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It only takes a minute to sign up. I will explain what I would "Ideally" want. Plumbing seems possible because the holes for the most part will be small enough to not affect the structural integrity. So the question is what is possible?

There is also a similar post here. They talk about the limits on what can be done to floor joists. From my understanding, it would not be possible to install any ducts through the floor joists. If I am wrong, please let me know. Last would be what is the alternative? Is it possible to run the ducts through the roof attic?

I assume that opens a whole different set of issues Plus that doesn't fix the cold air return which should be on the bottom if I am not mistaken. I would really like to avoid soffits if possible but everything I am researching is pointing that direction. EDIT: The house is an existing home. The basement floor to ceiling is already at the 8' mark.

The joists are typical dimensional lumber not engineered. If I was doing a new construction, this would probably be one of the best options. Its very interesting. I did read there are some disadvantages like noise and it can be costly to add.

The image below is an example of what I had original wanted but it doesn't seem like that is up to standard? EDIT- Image below is a not my current hvac.

Its also a BAD way to do it. Was using it as a reference. You could put in a non-forced air heating system - ie, hydronic or radiant, using water in pipes to deliver heat.

You only need space for ducts if you need ducts, and there are plenty of houses without ducts Edit: you may be able to work with a wide, shallow duct so you can have a broad, not too deep soffit for the cross-joist duct run. Just be sure to get the sizing sorted out correctly ie, a 12x12 duct cannot be replaced by a 3x48 duct same areaas there's a lot more friction in the 3x48, but the correction factors for duct shape are surely available so you could pick a size that will work.

It will cost more, but it may resolve your issues with soffits if you don't have to duck under them. One option would be "low-volume, high-velocity" ducted system manufacturers include SpacePak and Unico that uses a series of small 2" diameter ducts to distribute air. Depending on the size of your joists, 2" holes may be acceptable.

As Ecnerwal mentioned, mini-splits can be a good option too. Sign up to join this community. The best answers are voted up and rise to the top.Sean Mullin has been creating online content since He also worked in an online writing center for college students.

In addition to writing, Sean has a Master of Arts in classics and teaches Greek and Latin part-time at the college level. Running a duct from the first floor to the second involves creating a hole in the main duct and attaching new duct work that terminates in a floor-level heat register on the second floor. Homeowners expanding their existing first-floor duct work to the second floor need more space than walls typically provide, so they must cut a hole in the floor and pass the duct up through the first-floor ceiling.

Boxing in the new, exposed duct with studs and drywall subtracts living space but conceals the improvement. Locate the first-floor plenum or main duct. Choose an area located below a closet or an unfrequented area of the house but close to a basement ceiling joist. Mark a circle on the main duct equal in size to the duct collar.

Make sure the circle faces up toward the second floor. Cut out the circle with sheet metal snips. Fit the duct collar over the hole in the main duct and attach it. Cut a hole in the floor just large enough to accommodate the duct work. Run duct work through the hole. In the basement, secure the new duct work to a joist by running a hanger around the duct and attaching it to the joist. Continue attaching sections of duct work until you reach the ceiling of the first floor.

Cut a hole in the ceiling with the saw, but avoid cutting into the ground level of the second floor yet. Run the duct into the ceiling. Secure it to a nearby joist with a hanger. Attach a T-fitting piece of duct work if you want the new duct to run into many rooms on the second floor. This will allow you to attach new duct work horizontally.Section Building framing cavities cannot be used as supply ducts.

Supply ducts in attics are insulated to a minimum of R All other ducts in unconditioned spaces or outside the building envelope are insulated to at least R Section M Stud wall cavities and spaces between solid floor joists cannot be used as supply-air plenums. Section R Building framing cavities cannot be used as supply ducts or plenums. Get Started. Grow Your Business. Show Menu. Nearly all building codes restrict the use of cavity spaces as supply ducts. However, it has been common practice to use cavity spaces as return-air pathways.

