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4" or 6" Ducts. Which is better? I just had Central A/C and Heat installed and most of the rooms connected to the end of the Trunk line barely push out any air. There are currently 5 Registers/supply's (Cat Room, Bathroom 1 & 2, Computer Room, Baby Room) connected to the end of the trunk line, all seem to be 6" ducts. The lines in the beginning of the Trunk (my bedroom) pump out an enormous amount of airflow, so much that I leave the vent closed.
my question is, When do i use 4" or 6" ducts? I believe the beginning of the Trunks have 6" and 7" and towards the end are all 6". I need to increase the airflow at the end of the Trunk Line (the 5 registers).
I got two different answers when i went to Home Depot and Lowes. One said I need 6" ducts at the end while the other says to use 4" ducts because the airflow is the weakest and I am just moving cold air.
Do I leave the 6" at the front and change all at the end to 4"?
Is using a 6" to 4" reducer the same or do i have to replace the actual piece at the trunk.
Here is a PPT drawing of my home. Please note that the Trunk/Unit are actually the same but since I have a crawlspace running alongside my home, It was just best to draw it twice. Also, it may look reversed but the 1st page is drawn horizontally and the 2nd vertically. Just picture the crawlspace in your head to line up the direction in your mind.
I am not concerned about the bathrooms, primarily the Computer Room (1st floor), Living Room (1st floor), Main Bedroom (2nd floor) and Baby Room (1st floor).
My beams run in the same direction as the arrows for ductwork. If you need size dimensions, I would my house is roughly 35 feet by 60 feet. 35 feet is the direction of the arrows.
I would prefer to reduce the Main Bedroom and increase flow to the Living Room (directly below Main Bedroom (2nd Floor) and Computer/Baby room (Below Cat Room on 2nd Floor)
Ohh this is my home lol my oil heater went so it was going to cost just as much to replace and move my oil furnance as it was to install Central Air and Heat.
At first, I had them come back because i was barely getting anything out of the end of trunk registers. They used so much Flex, We literally cut off about 6 Feet of Flex at each register. I thought that would solve the problem, it did make it better, but not efficient.
I didnt draw Returns but there is a huge return in the hallway on the 2nd floor, One in the Cat Room, One in the Main Bedroom, and One in teh Living Room.
If you need to know the model its a 3 Ton Goodman 16 Seer w/ Heat Pump and I believe they did a 4 Ton blower? Not quiet sure.
i believe all vents are 12"? and 2 x 10" vents in the Living Room.
I already have the ceilings opened cause the electrician cut one of the ducts when he ran wiring for my new electric water heater. I also already removed the flex from the Baby Room and have both 4 and 6" hard ducts ready to install. Plus since Im doing it, I am going to properly insultate each piece as i run them.
As for getting the installer to come back... well, thats what i get for going with the cheaper company. Its just one of those things where you say to yourself, i dont want to deal with these people anymore and if you want something done right, gotta do it yourself heh
Yah i see what your saying about reducing, Forgot to put that in the drawing but there is one point, about halfway where it looks like they reduced it a 6"? Unsure of amount but it does get a bit smaller and stays that width until the end of the trunk
So I guess your saying leave the ones at the end as 6"? I dont mind shrinking the ones in my bedroom to a 4" if that will increase airflow. I was also debating on removing one Register from my bedroom since that room gets VERY hot
I bought all the necessary pieces of 4" and 6" I just want to try to make the airflow better at the end heh.
Another option is installing one of those in-duct Fan things? Or should i just leave it all as is and just insulate the duct pieces I can get to that run between the joists. the ceiling is already open
ok, its a 3 Ton Heat Pump and I believe the Blower is set to 4 ton. As for the Main duct, if you mean the Trunk it is Rectangle. and wrapped in some insulation cover.
All Lines to registers were mostly Flex Duct but they came and replaced a lot of it with the hard metal duct and removed excess flex at each register. The whole house is only 1700 Sq feet i believe.
All are 12" Registers I believe except the two in the living room which are 10"
I am going to run upstairs and measure the size of the rectangle trunk and where it shrinks down a size. brb 2 min.
GOod thing my walls are still down. Had wood walls upstairs and i tore it down because i was redoing all the drywall & electrical.
ok so the Trunk is 9 Inches High and 16.5" wide. Roughly right where the stairs are on the 2nd floor is where it shrinks to 9" high and 12" wide
Are you saying that the first drawing you provided is correct or an example of an incorrectly one? Do you think that the solution really is to just shrink the main trunk line down a bit more? And if so, how easy is that lol
Just measured the main trunk start and it is 20.5" wide, 9" high. Ill have to go scout to see where it drops to 16" wide and 9" high
So basically your saying the problem isnt necessarily the actual duct work, its the trunk. So leaving them all at 6" should be sufficient?
Right at the start of the trunk there are 3 lines coming off it (2 in Family room + Kitchen)
and it looks like 4 lines coming off the trunk when it is 16.5"
and 5 when it is 12 " wide
Give me one sec, I kind of understand where you are going with this. I just want to get the total length of my trunk and the distance between the trunk and register.
brb 1 min
since I know im taking up a lot of your time. If i was to give you a $40 tip and provide you with the exact length of my trunk (or max space available for the trunk lengthwise) and provide you with the exact distance from the trunk to the registers. Could you provide me with the trunk dimensions and where I need to decrease it? Not sure if you have that book Manual D - Residential Duct System. it doesnt have to be perfect, just your guestimation would probably be better than what i have now lol
Frankly, since my walls are open, me re-doing the trunk would be a lot easier than me trying to redo all the ductwork to each room. I have full access to 85% of the trunk except at the end there is about 4-5 feet I would have to crawl to but is still accessible.
