poor air flow from vent question

[judgethis]

Our shop at work has two offices side by side on is 12x12 the other is 12x18 divided by a concrete wall. The larger room is 20 degrees cooler, the duct is about 15 feet long off the main duct and has good airflow. The smaller room is hot which is the office with the computers and I do al lthe paper work. The duct is about 30 feet long. The duct is about 5 or 6 inch round and well insulated. I thoght it was maybe clogged so I pulled open the access in the ceiling and only two bend. The air is cool coming out but not strong. I even took out the vent so there is no restiction still nothing. Even if I leave the door shut over night its still doesnt cool off.
Is there some way to force more air thru the duct. Maybe some type of fan?
I dont like having to sit at the computer sweating.

 

[portcity]

if the good duct doesnt have a baffle(damper), you could install one. Then you would be able to close it off some to balance the system. One only cost about $10-15 for round pipe, and can go between one of the joints. Then it has an external lever to adjust. If you want to spend the money, they have them also with electronic control. Another option is a duct booster fan. I dont know how these work though, northern tools sells some sizes.

http://stores.hvacexpress.com/-strse-322/manual-damper,-spool-damper,/Detail.bok
http://www.northerntool.com/shop/tools/product_200402935_200402935

 

[z28toz06]

If the system is sized correcty you should be able to cut the flow to the short run and balance the flow. You could put an inline damper or buy a new vent with a damper built in. All of my vents have them in the house, and I can adjust them right in each room.

 

[judgethis]

I like the duct boost fan. Dont know if the damper would effect it. We have one large duct about 18" running down the middle and all the branches come off that to each room. Thanks for the input.

 

[sammm]

Computers throw off a lot of heat and will really warm a room up. I know my home office (1 desktop and 1 laptop) is much warmer than the other rooms in my house.

 

[chevelle67]

Trace the ductwork back to the main truck line and look around. 98.9 % of all systems have balance dampers on each takeoff and a lot of people know they are there and will open theirs up or shut down others to get their office cooler. Look under the insulation if present as they are not large protruding levers and are sometimes hard to locate.

 

[trbomax]

Does your room have a return air duct? If not,maybe what you have is a circulation issue.

 

[judgethis]

I think you maybe right trbomx. In the larger cooler room I can put a piece of paper to the return duct and will hold it. In the smaller room I can barely feel the suction.
I installed a duct booster fan and helped a little bit. Its a little cooler than the shop and feel less humid but nowhere near what the large room feels like.
I may have to put a booster fan on the return side to help circulation.

 

[larry_g]

So in the large room try to block the return and see if your room increases its flow. Do both ducts come off the same plentum? Like said you have to balance the flows. Also look for some plugged filters as they can really reduce flow. Is some one leaving doors open that could upset the flow patterns?

lg
no neat sig line

 

[farmerscotty]

make sure no air leaks in the system......many times something will come loose and that makes all the difference in the world. I know on cold air returns on my furnaces I sell that happens sometimes......Go to Lowes and buy a pusher fan, and a 110 volt dial thermostat to put on the wall in the hotter room to have it where you can have it come on automatic if needed.

about 14 buck for the thermostat

 

[judgethis]

The shop I work at is aprox. 600ft by 300ft (maybe bigger) with 30ft ceilings. One section of it is offices which have drop ceilings.
In that section there is an 18" main duct that feeds the a/c to the offices. Thats from what I see. The feeds off the main is 6". The return between the two rooms are going to two different ducts. The one in the larger room is the last one on the one main duct. I dont know where the other one goes because it goes thru a brick wall and I cant see into the other side.
It was a quite a bit cooler today in th esmaller office. There has been less traffic going in and out of the office lately. I still might install a duct fan on the return side to pull out some of the hot air near the ceiling.
The larger room we can leave the door wide open all day and still is alot colder then the smaller room but it has a better airflow going on.
I dont think closing off the other vents would help much. Plus I dont think the other offices would appreciate it.
We even thought abought getting a thru wall fan between the large and small rooms.
Thanks for all your inputs slowly its improving.

 

[larry_g]

I dont think closing off the other vents would help much. Plus I dont think the other offices would appreciate it.

Thanks for all your inputs slowly its improving.

I would not suggest that as a fix, just as a trouble shooting tecnique. If you block their return and yours picks up a lot then you know there is a balance problem.

lg
no neat sig line