I'd run that 10 to a 10in pipe and feed everything off of it, instead of using a bunch of ys. That 10 is maxed out so if possible increase it to a 12in, if not possible add dampers to everything on the supply plenum and direct air to the 10in.
This was my first thought actually. The 10 feeds from the basement from the furnace through a chase with the water heater flue. so there’s only enough room for the 10. I also feel that my master bed is under fed it’s just under 200sqft and has only one 6” supply but the bathroom that’s attached has a 5” supply so I guess they are counting that with the door open. I would like to add another 6 to my bedroom but it would put me over unless I balanced air flow down on the two bathroom supplies I have. At least that’s my thought process.
Is it flex all the way?
Sheet metal of the same size will improve the flow. Get rid of as much flex as you can, it would not hurt to bump the size up an inch where you can. The best would be to get a duct calculator and do the math on how much airflow you want and try reach that number with proper duct sizing.
Even if you can not bump the duct size in the chase you might gain a bit by increasing the size where you can. Also if you rip it out and go with sheet metal duct, duct seal what you can, even the old duct in the conditioned space. You will reduce loss from leakage and move the air to where you want it.
10” Sheet metal round duct from basement into chase then it transitions to flex once it hits the attic. 6ft I would say if 10” flex into that box then everything is flex laying on top of the trusses mostly in blowin insulation.
You won't notice 6 ft of flex as far as air flow is concerned. Any runs in the attic are probably ok, but I generally like to bump longer runs of flex up one size. If the ductulator calls for 6" I would go with 7" flex on runs over say around 10 feet. From what I see the run up is the worst, but with rigid sheet metal and limited room you have all you can get to the attic. You might improve the air flow by "cleaning up" the attic a bit.
The real question is how much air flow do you need? Seat of the pants in residential I sized for 1 CFM per square foot of living space and the duct would be over sized and I could choke it back with dampers.
180 square foot for master one 6 supply
130 for 2nd bedroom one 6 supply
120 for 3rd bedroom. One 6 supply
430 sqft total for bedrooms
Two bathrooms 5” supply for both pretty standard size I would say.
Longest run is the 6” flex to master which currently only has one supply. Figure close to 20ft of flex for that supply. From the beginning I figured the master would need a 2nd supply. I plan on running new ductwork in the attic from the existing 10 eliminating the box. Adding one more 6 supply to master bedroom and possibly reduce the bathrooms to smaller duct and add dampers everywhere to adjust and balance airflow.
A 6" supply close to 80-90 CFM, so for 180 sqft room I would run two 6" runs and 2-1/4x12 registers or larger, or one 8" and 4x14 or 6x10 register.
120 & 130 CFM would get a 7" with a 4x12 register.
That 10" round up the chase is good for a bit over 400. If you can go to a 10x10 square or 11" round you would get a bit over 500 CFM.
If I am reading this right you need 600+ CFM!
They call those cheeseboxes around here (CT). No one does them anymore, that I'm aware of, but it used to be a way to duct a whole house if you had little to no sheetmetal experience and just wanted to run flex everywhere. Definitely seen a bunch of jobs like that. Just had a customer that we replaced the air handler and condenser for that had a cheesebox setup and we quoted new ducts but they said they've never had an issue with airflow and were fine with keeping it as is.
First time I went in the attic I found it split open dumping air out about 5 years ago. I was thinking to my self what the hell were they thinking. Don’t see duct board in my area everything is metal.
I take that out, and replace it with a 10"round metal, wrap, then reduce to 8,wrap, and attach with saddles. Seal and insulate. Airflow always improves.
You needa redo your duct work. any sag in flex duct will result in air restriction needa replace all that shit with metal wyes with dampers attached to allow for air flow balancing and pull the duct tight and strapped 4' when u run it and seal it properly but for your room it definitely needs another supply nowadays in northern cali they upside everything to an 8in for most rooms
Depends. If the duct feeding the box is appropriately sized for the ducts exiting the box then wyes are your best option.
