So true, an HVAC source I know of and having about 35 years of experience told me that the returns should be about 2X or twice the volume of the total supply ducts. He said more than 50% of HVAC installs that he has seen do not follow that rule/idea. I personally know of huge tract developments in Southern California that have most of their returns located right below or to the side of the HVAC cabinet and my guess is to save money on materials. How/why local codes allow this in a state or county that is so concerned about energy consumption and efficiency no one really understands. But, the real negative is THE NOISE that is made with those inferior ideas. Its ridiculous to say the least. Efficiency must be way off in addition to the noise. Plus, the HVAC filter location is usually hard to get to vs. being located at a return register or registers. My personal HVAC guy told me 30 years ago that the more there are returns, the better and that all supply registers should be open vs. closed in rooms not being used as that defeats air flow at the plenum. He also explained the difference in the cheap stamped metal registers and those that are "rolled" metal that improve air flow and direction of flow. I truly learned much back then and found over the years of observing how the many homes I've been to where HVAC quality is way below many standards that applied back when they were installed let alone todays standards. Even the locations of the condensers and air handlers are so far off you simply had to wonder what was the goal when they were installed. Very sad that we see licensed HVAC folk doing this kind of work and local city codes and/or their inspectors allowing it to occur. My observations tell me that any two story home should require two (2) HVAC systems, one for up and one for down, large returns with the filters located inside them and ducting designs without excess duct lengths or kinks in them and properly hung/routed and then proper locations for the equipment, inside and outside. It's sad that the huge tract developments get overlooked as they do since they also carry a large portion of the waste in efficiency etc. than a smaller development does.
I've got about 3 foot x 4 foot return made by the walls in my house. No metal panning- no nothing. Returns my ac to the basement air handler. It's odd. I posted about it and many in the business said its routinely done. Huh. Love your videos. You're a wealth of construction knowledge. Thanks!
I feel your pain! just saw a This Old House (or might have been an “Ask” TOH) episode where they quoted that something like 80% of houses with central air were judged by their owners as having uncomfortable heating/cooling. My experience is that in the HVAC (and other) trades they “do it like they do it” and absolutely will not follow design, sizing, sealing, etc calculated by an engineer or specified by an architect unless it happens to coincide with what they are comfortable with. I just had a large damaged whole window replaced and installer refused to integrate it with the existing house air/water barrier or even use flashing or caulk it “because we don’t do it that way around here”. Huh?
Those stud returns are clever however, myself I would prefer the sheet metal to be 100% enclosed so that the return air can be filtered at the return register vs. at or near the air handler. If not, all of the return ducting will eventually collect dirt over the years as it has to be filtered near the air handler since there would be some air leakage from the looks of it, this side of the camera.
I live in a 1954 built house and they are using the same return air ducts method between basement rafters. They use plain old galvanized sheet metal. When the previous owners remodeled, they did not install air returns in two of the added on rooms. So there is not enough air turn vents for each air vent. In the basement the return vent on the heating/ac unit sucks in so much air that its pulling air from upstairs under basement door crack.
All my returns are just directly in the stud cavity no pan. 1960s house. They're all near the floor too, so the summer gets way too hot in some rooms. I think I'll just bust a hole up higher and add another vent grill. Then cover the lower one. Does that make sense to help move hot air out of a room?
Will the pans confuse a studfinder used by a homeowner who wants to hammer picture frame nails into wall studs? And what will happen if the homeowner installs anchor bolts into drywall without knowing the ductwork is lurking behind the drywall?
Thermopan is just fancy cardboard with a slightly higher burning point. And puncturing it is one of the main problems of using a wall cavity as a return, now you are pulling unfiltered air into the system
However panning is not approved by the NFPA and several codes do not allow it. Bare wood is not allowable by fire code "Materials exposed within ducts or plenums shall be noncombustible or shall have a flame spread index not to exceed 25 and a smoke-developed index not to exceed 50, where tested as a composite product in accordance with ASTM E84 or UL 723." An hvac contractor could be held liable if a fire is found to have spread through a panned bay.
IECC 2021 is pressured by EPA and has tightness testing conditions. You can use duct board, but will never pass duct tightness test your supposed to be doing. Your jurisdiction is simply 20 years behind.
i mean...we have clearance issues. i don't see why i can't use the space to supply air? i'm using the floor system and fully insulating the joist cavity. Top, sides, and bottom with 1/2 foil polystyrene. lexel all the crack, and make sure no "air" touches framing members??
