How long can a bathroom exhaust fan duct be?

Generally a 4 inch flex duct can carry a fan exhaust for up to 25 ft. Most codes require that.

What size duct do I need for bathroom exhaust fan?

When sizing a vent fan, a factor to consider is duct size and length. Most 50 CFM fans will run well with 4-inch round duct. But as you get up into the higher CFM fans, duct size will have to be increased to 5- or 6-inch round duct.

Can you vent a bathroom fan with PVC?

PVC piping is an excellent material to use for venting your bathroom fan as long as the correct type of pipe is used. PVC creates a better seal than metal, so you won’t experience any problems with leakage as you could with using metal ducting pipes.

How long can a duct run be?

If you choose well, you can be at 10 or 20 feet of effective length. If you choose that smooth mitered elbow, however, you end up with 75 feet.

What is code for venting a bathroom fan?

Section 1203.4. 2.1 of California’s building code requires all bathrooms with a bathtub, shower, spa or similar fixtures to be ventilated by an exhaust fan. The fan must be Energy Star-compliant and vented to the outside.

Can you use 2 inch pipe for bathroom fan?

A 2″ pipe would carry less than 25% of the airflow that a 4″ pipe would carry, and probably wouldn’t be sufficient for any size shower (unless you used some sort of high-pressure fan, which isn’t what a bathroom vent fan would be).

Does bathroom fan duct need to be insulated?

The bathroom exhaust duct should be insulated when it passes through an unconditioned space. This means that the temperature of the space is not controlled. Most exhaust ducts run through an unheated/cooled attic and must be insulated to prevent condensation inside and outside of the duct.

Can you use dryer vent duct for bathroom fan?

A bathroom fan and a dryer should never share the same vent. International building code states that dryer vent exhaust systems must be separate from all other systems and must expel moisture out of the house through a dedicated vent. This is because of the potential hazards associated with improper dryer venting.

Does length of duct affect cfm?

Texas A&M did a study on the effect of flex duct not pulled tight and the results are astounding. In my article on this research, I showed from their results that a 6″ duct moving 110 cfm when pulled tight will move only about 70 cfm with 4% linear (longitudinal) compression and about 40 cfm or less at 15% compression.

Does length of duct matter?

The size of your heating and cooling equipment dictates the size of your duct work. When your home was initially built, that was the easiest time to ensure the ducts were sized and installed correctly. However, just because your duct work is “out of sight” doesn’t mean it should also be “out of mind.”

How do you calculate effective duct length?

The total effective length (TEL) equals the measured length from the farthest supply outlet, through the equipment, and to the farthest return outlet—plus the equivalent lengths of all turns and fittings. Friction rate gets calculated based on the pressure drop per 100 feet.

How do you run a bathroom exhaust duct?

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Can 2 bathroom exhaust fans be vented together?

Well, you can’t! You’d often blow air from one bathroom into the other, and local building inspectors wouldn’t approve it. But while you can’t have two fans with one vent, you can make one fan and one vent serve two bathrooms.

Is it against code to vent bathroom into the attic?

The Code of Bathroom Exhaust Fans

Air shall not be exhausted into an attic (except whole house ventilation), soffit, ridge vent or crawl space.

Can you tie bathroom exhaust into plumbing vent?

The answer is no way! Sewer gas is explosive and could settle back into your exhaust fan which has an electric motor that is not rated for explosive gases. You’re now not at code for the sewer or the fan.

How many fixtures can a 2 inch vent handle?

The Plumbing Code states that a vent can handle 24 fixture units. A bathroom sink of 1.0 F.U., a bathtub of 2.0 F.U., and a shower of 2.0 F.U.

Can a toilet and sink share the same vent?

Wet venting is most common in conjunction with toilets and sinks; the drain for the sink is also the vent for the toilet. It can also be used for a variety of other applications but due to the following rules this is the most convenient and common situation to run into.