- My Forums
- Tiger Rant
- LSU Recruiting
- SEC Rant
- Saints Talk
- Pelicans Talk
- More Sports Board
- Fantasy Sports
- Golf Board
- Soccer Board
- O-T Lounge
- Tech Board
- Home/Garden Board
- Outdoor Board
- Health/Fitness Board
- Movie/TV Board
- Book Board
- Music Board
- Political Talk
- Money Talk
- Fark Board
- Gaming Board
- Travel Board
- Food/Drink Board
- Ticket Exchange
- TD Help Board
Customize My Forums- View All Forums
- Show Left Links
- Topic Sort Options
- Trending Topics
- Recent Topics
- Active Topics
Started By
Message
A/C Ducting Design - Jumper Ducts for Hot Bedrooms with a Hallway Return
Posted on 5/23/19 at 7:47 pm
Posted on 5/23/19 at 7:47 pm
ETA- Thread Title Update.
Growing up, my dad built our house in the late 70's and every room had its own return. Upstairs, it would stay cool if you kept all the bedroom doors closed.
Every house I've lived in since, every single one, had a centrally located return.
The house I live in now, has a centrally located return upstairs. In the hallway. Where the stairs are.
So, all the cool air that comes out of the vents, when bedroom doors are open, just cascades down the stairs. But if you close the doors, the rooms stay slightly cooler, but not much because of air pressure because there's no return in the rooms.
So, engineers of Tigerdroppings...
My attic is wide open. You could put in a half-court up there.
Would it be a good idea to cut in returns in each upstairs bedroom and close off the central return upstairs?
Growing up, my dad built our house in the late 70's and every room had its own return. Upstairs, it would stay cool if you kept all the bedroom doors closed.
Every house I've lived in since, every single one, had a centrally located return.
The house I live in now, has a centrally located return upstairs. In the hallway. Where the stairs are.
So, all the cool air that comes out of the vents, when bedroom doors are open, just cascades down the stairs. But if you close the doors, the rooms stay slightly cooler, but not much because of air pressure because there's no return in the rooms.
So, engineers of Tigerdroppings...
My attic is wide open. You could put in a half-court up there.
Would it be a good idea to cut in returns in each upstairs bedroom and close off the central return upstairs?
This post was edited on 5/24/19 at 11:22 am
7
Posted on 5/23/19 at 8:26 pm to deeprig9
Look forward to seeing the replies/suggestions you get with your question.
I too have a single return vent in a hallway. My understanding one should have 400 cfm of return vent area per ton of AC. Each sq in of of return vent should accommodate 2 cfm of return air flow. I have a single 24 x 24 return vent, so that should accommodate 1152 cfm of return air flow (24 x 24 x 2). But I have a 4 ton HVAC so I should have 1,600 cfm of return vent area, so it looks like I need about an additional 450 cfm of return vent area.
I plan to correct this, and like you I have have an abundance of attic space. I’ll seek advice of HVAC professionals on how best to accomplish this, but I’m thinking a second return vent in another hallway, but maybe a few additional smaller return vents in bedrooms would be the way to go.
I too have a single return vent in a hallway. My understanding one should have 400 cfm of return vent area per ton of AC. Each sq in of of return vent should accommodate 2 cfm of return air flow. I have a single 24 x 24 return vent, so that should accommodate 1152 cfm of return air flow (24 x 24 x 2). But I have a 4 ton HVAC so I should have 1,600 cfm of return vent area, so it looks like I need about an additional 450 cfm of return vent area.
I plan to correct this, and like you I have have an abundance of attic space. I’ll seek advice of HVAC professionals on how best to accomplish this, but I’m thinking a second return vent in another hallway, but maybe a few additional smaller return vents in bedrooms would be the way to go.
Posted on 5/23/19 at 8:28 pm to deeprig9
Your dad must have hated changing all those filters.
Posted on 5/23/19 at 8:33 pm to OysterPoBoy
quote:
Your dad must have hated changing all those filters.
One filter yo. Right before going into the indoor unit thing in the attic.
Same as my house now. The filter isn't in the return vent, you have to go into the attic and slide it out at the unit.
Only difference in my plan is instead of one big duct going to one big return, is multiple smaller ducts going to multiple returns spread out.
But you probably knew that already and you were just trying to be funny. Afterall, you know alot about HVAC and the actual physics and mechanics and whatnot. Everyone around here knows you are a real expert. So no disrespect.
Posted on 5/23/19 at 8:40 pm to deeprig9
Oh, of course. I definitely knew that.
Posted on 5/23/19 at 8:40 pm to deeprig9
If your air handler is in the attic, lucky you. Go for it. You can't have too much return.
Posted on 5/23/19 at 8:51 pm to CrawDude
144 sq in per ton is what you need. Your good.
Posted on 5/23/19 at 8:54 pm to deeprig9
You could leave the central return and add smaller returns in each room. Or even just add crossover ducts from room to central location
Posted on 5/23/19 at 9:29 pm to jmkidder
quote:
144 sq in per ton is what you need. Your good.
Thanks. I’ve seen 144 sq in recommendation and a HVAC rep I asked last year when getting HVAC replacement quotes told me same. But the most frequent recommendation I see now days is 200 sq in per ton. Anyway, I’ll get this sorted out. If as notsince99 says excess return air is not an issue the time to handle this when I replace the HVAC.
Posted on 5/23/19 at 10:08 pm to deeprig9
The idea in the past was just to heat and cool individual rooms, not the hallways.
Maybe I recall incorrectly, but older homes didn't have a air register in any hallway.