If you are moving from one floor to the next, are you allowed to cut through the top/bottom plates of the framing? For instance, for second-story return air, can you cut away the horizontal framing members from the second story all the way down into the basement?
I know in my 1979 house that's exactly what they did. I think there are special brackets that are supposed to be used where the plates are cut to prevent separation or twisting but mine had nothing and it's been fine.
Joist panning for return air ducts goes against code in certain areas, for a number of reasons. Unless it is properly sealed, which usually they are not, it is creating a negative pressure and sucking air in from the wall cavities and subsequently the sill plates. Therefore, you are sucking in hot, humid air in the summer and cold air in the winter. Second, panned returns are considered a fire hazard due to how they can increase the rate at which fire spreads. Lastly, they can cause the backdrafting of harmful air from appliances. It should be illegal everywhere to joist pan an HVAC return. In my opinion it's just an excuse for cheap, lazy work. The ideal scenario would be to duct the return.
it's done all the time in retrofit applicatons - very stupid to remove the plaster/drywall just to pan it off. panned off returns are leaky as hell even with panning. @@publicmail2
LMAO @ the incredibly stupid reason to not use a joist cavity as a supply duct...you've got to be absolutely kidding me...your heater malfunctioning and super heating the framing? Are we fucking serious right now? In what twisted dimension of reality is this a legitimate concern? Even if it were that wouldn't apply to an AC only system that has no built in furnace...would it? So many quesions about that...with the number one being how did we as a society become stupid enough to accept such garbage reasoning for not being allowed to do something so obviously beneficial. I will do it anyway on my house...
So true, an HVAC source I know of and having about 35 years of experience told me that the returns should be about 2X or twice the volume of the total supply ducts. He said more than 50% of HVAC installs that he has seen do not follow that rule/idea. I personally know of huge tract developments in Southern California that have most of their returns located right below or to the side of the HVAC cabinet and my guess is to save money on materials. How/why local codes allow this in a state or county that is so concerned about energy consumption and efficiency no one really understands. But, the real negative is THE NOISE that is made with those inferior ideas. Its ridiculous to say the least. Efficiency must be way off in addition to the noise. Plus, the HVAC filter location is usually hard to get to vs. being located at a return register or registers. My personal HVAC guy told me 30 years ago that the more there are returns, the better and that all supply registers should be open vs. closed in rooms not being used as that defeats air flow at the plenum. He also explained the difference in the cheap stamped metal registers and those that are "rolled" metal that improve air flow and direction of flow. I truly learned much back then and found over the years of observing how the many homes I've been to where HVAC quality is way below many standards that applied back when they were installed let alone todays standards. Even the locations of the condensers and air handlers are so far off you simply had to wonder what was the goal when they were installed. Very sad that we see licensed HVAC folk doing this kind of work and local city codes and/or their inspectors allowing it to occur. My observations tell me that any two story home should require two (2) HVAC systems, one for up and one for down, large returns with the filters located inside them and ducting designs without excess duct lengths or kinks in them and properly hung/routed and then proper locations for the equipment, inside and outside. It's sad that the huge tract developments get overlooked as they do since they also carry a large portion of the waste in efficiency etc. than a smaller development does.
My house built 30 years ago has stud wall air return. It has been quiet and seems to work fine.
I've got about 3 foot x 4 foot return made by the walls in my house. No metal panning- no nothing. Returns my ac to the basement air handler. It's odd. I posted about it and many in the business said its routinely done. Huh.
Love your videos. You're a wealth of construction knowledge. Thanks!
I feel your pain! just saw a This Old House (or might have been an “Ask” TOH) episode where they quoted that something like 80% of houses with central air were judged by their owners as having uncomfortable heating/cooling. My experience is that in the HVAC (and other) trades they “do it like they do it” and absolutely will not follow design, sizing, sealing, etc calculated by an engineer or specified by an architect unless it happens to coincide with what they are comfortable with. I just had a large damaged whole window replaced and installer refused to integrate it with the existing house air/water barrier or even use flashing or caulk it “because we don’t do it that way around here”. Huh?
@@dac7046 and unfortunately many times you don’t know the right things to ask until it’s too late or the company has already done the job.
@@dac7046very sad that you got work done like that !!
Never heard of that before. Thanks
Those stud returns are clever however, myself I would prefer the sheet metal to be 100% enclosed so that the return air can be filtered at the return register vs. at or near the air handler. If not, all of the return ducting will eventually collect dirt over the years as it has to be filtered near the air handler since there would be some air leakage from the looks of it, this side of the camera.
