It is a one floor ranch. Air flow in all the vents in the basement are great. Half the vents upstairs work great and 1/2 I can only feel poor lukewarm air (when the AC is on) only when I take of the vent cover and put my hand 5 inches inside. My sister said some of it started when she cleaned the vents one time. It’s central air/heat.

EG: On one side of the wall, poor/little air flow BUT on the other side, spectacular air flow … help.
It is a one floor ranch. Air flow in all the vents in the basement are great. Half the vents upstairs work great and 1/2 I can only feel poor lukewarm air (when the AC is on) only when I take of the vent cover and put my hand 5 inches inside. My sister said some of it started when she cleaned the vents one time. It’s central air/heat.

EG: On one side of the wall, poor/little air flow BUT on the other side, spectacular air flow … help. Also, we regularly change the air flilter.

By: G A

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8 Responses to “Half the vents in my house have poor air flow. How can I DIY and fix?”

1. erinya23 on August 26th, 2009 5:07 am

   make sure pipes are tightly sealed and vents are in good condition…make sure stuff is clean and free from debris

2. Max J on August 29th, 2009 8:47 am

   There are “booster fans” that you can get at home depot and lowes, or at least they can tell you who to go to, unfortunatly you have to wire them up. I had them in all the rooms of my last place and it was nice because every room was the same temp due to increased circulation. Also ensuring you have clean filters is a good simple thing. When you change your filter, see if there’s dirt and dust behind it, if there is, you may want to have your vents cleaned, which is honestly best left to professionals.

3. christom95 on September 1st, 2009 2:02 pm

   I’m not a home heating/air professional by any means, but, here’s what I’ve done in my home. My livingroom vents are farthest from the furnace and that is where the thermostat is located. I got the same results as yours in my livingroom. My system has “dampers” in the air supply pipes. I closed them to 3/4 shut in the rooms closest to the furnace. Two of them I closed completely (still get enough cold air as damper is not 100%)The ones to the livingroom I removed completely. This allows more airflow to the room.
   Also: I know there are fans that can be installed in the weak lines that will push more air into these areas. They are activated by the thermostat along with the furnace.
   Hope this helps!

4. lee h on September 3rd, 2009 7:26 am

   close the vents to rooms you don’t go into often and close the doors (laundry room for example). My thermostat upstairs is in the master bedroom. Usually my room cools before my sons rooms at the other end of the house and the A/C shuts off. I kept toying with the vents in my room until there rooms were cool like mine. Now that side of the house is pretty close to the same temperature as my bedroom at all times.
   It sounds like whomever ran the ducts for the basement tapped into the same A/C ducts that were only meant for the main floor. A/C units are listed as tons. I have a 1700 square foot rental that I just installed a unit into. It was a 3 ton unit but I increased it to 3.5 tons. Either close all the vents to the basement or get a separate unit for each floor.

   Good Luck

5. hometech02 on September 4th, 2009 1:09 pm

   booster fans suk! they are junk unless u spend $$ to get good ones.. get your camera out and look down into the vents.. make sure they didnt come disconnected. also sounds like system is out of balance.. also there might be dampers down near the furnace that have been moved.. its also the way you balance it.. vents that exit closest to the furnace should be turned down (cut flow) if you have dampers look near the furnace for small levers on the ductwork.. if you look close enough you will see a flat end.. that flat end is in line with the damper. if the 2 rooms are sharing a vent.. close hers some

6. Bug Man on September 6th, 2009 5:50 pm

   You have a lot of variables here. There may be something blocking a portion of the ductwork. There may be dampers closed or opened that should be otherwise. There may be issues about how far one part of the house is from the source. Since you have access to the basement, go down and trace the ductwork. Take a magic marker and mark the vents that don’t seem to produce much air flow. Do they all seem to be on the same trunk (branch line) of the ductwork? If so, check the point where this line branches off the main and ten out to the first bad duct. There could be anything in there from that pair of undies you lost last year to Jimmy Hoffa’s corpse. (Are you missing any pets?) No obstruction? Try closing the vents or the dampers supplying the vents that produce lots of air flow. Does the flow improve in the bad areas? If so, it’s just a balancing issue. This is most likely since the problem started after someone took everything apart and cleaned…

7. luka on September 9th, 2009 7:54 pm

   partially close the vents going to the basement,you don”t need them open all the way due to basement is cool in summer,and open the upstairs or first floor all the way its called air distribution.

8. John G on September 11th, 2009 10:36 am

   Look for “balancing valves” which will be found near the air handler. These have the appeance of small handles attached to the side of the ductwork. They control flow to the vents they feed, and allow you “balance” flow from one place.

   Since you DO have strong flow from some vents, the problem is not the air handler itself. If no balalncing valves are found, best thing (only thing, really) is to close or partially close vents in strong flow areas, which will force more air into the sluggish areas.