www.heyokasolutions.com

A laminated sheet with provides pressure relief solutions for homes that have central returns.  This item ships via USPS First Class Mail for the fixed rate of $3.00.  Please provide a ship to address that is recognized by the USPS.  If you need to change this method, just call 866-389-8578 to place your order!

Formulas for:

• Through-the-wall openings;
• Slot or door undercut;
• Jumper ducts using flexible ducting;
• Notes on using high/low grilles and wall sleeve;
• What if you don't know the supply airflow?
• A table if you don't want to do the math!
  

It is certainly less expensive to use a central return than it is to install return duct runs to every room.  The problem occurs when room doors are closed and that's what they are there for.  The room with the supply will be pushed positive, forcing conditioned air into the building system.  The room with the return will be pulled negative, sucking hot humid air into an air conditioned space.  This is a formula for disaster.  This sheet provides the formulas that are necessary to relieve the pressure in the room. 

1. How big should the grilles be for a cut straight through the wall?
2. How much should a door be undercut to keep the pressure under 2.5 Pascals (building code in many states);
3. How bit a jumper duct do you need to use?
4. How can you estimate the airflow if you don't have a way to measure it?