Building cavities used as return-air plenums is one of the leading causes of duct leakage in homes today. Inspectors can learn how air leakage from ductwork may cause home energy loss, increase utility bills, lower comfort levels, and make the HVAC system less efficient. Still commonly used is the panned floor joist. Using floor joists as return ducts by panning can cause leakage because negative pressure in the cavity will draw air from the outside into the cavity through the construction joints of the rim area at the end of the joist cavity.

The illustration above shows a floor joist cavity used as a return-air duct by nailing material, such as gypsum board, sheet metal, foil insulation or OSB, to the bottom of the floor joists.

Some builders create pan joists by attaching a solid panning sheet material to the bottom of a floor joist to create a return-air pathway. Using panned joists is not the best practice because the return-air pathways cannot be air-sealed properly. Cavities or interstitial spaces within walls are also sometimes used as supply- or return-air pathways.

These cavities often create a connection of inside air with outside air from an attic or crawlspace. It is very difficult to make such cavity spaces airtight. When cavity spaces are used as return-air pathways or supply-air ducts, a few issues will arise. Because cavity spaces are leaky, building pressure imbalances across the building envelope will occur, driving air infiltration into the building.

A cavity space used as a return-air pathway will pull pollutants into the building from unknown sources. Another issue with using cavity spaces as return-air pathways is fire safety.

Building materials, such as wood products, do not meet the flame- and smoke-spread criteria as do approved duct materials. Using cavities as return or supply ducts is not a fire hazard in itself, but it will encourage a fire to spread throughout the building. In humid climates, a cavity space used as a return-air pathway will pull humid air into the cavity space, possibly encouraging mold growth or the deterioration of building materials. Other common framing cavities used as return-air pathways or plenums are air-handler platforms, open-floor truss cavities, and dropped ceilings.

Open-floor trusses used as return-air plenums can draw air from any place connected to that floor.

how to run heat duct through floor joists

Air-handler platforms used as return-air plenums can draw air from vented attics and crawlspaces through other connected framing cavities.Subscriptions Media Kit.

Using flexible ducts saves time, but careless installation can cause performance-related problems that are hard to find and even harder to fix after the drywall goes up. On most projects, HVAC ductwork is located in designated chases that maximize the efficiency of the airflow. But the path for the final branch of the ductwork tree—the one that runs from the trunk or plenum to the outlet register—is typically chosen by the subcontractor.

Often, they find themselves competing to find space to run the ducts among all the wiring and piping already installed by the electrical and plumbing trades. Flexible ducts can speed installation by reducing the number of joints in a run and eliminating the need for elbows and offsets. They also easily conform to oval as well as round connectors. A good first step, or course, is to make sure there is effective communication among all the parties involved, including designers, framers, and HVAC, plumbing, and electrical tradespeople.

The details presented here were captured from the U. Airflow is more complicated than it seems, and carelessness or disregard for these best practices can really come back to bite you. All ducts should be sealed using UL—rated duct mastic [1]and flexible ducts should be held in place with tie wraps at all connectors. Ideally, all ducts should be located within the conditioned space. This is typically the case for ducts that run through a dropped ceiling or soffit, or between joists, so long as the floor system sits on top of a conditioned basement or crawlspace.

Attics can be problematic when insulation is located in the attic floor rather than in the rafter bays or, better yet, outside the roof sheathing. When ducts are located outside the conditioned space, they should be sealed to prevent loss of conditioned air and also insulated to prevent thermal loss or gain from the ambient air.

All ducts, whether rigid or flexible, should be sealed with UL—rated duct mastic. Friction is the enemy of airflow. That creates slack in the duct, which reduces airflow for two reasons. To maintain strong airflow, plan for short, straight runs during the design phase.

How to Run Duct Work to Second Floors

Pay particular attention to the framing plan, and route ducts through floor trusses where possible [2B]. Monitor the plan during framing and be prepared to create chases to carry ducts where necessary.