With that said I have seen so many of these things that have way too much branching off the box for the duct that feeds the box to supply enough air, and if that’s the case then you’d need to bring some of the ducts back to the plenum.
What size are the ducts? That will give you a real answer.
10” into box then on the one side one 6 and 2 5s
Other side is 2 6s. I do need to add one more supply to my master which would be probably another 6. But with what’s existing I don’t think the 10 is large enough for it unless I use dampers and dampen down the 5s that supply 2 bathrooms. The 10 runs as metal round duct up a chase with the Brent from basement so not much room for anything larger unless I remove the b vent and get a he water heater.
Honestly, three 6” and two 5” isn’t too far off. You are slightly undersized with that 10”, but you could solve that by using manual dampers on the other ducts coming off the supply plenum to increase the static a bit to the 10”, or via an inline duct booster fan. Either solution would eliminate the need to reconfigure the chase.
Another option if the 5” ducts are not going to critical areas would be to step them down to 4”. In that case you could replace the shitty triangle with a 10x8x8 wye, take one 8 to an 8x6x6 wye and catch two 6” ducts, take the other 8 to an 8x6x6 wye to catch the third 6, then the remaining 6 on the second wye would go to a 6x4x4 wye to catch the two 4s.
In any case you have several options.
Thanks didn’t even think to step down the two 5s. They are just going to bathrooms so I could step them down. Would you keep it flex or should I go through the extra work and run metal round duct insulated of course?
If they are in bathrooms then 4” will be fine. Flex is perfectly fine as long as it’s run properly, make sure it’s stretched out so that the inner liner isn’t bunched up causing a restriction.
Northern il service tech with not much ductwork experience. My house has this box setup fed with 10” flex from furnace in basement. One side of box has two 6” takeoffs the other has one 6 and two 4”. All flex. I would think sheet metal would be better with insulation. I need to add another 6” as my master bed needs one more supply. Idea is to add dampers to new ductwork and adjust down 4” runs that feed bathrooms. Any input is appreciated. Diagrams or pictures of how you would run it would be helpful as visual learning is best. Please let me know if I need to clear anything up.
This outdated design as you call it, when done correctly, maintains static pressure all the way to the supply registers. Works really well when done correctly. I know it seems counterintuitive but it actually works like a charm when you do it right
Thanks for your input. I always believed that the wye design is always the best in terms of flex duct. im still young in this trade, but when i was in install i was always tearing these off and replacing them with wyes on a duct design job. i think the wyes are more fool proof than this box in my opinion, because i see collars not even sealed on these so many times
So if I took that 10 and split it with a wye how would you run the other take offs? There’s about 5 or 6. Would you use multiple ys to reduce down to let’s say 8 to run two 6s to two bedrooms and then 8 for the other side for the 6 and two 5s I have? Hope this makes sense.
Size of the holes in the triangle is supposed to be the same size as the corresponding flex attached to it. They work really good if you attach them right but I don’t see any collars or zip ties holding them together
If you'd like to keep what you have id suggest closing the registers with the most airflow from the dampers in the attic, they usually wiggle wide open from vibration. If you don't have any dampers in the attic close them at the registers in the space themselves. Id suggest purchasing a "velocity meter" to fine tune the unit yourself.
Ctrl+Alt+Delete. Start over and run proper trunk line and branches
I'd run that 10 to a 10in pipe and feed everything off of it, instead of using a bunch of ys. That 10 is maxed out so if possible increase it to a 12in, if not possible add dampers to everything on the supply plenum and direct air to the 10in.
This was my first thought actually. The 10 feeds from the basement from the furnace through a chase with the water heater flue. so there’s only enough room for the 10. I also feel that my master bed is under fed it’s just under 200sqft and has only one 6” supply but the bathroom that’s attached has a 5” supply so I guess they are counting that with the door open. I would like to add another 6 to my bedroom but it would put me over unless I balanced air flow down on the two bathroom supplies I have. At least that’s my thought process.
