Running Ducts Between Floors

Ducts should be able to run between studs in the wall and then turn into a joist bay the space between two joists.

Running ducts between floors. We ve recently had a slight moldy smell and water on the 1st floor ceiling. It turns out that the air conditioning ducts in that space are covered in condensation which is. It might be worth mentioning also that before any duct sealing is performed it might be a good idea to perform a quick static pressure test of the duct system to see if the duct system can handle being sealed. User 6759891 posted in energy efficiency and durability on february 10 2017 05 05am i m in the process of renovating an older bungalow home in climate zone 7a.

The most common size duct used is 14 in. This size fits just between most floor joists. Another method which isn t shown in that paper from nrel is to put the ducts in a conditioned crawl space as shown above. The fourth shows them in the attic sort of but below the building enclosure with some help from a special type of truss.

Many times the leaks in an undersized duct system are the only thing keeping border line airflow rates from falling off the cliff. Also make sure to use hvac tape and seal all of the joints between duct segments. No air should be able to penetrate the ductwork and the joints are a natural weak point. The third shows ducts between conditioned floors in a multi story house.

Running a duct from the first floor to the second involves creating a hole in the main duct and attaching new duct work that terminates in a floor level heat register on the second floor. First building codes in many areas require that the cold air return line gets external insulation and therefore you will need to leave a gap for the insulation around the duct return line. We have a 2 floor house built in 1978 in the dc area which is hot and very humid in the summer. It currently has an unfinished basement but i am in the beginning process of retrofitting this.

The insulation you use to wrap your ducts should leave no gaps and be at least two inches thick to work effectively at reducing or eliminating condensation on ductwork. Running a metal cold air return duct between studs requires knowledge of both hvac systems and the components involved in framing. Sometimes the best route for a flexible duct run is up and over an obstruction. Occasionally we need to access the ducts between the floors to improve the airflow.

Here are several ways to access ducts. One of the upstairs closets has a hatch in the floor that lets us look in between the lower ceiling and the upper floor. But without proper support ducts can develops sags or kinks that reduce airflow 4a 4b. Add a false return grille cut an access hole in the ceiling of the first floor in a central area to gain access to the ducts.

To prevent problems use saddles or straps to support at regular intervals 4c 4d follow the manufacturer s instructions but in case they get lost here is a list of best practices for.