How do you vent a gas dryer? read this to stay safe5 min read

Gas dryers are more powerful than electric dryers and only require 110v of electricity. However, failing to properly vent a gas dryer can be dangerous and can lead to fires and even death due to carbon monoxide poisoning. 

Gas dryer installation should follow the International Residential Codes of exhaust ventilation covered in section M1502. This includes rules on vent material, duct size, duct length, exhaust termination, clearance to combustible materials, and the vent hood. Failing to vent a gas dryer properly is dangerous and can lead to carbon monoxide poisoning. 

Whilst venting a gas dryer is sometimes left to professionals, it’s actually a simple process. In this article, I explain the main principles of gas dryer ventilation and general guidance on how to effectively ventilate a gas dryer. 

Does a Gas Dryer Need a Vent?

Some people choose to use gas dryers due to electrical constraints within their house and the fact that they are more powerful and efficient compared to electric dryers. Whilst most dryers need ventilation, it’s particularly important to properly vent gas dryers. 

In addition to expelling heat, moisture, and lint, gas dryers release Carbon Monoxide as a by-product of combustion. I always recommend homeowners install a Carbon Monoxide alarm (on Amazon) as it can save lives.  

Carbon monoxide is odorless, tasteless, and colorless making it very difficult to detect. It’s also dangerous and can cause carbon monoxide poisoning causing symptoms ranging from headaches to death. Roughly 2000 Americans die each year due to Carbon Monoxide poisoning.

In addition to health concerns, the consequences of not venting a gas dryer properly include reduced air quality and lint being strewn everywhere. Lint is highly flammable and roughly 15,000 dryer fires occur yearly in America with the majority of cases being down to a clogged dryer vent. 

Both dryer fires and carbon monoxide poisoning can be prevented with correct ventilation installation.   

4 Things You Should Know About Venting A Gas Dryer

Within this section, I’ll cover building codes, where to vent your gas dryer, the type of ventilation, and what you can do if you can’t properly vent your gas dryer.

1. You should adhere to building codes regarding venting your gas dryer

Most homeowners and construction guidelines will focus on the International Residential Code M1502 which covers the rules and regulations on how to vent your dryer. 

In summary, the code covers vent material, duct size, duct length, exhaust termination, clearance to combustible materials, and the vent hood. I’d recommend you read the codes before planning your ventilation system and also bear in mind that building codes can vary by jurisdiction, so it’s essential to consult the specific requirements of your local building code authority or relevant regulations to ensure compliance with the applicable standards.

2. you need to ensure your gas dryer vents to the outside of the house

You should always vent your dryer, regardless of whether it’s gas or electric, to outside the building. Venting inside the building can cause health problems as well as being a fire hazard, and the consequences of not venting a gas dryer properly are more severe than electric.

I’ve seen some gas dryers vent into the garage, into the basement, or into the crawl space and homeowners will assume that this is as good as venting outside the house. However, venting internally causes the following problems: 

  • Fire Hazard: Gas dryers produce lint, which is highly flammable. If the dryer is vented into an enclosed space like a basement or garage, the accumulation of lint can increase the risk of a fire. 
  • Carbon Monoxide Buildup: Gas dryers produce carbon monoxide, a toxic gas that can be harmful or even fatal if inhaled in high concentrations. Venting the dryer into an enclosed space can lead to a buildup of carbon monoxide, posing a serious health risk to individuals in the area. 
  • Poor Air Quality: Venting the dryer into a basement or garage can lead to poor indoor air quality leading to mold growth and unpleasant odors.
  • Condensation and Structural Damage: The moisture expelled by the gas dryer during the drying process can condense on surfaces within the basement or garage. This condensation can lead to dampness, mold growth, and potential damage to walls, ceilings, and stored items. 
  • Compliance with Building Codes: Venting a gas dryer into a basement or garage probably won’t comply with local building codes or regulations.

3. the type of ventilation required for a gas dryer

Gas dryers require venting to the outside of the building. The venting should be made of metal pipes four inches in diameter. 