I can just completely remove the trunk and make adjustments to it and just reconnect the registers/supplies since those pieces will be there already waiting to be connected
I can always run a trunk within the beams horizontally if you think that is better . My house isnt that big and with the way the crawlspace is, Ideally it would be nicer to just keep 1 trunk and leave the register/supply ductwork that is already in place.
As you can see by the drawing, that one trunk locations basically directly hits 8 (Main Bedroom x 2, Living Room x 2, Family room x 2, Computer room, Cat Room) of the 12 registers without running a lot of ductwork.
The only ones with more than roughly 4-5 feet of duct are the Kitchen, Both Bathrooms and Baby Room.
Ill go measure while you are eating.
Whoops Sorry, was doing the PPT. http://www.mediafire.com/?ammd0gidord
Basically the crawlspace runs alongside my house and is roughly 3 feet wide by 3 feet high. Some people use it for extra storage space but its pretty much unfinished and kind of like an attic crawlspace but running alongside my house on the 2nd floor. Why its there, is beyond me lol I actually have the crawlspace running along both sides but I removed the irrelevant one because it is hard to get to if we were going to run ductwork.
The Indoor part of A/C Heater Unit is in my attic which is directly above the Family room. The Trunk is connected to that unit and runs into the crawlspace. Both pieces are located on the 2nd floor. So that one trunk line does both 1st and 2nd Floor.
On the 2nd floor, all the registers and supplies come out of the top of the trunk to feed the upstairs registers. All of the ones downstairs come out of the bottom/underneath the trunk and in my Joists to get the the rooms like the Baby room, 1st floor bathroom, and Kitchen. All other registers - Computer Room, Cat Room, Main Bedroom, Living Room are literally either 2 feet above or below the Trunk Line. The 2nd Flr bathroom Basically shoots across from the trunk to the bathroom by utilizing the attic. And the Family room (1st flr) is literally below th attic so they just ran 6" ducts in the attic and just cut holes to install the register.
I think the confusion is coming in because the 2nd floor was drawn Horizontally and the 1st floor the other way but if u use the Trunk as your point of reference just turn one page so that they are literally on top of each other.
hopefully this one makes a little more sense. I rotated the second page so you can basically see how they line up
Sure, thanks again. XXXXX mistaken, i thought they said my blower can go up to a 5.5 ton blower but im not 100% on that. You would think this house should be easy to heat since 80% of the vents are right above and below the trunk. There are really only 4 vents that have to travel any distance (Bathrooms, Kitchen, Baby Room)
the Family room ones I was probably going to move to the other side of the wall to eliminate the extra 10 Feet of duct they put down so those will only be about 5 feet directly to the left of the start of the trunk.
I have to run to walgreens to get baby detergent. If you answer while im gone or need any additional info, I can text that from my phone since it sends me a message.
Hopefully its just the trunk that is causing the problem cause it would be nice to return the $400 worth of duct stuff i bought and just get a newer, bigger trunk plus materials to reconnect each supply back to the trunk
Gotcha. Thanks a bunch but I just want to make sure i understand this diagram.
So where you indicate 6" or 7", I know that is pretty straight forward for the actual duct work but when it comes to the actual connection between the end of hte duct and the register, do i need to specifically look for a 7" register or at that point, can i use a 7" to 6" converter etc.
For the trunk, is the 1200, 790 and 410 the CFM that is remaining at that point? or does it mean something else. Does how long each section is matter? Or can i pretty much just wing it from the point indicated on teh design or after it passes the last register for that group.
Im assuming the 10x24, 10x15, and 10x9 are the sizes in Inches. Dumb question but, is there a specific name for Trunk so when i go look for it in Lowes or Homedepot do i need to call it something else?
And the 120, 110, 100 etc I assume that is the umm Feet per Minute or CFM each register should be pumping out?
When you mention dampers, I briefly read through that link you posted, so basically im putting in Dampers not so i can change them around freely whenever i want but to balance out the airflow throughout the entire system? And basically I can close the wall up cause i wont need to mess around with the dampers once it is set?
And the last dumb question, does it really make a difference if I have all the supplies coming out of hte side or top or should i really have it come out of the bottom for all the 1st floor registers?
Thanks again for all your help and advice, now I just need to go return two truck fulls of duct and go get the correct stuff. I hope When i disconnect the trunk from the A/C unit that it isnt that hard to go from the 20"x9" to a a bigger 24"x10" or whatever combo makes it 240 square inches. So it doesnt matter how tall or long it is, as long as it comes out to the same Square inches per section?
What are the common sizes available to people at local hardware stores?
hmmm do you need any special tools to make your own? I recall Home depot selling like sheets of the metal, wasnt quiet sure how to turn that into a trunk.
Is the tool similar to this http://www.homedepot.com/webapp/wc s/stores/servlet/ProductDisplay?storeId=10051&productId=100648037&langId=-1&catalogId=10053&ci_sku=100648037&ci_src=14110944&cm_mmc=shopping-_-googlebase-_-D27X-_-100648037&locStoreNum=4163&marketID=34
Along with like umm S Cleats or something like that?
LOL well I dont think ill be picking one of those up anytime soon LOL
Ok, last question, When you say 10" high x 24" wide, how long does that particular trunk need to be or does the length not matter cause a 10"x24" by 5 foot piece will have a higher square inch than a 3foot etc
ok, that makes sense. Ill just pretty much follow the design. Its pretty much like how it is now except I will be making the trunk a bit bigger. Thanks again, ill leave you be now heh.. plus i have to clean the mess before my wife comes home :P
Ill let you know how it turns out.