Great solution! Just what I needed
I live in a 1954 built house and they are using the same return air ducts method between basement rafters. They use plain old galvanized sheet metal. When the previous owners remodeled, they did not install air returns in two of the added on rooms. So there is not enough air turn vents for each air vent. In the basement the return vent on the heating/ac unit sucks in so much air that its pulling air from upstairs under basement door crack.
enjoy your show as always.
Doesn't mention condensation and moisture leading to mold issues. See Matt Risinger and Corbett Lunsford on that.
Printed side out, with connectors and aluminum flashing tape. Why do they charge more for 16” widths than 24”?
All my returns are just directly in the stud cavity no pan. 1960s house. They're all near the floor too, so the summer gets way too hot in some rooms. I think I'll just bust a hole up higher and add another vent grill. Then cover the lower one. Does that make sense to help move hot air out of a room?
Will the pans confuse a studfinder used by a homeowner who wants to hammer picture frame nails into wall studs? And what will happen if the homeowner installs anchor bolts into drywall without knowing the ductwork is lurking behind the drywall?
Thermopan is just fancy cardboard with a slightly higher burning point. And puncturing it is one of the main problems of using a wall cavity as a return, now you are pulling unfiltered air into the system
@@turnedearthdesign8678 : The location of the air filter would determine whether air pulled in through a puncture would be filtered.
The vent is too close to the wall. If you put crown Moulding it will need to be notched.
What about existing cavities?
However panning is not approved by the NFPA and several codes do not allow it. Bare wood is not allowable by fire code "Materials exposed within ducts or plenums shall be noncombustible or shall have a flame spread index not to exceed 25 and a smoke-developed index not to exceed 50, where tested as a composite product in accordance with ASTM E84 or UL 723." An hvac contractor could be held liable if a fire is found to have spread through a panned bay.
IECC 2021 is pressured by EPA and has tightness testing conditions. You can use duct board, but will never pass duct tightness test your supposed to be doing. Your jurisdiction is simply 20 years behind.
i mean...we have clearance issues. i don't see why i can't use the space to supply air? i'm using the floor system and fully insulating the joist cavity. Top, sides, and bottom with 1/2 foil polystyrene. lexel all the crack, and make sure no "air" touches framing members??
Can you cut panning ie 22 inch down to 20
Absolutely!
what happens if someone puts a nail through the wall
Nothing
If you are moving from one floor to the next, are you allowed to cut through the top/bottom plates of the framing? For instance, for second-story return air, can you cut away the horizontal framing members from the second story all the way down into the basement?
I know in my 1979 house that's exactly what they did. I think there are special brackets that are supposed to be used where the plates are cut to prevent separation or twisting but mine had nothing and it's been fine.
You don't put forced air through a joist cavity because it fills up with dust and is impossible to clean properly
Anything would beat what was done under my house....you can't get to the other side of my foundation...
Joist panning for return air ducts goes against code in certain areas, for a number of reasons. Unless it is properly sealed, which usually they are not, it is creating a negative pressure and sucking air in from the wall cavities and subsequently the sill plates. Therefore, you are sucking in hot, humid air in the summer and cold air in the winter. Second, panned returns are considered a fire hazard due to how they can increase the rate at which fire spreads. Lastly, they can cause the backdrafting of harmful air from appliances.
It should be illegal everywhere to joist pan an HVAC return. In my opinion it's just an excuse for cheap, lazy work. The ideal scenario would be to duct the return.
the drywall or plaster can also work as pan.
No
Sure why not. return air.
it's done all the time in retrofit applicatons - very stupid to remove the plaster/drywall just to pan it off. panned off returns are leaky as hell even with panning. @@publicmail2
Junk. Stop using any tape in the airflow stream.Tape and plasma cutter labels eventually dry out and make a fluttering noise. Use mastic.
Wtf???
LMAO @ the incredibly stupid reason to not use a joist cavity as a supply duct...you've got to be absolutely kidding me...your heater malfunctioning and super heating the framing? Are we fucking serious right now? In what twisted dimension of reality is this a legitimate concern? Even if it were that wouldn't apply to an AC only system that has no built in furnace...would it? So many quesions about that...with the number one being how did we as a society become stupid enough to accept such garbage reasoning for not being allowed to do something so obviously beneficial. I will do it anyway on my house...
My Man!
Yeah, but what about the gravitational pull of the moon and what if a child climbs in there and gets stuck?
Give me a break.
this is what allows poor architecture and design to persist.