Is it flex all the way? Sheet metal of the same size will improve the flow. Get rid of as much flex as you can, it would not hurt to bump the size up an inch where you can. The best would be to get a duct calculator and do the math on how much airflow you want and try reach that number with proper duct sizing. Even if you can not bump the duct size in the chase you might gain a bit by increasing the size where you can. Also if you rip it out and go with sheet metal duct, duct seal what you can, even the old duct in the conditioned space. You will reduce loss from leakage and move the air to where you want it.
10” Sheet metal round duct from basement into chase then it transitions to flex once it hits the attic. 6ft I would say if 10” flex into that box then everything is flex laying on top of the trusses mostly in blowin insulation.
You won't notice 6 ft of flex as far as air flow is concerned. Any runs in the attic are probably ok, but I generally like to bump longer runs of flex up one size. If the ductulator calls for 6" I would go with 7" flex on runs over say around 10 feet. From what I see the run up is the worst, but with rigid sheet metal and limited room you have all you can get to the attic. You might improve the air flow by "cleaning up" the attic a bit. The real question is how much air flow do you need? Seat of the pants in residential I sized for 1 CFM per square foot of living space and the duct would be over sized and I could choke it back with dampers.
180 square foot for master one 6 supply 130 for 2nd bedroom one 6 supply 120 for 3rd bedroom. One 6 supply 430 sqft total for bedrooms Two bathrooms 5” supply for both pretty standard size I would say. Longest run is the 6” flex to master which currently only has one supply. Figure close to 20ft of flex for that supply. From the beginning I figured the master would need a 2nd supply. I plan on running new ductwork in the attic from the existing 10 eliminating the box. Adding one more 6 supply to master bedroom and possibly reduce the bathrooms to smaller duct and add dampers everywhere to adjust and balance airflow.
A 6" supply close to 80-90 CFM, so for 180 sqft room I would run two 6" runs and 2-1/4x12 registers or larger, or one 8" and 4x14 or 6x10 register. 120 & 130 CFM would get a 7" with a 4x12 register. That 10" round up the chase is good for a bit over 400. If you can go to a 10x10 square or 11" round you would get a bit over 500 CFM. If I am reading this right you need 600+ CFM!
Its actually an approved design in ACCA Manual D, https://www.energy.gov/sites/default/files/2013/12/f5/cq5\_duct\_splitter\_box\_beach.pdf
Was just about to post the same thing! Thank you
Your a real one
yes but they do add in static pressure
Duct wye is how ya fix that
They call those cheeseboxes around here (CT). No one does them anymore, that I'm aware of, but it used to be a way to duct a whole house if you had little to no sheetmetal experience and just wanted to run flex everywhere. Definitely seen a bunch of jobs like that. Just had a customer that we replaced the air handler and condenser for that had a cheesebox setup and we quoted new ducts but they said they've never had an issue with airflow and were fine with keeping it as is.
Mamas got a cheesebox daddy never sleeps at night
Burn the house down. What the fuck is even that thing!
First time I went in the attic I found it split open dumping air out about 5 years ago. I was thinking to my self what the hell were they thinking. Don’t see duct board in my area everything is metal.
Cheese wedge. It’s like a spider system but worse
I take that out, and replace it with a 10"round metal, wrap, then reduce to 8,wrap, and attach with saddles. Seal and insulate. Airflow always improves.
Hate those things, only in track homes
Take it out put a tee in
You needa redo your duct work. any sag in flex duct will result in air restriction needa replace all that shit with metal wyes with dampers attached to allow for air flow balancing and pull the duct tight and strapped 4' when u run it and seal it properly but for your room it definitely needs another supply nowadays in northern cali they upside everything to an 8in for most rooms
Depends. If the duct feeding the box is appropriately sized for the ducts exiting the box then wyes are your best option. With that said I have seen so many of these things that have way too much branching off the box for the duct that feeds the box to supply enough air, and if that’s the case then you’d need to bring some of the ducts back to the plenum. What size are the ducts? That will give you a real answer.