Maybe I recall incorrectly, but older homes didn't have a air register in any hallway.
Posted on 5/24/19 at 10:59 am to deeprig9
Eureka!
Jumper Ducts!
I can probably even do this myself!
Jumper Ducts for Bedrooms
Instead of reconfiguring the whole upstairs return layout, I just put jumper ducts from inside the bedroom to the hallway where the main return is.
Jumper Ducts!
I can probably even do this myself!
Jumper Ducts for Bedrooms
Instead of reconfiguring the whole upstairs return layout, I just put jumper ducts from inside the bedroom to the hallway where the main return is.
Posted on 5/24/19 at 11:42 am to deeprig9
An alternate to jumper ducts is having a 2" opening at the bottom of the door between it and the floor. I think you can also get doors with grills.
Posted on 5/24/19 at 11:56 am to notsince98
quote:
An alternate to jumper ducts is having a 2" opening at the bottom of the door between it and the floor. I think you can also get doors with grills.
Problems there-
1: Ugly
2: Bottom of door means the cooler air gets out, opposite of what I'm trying to accomplish. Could put at top of door. But still ugly.
3: Bedroom privacy and sound
4: Cutting drywall easier than cutting door
But at work we do use louvred doors in IT rooms for ventilation and it does work very well. Your idea isn't a bad one, just not right for my situation.
I'm putting my part numbers together now to share with the engineers of the HG board.
There's one thing I might have to get custom from an HVAC guy.
Stand by.
Posted on 5/24/19 at 12:05 pm to deeprig9
One of these in each of the three bedroom ceilings-
LINK
SPEEDI- BOOT
6 in. W x 10 in. L to 6 in. Diameter 90-Degree Register Vent Boot with Adjustable Hangers
6 inch flexible ducting to a new register, which will need a custom 6x6x6x12 Three Way junction. That's what I'm having a hard time finding. I can find other dims, but not 6x6x6x12.
One of these in the hallway to dump the warm return air. About 10 feet from the actual return. I would do it closer but the attic door is in the way.
LINK
SPEEDI- BOOT
14 in. W x 14 in. L to 12 in. Dia Square-to-Round Register Vent Boot with Adjustable Hangers
Where can I get a 6x6x6x12 junction?
LINK
SPEEDI- BOOT
6 in. W x 10 in. L to 6 in. Diameter 90-Degree Register Vent Boot with Adjustable Hangers
6 inch flexible ducting to a new register, which will need a custom 6x6x6x12 Three Way junction. That's what I'm having a hard time finding. I can find other dims, but not 6x6x6x12.
One of these in the hallway to dump the warm return air. About 10 feet from the actual return. I would do it closer but the attic door is in the way.
LINK
SPEEDI- BOOT
14 in. W x 14 in. L to 12 in. Dia Square-to-Round Register Vent Boot with Adjustable Hangers
Where can I get a 6x6x6x12 junction?
This post was edited on 5/24/19 at 12:06 pm
Posted on 5/24/19 at 1:32 pm to deeprig9
quote:
Where can I get a 6x6x6x12 junction?
That is basically a plenum if I understand what you are trying to accomplish correctly. Those are essentially fabricated on site to fit the needs of the job.
Posted on 5/24/19 at 2:33 pm to MikeBRLA
I could just take a 6 inch hole saw into the return duct three times, Bring the 6 inch flex duct to it, and jb weld the 6 inch "receivers" on an take the flex straight in. No new ceiling holes or specialty fittings. I just don't want a future inspector to get pissed when I try to sell.
Posted on 5/24/19 at 4:00 pm to deeprig9
Are you trying to say that the return air is too warm because its all being pulled from the the warm hallway and not the cooler bedrooms?
Otherwise I don't see how moving air from the bedrooms around or grabbing air from the bedrooms helps.
Are these large bedrooms? More often then not I see bedrooms getting very cold compared to the living space and hallways not having as many vents as the bedrooms.
For instance, I have the opposite problem in a 1980s home where the 2 bedrooms upstairs get frigid and we often time completely shut the vents.
Otherwise I don't see how moving air from the bedrooms around or grabbing air from the bedrooms helps.
Are these large bedrooms? More often then not I see bedrooms getting very cold compared to the living space and hallways not having as many vents as the bedrooms.
For instance, I have the opposite problem in a 1980s home where the 2 bedrooms upstairs get frigid and we often time completely shut the vents.
This post was edited on 5/24/19 at 4:02 pm
Posted on 5/24/19 at 5:10 pm to deeprig9
I have one of those for our master bedroom, but no others. Initially, I thought it was a air supply register on both sides til I looked in the attic to see what was going on
Posted on 5/24/19 at 6:00 pm to baldona
quote:
Otherwise I don't see how moving air from the bedrooms around or grabbing air from the bedrooms helps.
You have to think of supply and return. Anywhere there isn't enough return, the static pressure for that supply is higher than elsewhere so the flow goes elsewhere down the easiest path.
In this posters situation, when bedroom doors are closed, the pressure on the bedroom supplies is enough more air goes out the downstairs supplies. This makes the bedroom warmer.
Adding better returns to the bedrooms boosts the supplies when the doors are closed and provides more cooling when the doors are closed.
Posted on 5/24/19 at 6:06 pm to notsince98
Not exactly. Separate air handler downstairs. The upstairs air that goes downstairs is the invisible waterfall down the staircase, if the BR doors are open. If BR doors are closed, positive pressure prevents flow of cool air to the rooms. Putting return duct in each bedroom solves this, if doors are closed.
Page 1 of 2
Popular
Back to top
Follow TigerDroppings for LSU Football News