Rigid metal vents are safer than their flexible plastic and metal counterparts, as they trap less lint, don’t need frequent cleaning, and allow for better air circulation. Flexible ducts are more prone to being crushed, hindering airflow and leading to the dryer overheating, and possibly starting a fire due to the lint build-up.

You can use a 4-inch flexible aluminum foil duct that is UL 2158A listed and marked for safe dryer venting. Look for a product made from heavy-duty, fire-resistant aluminum foil with a high-density, corrosion-resistant wire helix. 

4. there are viable alternatives to a gas dryer

As I mentioned earlier, many people choose to use a gas dryer due to its superior performance, the lack of adequate electricity in their homes, and the fact that it may be cheaper to run. However, if, after reading this article, you have doubts about your ability to safely vent your gas dryer, I’d highly recommend looking at some alternative options.

Both condenser dryers and heat pump dryers offer the advantage of not requiring external venting. 

A ventless dryer doesn’t vent to the outside. Instead, it recycles the air inside the dryer and filters out lint.

Bosch Ventless Dryer
I found this 4 year old ventless dryer on Facebook Marketplace for $400.

The hot air from the clothes is condensed in an internal heat exchanger and converted into water. These dryers are highly energy efficient but usually take longer to dry clothes than regular dryers and have a smaller capacity.

How to Vent a Gas Dryer 

Venting a gas dryer is a relatively straightforward task that requires some elbow grease and some supplies. They include:

Here are some steps providing general guidance on how to vent a gas dryer. Note: this is meant as guidance only and should not be taken as a substitute for professional advice. 

Step 1: Choose the Shortest Route for the Vent

The first step when installing a new dryer vent is to map out the shortest possible path for the ductwork. Ensure the route is horizontal and has a pitch of ¼ -inch per foot to the outside.

For basement installations, use 90-degree elbows to create a vertical ascent that leads to an outside wall. This will help prevent moisture from settling in the pipe or flowing back to the dryer.

If your washer and dryer are situated in an upper-level room, it might be possible to vent through the roof, depending on the model of the dryer. You can check the manufacturer’s guidelines to make sure.

Step 2: Drill a Test Hole In the Rim Joist

Mark the middle of the rim joist and use a ¼ -inch bit to drill a test hole. Find the hole outside and check it for any obstructions.

If the hole isn’t in the right place or the cap doesn’t fit correctly on the siding, you can change it. If it appears to be off, you can fill it and start again in a different spot.

Step 3: Adjust the Hole to Fit the Siding and Drill the Vent Hole

Position the hole so that the top of the vent cap is aligned with the highest part of the lap siding, then separate the vent cap and duct for easier measurement. Bore a 4-¼ inch hole using a hole saw.

Step 4: Drill Through the Rim Joist and Install the Vent Cap

Stop drilling and pry out siding and sheathing from the saw as you progress. Carry on with your cut through the rim joist. Insert the vent and screw the cap to the house. Push a foam backer rod into deep gaps, then seal around with acrylic caulk.

Step 5: Cut the Vent to Length

Use tin snips to trim the straight sections to the right size before joining the pieces together. Put on leather gloves before cutting the metal edges because they’re sharp.

Step 6: Close the Seam on the Vent

Line up the seam edges of the duct, then starting from one end, press the edges together while gently pushing them down.

Step 7: Tape the Elbow Joints and Attach the First Vent Section

Connect the crimped end of the first elbow to the first straight section of the dryer and secure the joint with metal foil tape. Put the first piece of ductwork on the dryer and press it up against the wall. Measure the other components, cut them to size, and connect them.

Step 8: Install the Other Vent Sections

Insert the last elbow into the ductwork piece running up the wall, secure the crimped end of the elbow into the duct cap section, then fasten it with tape.

Step 9: Secure the Vent to the Wall with Straps

Secure the duct to walls or ceilings every 6 to 8 feet using a pipe strap. Wrap the strap around the duct rather than screwing the strap to it.

Step 10: Turn On the Dryer

Plug the dryer in and switch it on. Go outside and check if the vent flap is opening and the vent is functioning properly.

This Old House put out a fantastic video on how to install a gas clothes dryer that I thought you’d find helpful: