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-   -   How many HVAC air intakes do I need in the basement? (

jeffs 02-20-2013 06:54 PM

How many HVAC air intakes do I need in the basement?
Upstairs I have an air intake register in every room. In the basement, there is only 1 air intake in the center of the basement. I want to finish my basement with several new rooms. Do I need to have intakes registers in every room in the basement?

nealtw 02-20-2013 07:12 PM

Welcome to the site. Pumping air in a room dosn't work all that well unless it can also get out of the room.

jeffs 02-20-2013 07:28 PM

Thanks nealtw, you make perfect sense

nealtw 02-20-2013 07:58 PM

I am sure there are rules for this that may change depending whether you do more cooling or heating. A little above my pay scale;)

Fireguy5674 02-21-2013 10:46 AM

I added a room in the lower level of my daughters home. It is a split foyer home with the garage under the bedrooms. We converted open garage space into a bedroom opening into family room on the lower level. I installed a duct into the ceiling for conditioned air and for return air I put a hole through the wall into the lower level family room. I covered it with a cold air grill on both sides so air could return to the furnace. It has worked well. Just another thought.

CallMeVilla 02-21-2013 11:12 AM

This is not difficult. To size the return air requirements for the basement (or any room), figure the area of each supply duct in the room and add them together. The return-air grill you use must have as much free area as the total area of the ducts supplying air to the room. The basic principle is to equalize the air pushed INTO the room with the air sucked OUT of the room.

Make sense?? :D

Also, make sure you seal the insulation flex properly and use long zip-ties to connect the ducting to the exhaust/intake boot. You do not want your return air sucking insulation back into the system. You also want a sealed system which has no leaks into or out of the rooms.

keepinitcool 03-05-2013 07:09 PM

Good advice here by everyone. Also if you are putting supplies in the ceiling of your basement, then put the returns as close to the floor as possible and opposite the supply diffuser. This will exchange the cold air on the floor with the warm air from the ceiling as it pulls it down and across the room. Also be careful of putting returns in basements if you have any open combustion equipment such as water heaters. If not enough combustion air is present a downdraft situation could occur which sucks the flue gas back into the house instead of sending it outside. Carbon monoxide detectors are a good idea in a home anyway. Hope this helps!

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