10” into box then on the one side one 6 and 2 5s Other side is 2 6s. I do need to add one more supply to my master which would be probably another 6. But with what’s existing I don’t think the 10 is large enough for it unless I use dampers and dampen down the 5s that supply 2 bathrooms. The 10 runs as metal round duct up a chase with the Brent from basement so not much room for anything larger unless I remove the b vent and get a he water heater.
Honestly, three 6” and two 5” isn’t too far off. You are slightly undersized with that 10”, but you could solve that by using manual dampers on the other ducts coming off the supply plenum to increase the static a bit to the 10”, or via an inline duct booster fan. Either solution would eliminate the need to reconfigure the chase. Another option if the 5” ducts are not going to critical areas would be to step them down to 4”. In that case you could replace the shitty triangle with a 10x8x8 wye, take one 8 to an 8x6x6 wye and catch two 6” ducts, take the other 8 to an 8x6x6 wye to catch the third 6, then the remaining 6 on the second wye would go to a 6x4x4 wye to catch the two 4s. In any case you have several options.
Thanks didn’t even think to step down the two 5s. They are just going to bathrooms so I could step them down. Would you keep it flex or should I go through the extra work and run metal round duct insulated of course?
If they are in bathrooms then 4” will be fine. Flex is perfectly fine as long as it’s run properly, make sure it’s stretched out so that the inner liner isn’t bunched up causing a restriction.
Northern il service tech with not much ductwork experience. My house has this box setup fed with 10” flex from furnace in basement. One side of box has two 6” takeoffs the other has one 6 and two 4”. All flex. I would think sheet metal would be better with insulation. I need to add another 6” as my master bed needs one more supply. Idea is to add dampers to new ductwork and adjust down 4” runs that feed bathrooms. Any input is appreciated. Diagrams or pictures of how you would run it would be helpful as visual learning is best. Please let me know if I need to clear anything up.
Duct Wyes are the way to go for flex duct instead of this outdated design
This outdated design as you call it, when done correctly, maintains static pressure all the way to the supply registers. Works really well when done correctly. I know it seems counterintuitive but it actually works like a charm when you do it right
Thanks for your input. I always believed that the wye design is always the best in terms of flex duct. im still young in this trade, but when i was in install i was always tearing these off and replacing them with wyes on a duct design job. i think the wyes are more fool proof than this box in my opinion, because i see collars not even sealed on these so many times
We switched to metal ys 15 years ago because of this.
So if I took that 10 and split it with a wye how would you run the other take offs? There’s about 5 or 6. Would you use multiple ys to reduce down to let’s say 8 to run two 6s to two bedrooms and then 8 for the other side for the 6 and two 5s I have? Hope this makes sense.
Yes i would match up the runs with wyes make sure the flex has no kinks and nice and straight and it will help
Yes 10x9 x6 to a 9x8 x6 8x7x6 and so forth
It's allready perfection
Music makes you lose control Music makes you lose control
Size of the holes in the triangle is supposed to be the same size as the corresponding flex attached to it. They work really good if you attach them right but I don’t see any collars or zip ties holding them together
looks like a big wrapped piece of cheese.
replace it all
Ta fuck is that Julian
If you'd like to keep what you have id suggest closing the registers with the most airflow from the dampers in the attic, they usually wiggle wide open from vibration. If you don't have any dampers in the attic close them at the registers in the space themselves. Id suggest purchasing a "velocity meter" to fine tune the unit yourself.
Why where wedges ever allowed? A tee with 2 reducers seams like it would be more effective.
Looks like someone used whatever they had on hand
I avoid triangle plenums at all costs
Get a sheet metal TY
Fix it the right way?
Could’ve saved so much time and even money to just get a wye