Need Help w/ Central Air Conditioning
 

So the hot summer is coming, and the problems are starting back up with the central air conditioning. We have a 4 bedroom 2 floor house. My room, the room across the hall, and the kitchen all get lots of A/C, the other bedroom, and all the other downstairs rooms get moderate A/C, and the Master Bedroom gets next to nothing, so in the summer, when the thermostat is set to 72, my bedroom is 60, the moderate rooms are around 72, and the master bedroom is at 80. So what ends up happening is to get the master bedroom down to 72, the moderate rooms go to 60ish, and mine to 50-55ish!

So does anybody out there who knows a thing or 2 about central air conditioning? I was thinking getting a dozen or so 6" PC fans, and installing them in the ducts, but IDK if that'll work. I just need to get this air thing balanced out.
Please help!

make flow limiters in the ducts, We did it at my house to even out the AC. Ply wood works.

That's a poor mans way of doing it. Just make certain you use something that isn't going to be a fire hazard or a bug magnet.

Another thing to check is to see if you can find access to the ducts and insulate them as good as you can. Heat loss/cold loss is a big factor in what you are describing. My guess is that the master is the farthest from the AC unit? And its possibly the room that is most exposed to the afternoon sun? You may want to consider adding a secondary AC unit, such as one of the portables, or a window unit to help.

Flow limiters

http://www.cookeindustries.co.nz/pdf...5-9.2-EN-5.pdf

The vents in my house have little adjustable flaps in them. So, for the hottest rooms (generally the ones with the most windows), I open them all the way, and partially shut them in the coldest rooms.

a poorly designed A/C system will do the exact. i feel like your is just of an extreme:neutral:

the "correct" way to fix it is to redo the ducting. Getting rid of the older circle or box style splitters and using triangle ones. Trying to even out the lengths of ducting as much as possible without wraping.

BUT the duct limiters should work...but is a quick and dirty method. You will gain some heat energy from the lack of "good" flow

This might help..
What I did was install a couple ceiling fans.

the tiny flappy things are not enough blockage, and we do not have the time/skill to correctly reduct the house(mabye come october...), so it does seem that the limiters are the way to go... but im still open to more ideas!

Plywod can fe shaped into any size you want.

I think the flaps Brian was referring to aren't the ones on the vent, but in the duct itself (there just a built in flow limiter). You just close off the lever on the colder rooms and open it up on the hotter ones. My house is the same way, and even with all of them closed for the most part except mine, my room is still quite a bit warmer than the others since mine is the farthest from the A/C unit. Get up in the attic and see if theres any levers on the ducts right before the vent.

The limiter flaps installed right at the distribution box (main plenum) will most likely be the best bet. Properly sized ducts and registers will cure the issue. I am sure a competent a/c guy can figure it out for you. At least your a/c seems to be working well.

Resident Tin knocker here.....There not called flow limiters! Volume dampers is the proper terminology. Sorry I gotta be a smart ass when I can. There has been some good advice so far. Linc said it best, istall the volume dampers as close to the main plenum as possible, they will make the biggest difference there and create the least amount of noise in the rooms. If the ductwork isn't wrapped with insulation that would also help, both summer and winter. The dampers that are part of the registers are really only to shut off rooms that you don't use, using them to limit the volume of air will create a lot of noise and have less effect getting the air to the other rooms. That is why you want to install them as close to the furnace/heat exchanger as possible.

What do you think of the flexi ducting? I have recently (well in the last 3 years or so) installed a few systems and used the flexi duct in all of them. Seemed pretty good, and was super easy to do. I could easily do a single story house in a day if I was swapping out the old ducting for this... As long as someone could figure out the correct sizes for the various rooms...

Being in the Facility Management and Construction Management business I can tell you e-revonut is right on. Your best bet is not to guess at it yourselves but to hire a competent AC guy to help you out. Your system needs to be balanced and like linc was talking about everything needs to be sized correctly.

In my personal experience the best are guys that have been in the business for 20-30 years and own their own small business with 3-10 employees. The big companies can do the work, but most of the time at a very high premium.

Flex is not good for full runs. There is a lot of static loss with flex, a lot of friction on the air passing through because the sides aren't smooth. Generally the most flex I'm allowed to put at the end of a run is 6', sometimes the specs for a job call for no more than 3'.