AVS Forum banner
Status
Not open for further replies.
1 - 15 of 15 Posts

·
Registered
Joined
·
7,746 Posts
Discussion Starter · #1 ·
Well I'm looking to cool my room a little better.I moved the return higher on the wall for summer AC. I have two runs to the room for heat and AC.The room is kinda far from the furnace.


I'm going to put two inline 6" duct fans as my cheapest solution.They are 120vac.They move about 350cubic feet a minute or something.


Do I run them off the 120volt line to the furnace blower motor or do I do a relay with separate power to the fans.The motors are tiny and only consume about 1/3rd of an amp each.


Thanx KG
 

·
Registered
Joined
·
4,088 Posts
KG, this is something that many of us struggle with. I live in the Central Valley in Ca which like much of the nation has been going through a heat stroke. Our daytime high temps have ranged from 98-106 for about the past month now. I don't think we have had any days lower than 98 in there that I can remember. Great for sitting out by the pool, terrible for being in your home theater, especially if it is on the second floor and has outside exposed walls.


What I did was have three registers installed (all supplied with 8" ducts) and two returns (both with 8" ducts as well). While this helps more than the old way, there is no way it is a good solution. Once you put people in the room and turn things on, it gets warm. You don't feel it as much if you are sitting in the seats, since the supplies blow directly on the seats, but as soon as you move out of those cooling sweet spots, you feel it.


Adding some 6" in-line fans to the existing duct-work probably won't do anything for you, since you are just going to try to push more air than the system can handle. Your best bet would be either a dedicated HVAC system for the room (not really possible in my case) such as a mini-split system or having your current system zoned.

I had the zone option quoted for me and it would have been $3600 to get it done. I decided to have the $600 option done, which was the second return and the third register.


I would have been happier if my builder would have done the right thing and set the house up on a zoned system originally, or at least put in two cooling units, since the house is on the border of what the current system can handle.
 

·
Registered
Joined
·
1,070 Posts
The consensus from the HVAC pros is that inline fans do nothing but waste electricity because the CFM capability of the duct is in its size, length, and number of bends. The one thing you can try is to close off the dampers on the ducts going to the rest of the house very slightly to increase the main plenum pressure. Doing so makes your problematic runs the path of lower resistance and may help. If that doesn't help, I would call in the pros.
 

·
RETIRED theater builder
Joined
·
35,574 Posts
Bobby I got to take issue with your statement. "The CFM capability of the duct is in its size, length, and number of bends". You left out one important part and that is static pressure at the head and end of the duct. If the pressure is higher there will be a greater CFM flow.


Now whether or not those in-lines can make a noticible enough difference is uncertain. The cheapest thing to try would be to double the number of supply and return vents off of the main trunk to this room. Or double the diameters of the existing ducts (assuming the take off diameter and grill sizes are also increased)
 

·
Registered
Joined
·
7,746 Posts
Discussion Starter · #5 ·
This is a first floor room.I have a two zone system now.The upstairs is separate from the down stairs.It does a great job of cooling the upstairs at night and during the day.


I will get in touch with the guy who installed it and see if my room can be zoned for a third zone. The video room is about1890 cubic feet.


There is no problem in the winter because of people and equipment warming the room up.The warmer the better.


I third zone with eight inch runs would be sweet.I wonder if the motor would work full speed or slower for the smaller zone.Hmmmm.


Thanx guys, misery loves company.
 

·
Registered
Joined
·
163 Posts
I just ripped one out I installed last year - not much of a noticeable improvement and it was very loud. If you do install one, make sure its far away from your theater so it can't be heard.
 

·
Registered
Joined
·
7,746 Posts
Discussion Starter · #7 ·
Well I gotta watch LOTR (ROTK) saturday and I'm going to be cool one way or another. This is a standing AC unit given to me a couple years ago by a friend.With a little ol' DIY I'm pumping cool air in one of my two ducts. It took about an hour to cool it off.I would like to get through all 4 hours without sweating.Just a temp fix.
 

·
Registered
Joined
·
164 Posts
I have a couple of duct fans plumbed into the supply lines for two of our upstairs bedrooms. They do help, but they are loud. There is no way the noise would be tolerable in a theater environment. Unless you turn them off while actually using the theater, I'd look for an alternative solution.


-Dave
 

·
Registered
Joined
·
6,327 Posts
I have a booster fan right now that I plan to use for my HT.

I have access to it so if it is to loud, I can move it or find a way to deaden the sound.

I know two people with dedicated HT's who use a booster fan on their return duct with no other form of zoning, mini split or what ever and the system works beautifully.

I don't see why it wont work on mine.


Craig
 

·
Registered
Joined
·
7,822 Posts
Loud. Too loud.


I put a little 4" duct fan in the attic to draw heat from the equipment alcove. It claims 52 dB on the box, but they don't specify how it was measured. Must have been from a city block away. It is too loud to be used - about 60 dB in the room.


There are quiet inline fans, but I haven't found one for
 

·
Registered
Joined
·
6,327 Posts
Oh, buy the way, I forgot to add in the above post that the duct fans the two people used can not be heard in their theaters.

I am expecting similar results.


Craig
 

·
Registered
Joined
·
7,746 Posts
Discussion Starter · #13 ·
The DIY super cooler worked.What I'm going to do is this...leave the two supply lines in and just add the super cooler.I not only have a return up high but I have a return for the hushbox that pulls warm air through the box from my rrom to the basement.


I now have to find a spot for the super cooler for a permanent install.With the return for the hushbox that helps equalize the preasure of the supercooler.Who knows.....
 

·
Registered
Joined
·
7,822 Posts
By "supercooler" do you mean the little stand-alone AC unit?
 

·
Registered
Joined
·
7,746 Posts
Discussion Starter · #15 ·
Yes.It has a squirrel cage type fan that has some real power.The permanent in stall will be a shorter lenth so I might get away with the unit running on low instead of high.It was a little noisy during quiet moments.
 
1 - 15 of 15 Posts
Status
Not open for further replies.
Top