominal size of 4-inches in diameter and shall have a smooth interior finish.
I must mention that it is best you check the code requirements for your area (and manufacturer recommendations too) if you’re not sure about the max dryer vent length.
Speaking about the manufacturers recommendations, I have read in a couple of dryer’s manuals that a run of even up to 65-feet is acceptable (in certain conditions).
In fact, most codes tend to have an exemption saying you should follow your dryer manufacturers recommendations if the manual permits a longer run.
How long can a dryer vent be? –Related important questions answered
What happens if your dryer vent is too long?
When your vent is too long than recommended, your dryer will probably be taking extended drying times.
This tends to happen If the vent is too long and additionally winds behind the dryer- because it could be pinched, folded over (on itself), or crushed, which reduces airflow.
You perhaps, by now, know that it can cause lint to start building up.
Can you run a dryer vent straight up through the roof?
It is not advisable to run a dryer vent up straight through the roof.
Well, the higher your vent has to go, the longer the air must travel hence the less the airflow.
Put another way, going through a roof typically requires more power, meaning a booster fan could be necessary.
Something else: All the lint that would be coming out of the dryer won’t even have sufficient force(to blow it upward) and out of it’s exhaust so it will just piling up!
So you should vent your dryer through a wall (ideally) to the outside.
But if you must go through the roof, the vent needs to be solid metal(out through the roof) and a flexible metal(if necessary)from your dryer to the connection.
And you will likely need a booster fan!
Quick Note: According to code, dryer vent should not go through roof- It clearly says that Venting must be done down (under the house) and then out the side(at the short-est run) and done using rigid duct.
What you need to know about dryer booster fan
A duct booster fan can help if you have an overly long vent.
A good example is when your condo’s layout forces you to have the dryer a significant distance from its outside vent, causing the dryer to be taking forever to dry out your clothes.
The accessory helps out by enhancing airflow, which in turn allows the appliance to work easier and faster.
So clothes dry faster while using less energy-and keeping the duct nearly lint free- once you add it.
What happens if dryer vent is not connected?
Well, it’s not dangerous, by its very nature.
However, when you use your dryer with the vent disconnected, it normally blows an incredible amount of moisture/steam inside your laundry room(at least).
Not only is that not nice but it can cause mold problems etc. – You can try to tape it up(apply the tape to hold it on) as a stop gap remedy but you have to have the ducting fixed properly urgently.
Keep in mind that if you’re talking about a gas dryer, then it could be a terrible idea.
You see, it won’t fully combust the fuel, so you could harm yourself with the resulting carbon monoxide(particularly if it is vented into enclosed space)..
Dos and don’ts when installing a dryer vent
- To fasten drying, add a booster fan to your dryer vent especially if it is going through the roof.
- As much as possible, keep your exhaust duct as straight and short as possible.
- Do not use duct tape to connect venting materials- These tapes dry over time majorly due to temperature change, which creates gaps in the joints(of the vent). For starters, the correct tape to use for ducts is, for the most part, aluminum tape.
- Never use screws or bolts to secure your vent joints- The reason is screws and bolts act as lint collectors inside the vent wall so they can increase the risk of fire.
- Never use cages or screens to prevent pests from entering- When you use pest cages or even screens, lint can again build up, creating a fire time bomb. Dryer vents should instead have a flap (not a screen).
- Do NOT use plastic or foil-type vents- they are a fire hazard too(they heat up-and melt- and they can start on fire). Also, lint sticks(to the inside of vinyl ducts) so it often builds up way faster.
How long can a dryer vent be? -Recap
A dryer vent should be about 25 feet (max) in length.
That is because a longer than recommended dryer vent can make your dryer take longer to dry (mainly from the reduced airflow).
Also, too long vents can encourage lint buildup, which we all know can be a huge fire hazard in our homes.
Don’t forget to look up the code (and read the manufacturer dryer vent length recommendations)- these two should guide you properly, if you’re still unsure.