Also make sure that all ducts, regardless of length, are stretched tight between fittings. Avoid taking up slack with sharp bends [2A], which severely reduce airflow. Plan the framing package to include chases or trusses to accommodate ductwork [2B].

Ducts that are not stretched tight or that contain sharp bends can increase the equivalent length of the duct run by several multiples see illustration, above.

Airflow in a duct run of any length can be compromised by sharp turns or even kinks. And each turn, kink, or compression in a duct run reduces airflow, which results in more comfort-related complaints from your customers. Unfortunately, on many jobsites, poor planning of the framing and lack of coordination among subtrades result in all manner of bends and kinks, some of which all but stop airflow completely [3A].

Once the drywall is up, these problems are impossible to locate, so carefully inspect ductwork before the drywall crew begins its work. Kinks are comparatively easy to spot, but a sharp bend can constrict airflow and is more difficult to see [3B].

For example, the center line of a bend in 8-inch—diameter duct should follow a curve with a radius of at least 8 inches [3C].Remember Me? Results 1 to 12 of Thread: Boxing floor joists as supply ducts. Thread Tools Show Printable Version. Boxing floor joists as supply ducts Does the hot air supply have to be in metal ducting from the furnace plenum to the air register, or can I box in the floor joists just below the registers and feed the hot air into the boxes? Aww cmon Guess it does not HAVE to be.

If this is not a joke do yourself a favor and don't diy this project. Why bother with registers? Can you just heat the floor this way?

If you'd like to reach me, leave me alone. I dunno, if it were me I'd just buy an oversized furnace and set it in the middle of the basement and let her rip, screw the plenum! Just think You can thank me later Actually that is exactly what the current scenario is I'm running 40 of rice coal a day keeping the basement and 1st story floors warm forced air circulation kit on the stoveand using almost NO oil. The area is somewhat funky to work in, hence the REAL question about boxing in the joist Yup, I'm a homeowner, DIY'er, but not a hack.

Merry Christmas. Originally Posted by bobsemp. Does the hot air supply have to be in metal ducting from the furnace plenum to the air register, or can I box in the floor joists just below the registers and feed the hot air into the boxes? Thanks; understand your points and appreciate the thoughts. I'm not looking to do a long run 'twixt the joists - 6"round will do just fine for the first 20' I dont warranty Tinkeritus.

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Originally Posted by lolson. The International Mechanical Code does not permit using combustible materials conveying supply air. Perhaps you should have read the instructions before calling.

how to run heat duct through floor joists

Please read this Valves, Regulators, Filters, Etc. Subscribe to this feed. People: December The Unsafe Superstar. Code Quiz of the Week: No.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

It only takes a minute to sign up. But if I add a 5" booster fan would it be possible to retain proper air flow and route this duct through the joist using a 5" to 3" reducer? Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Is it possible to run an HVAC duct through a floor joist?

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Building Cavities Used as Supply or Return Ducts

Asked 1 year, 2 months ago. Active 1 year, 2 months ago. Viewed 2k times. Christopher Christopher 1 1 1 bronze badge. I'd look at splitting the duct into two 3" pipes as it passes through the joist. The added complexity and expense of a booster is to be avoided.

I'm confused about what I'm seeing up there.

how to run heat duct through floor joists

Why is one joist lower than the other? What are the boards at the left end? Both joists are the same height, there are just boards scabbed onto the bottom of one.

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Wouldn't you need more than two 3" pipes to keep the volume consistent? Active Oldest Votes. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.

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Post as a guest Name. Email Required, but never shown. The Overflow Blog. Featured on Meta. Feedback on Q2 Community Roadmap.Remember Me? Results 1 to 7 of 7. Thread Tools Show Printable Version. Ductwork Through 16" Deep Floor Trusses sq. Heat Pump to be used. This will be a newly constructed home not yet started. I was wondering if I could use the chase in the truss to run the ductwork for my 1st floor HVAC blowing down from the ceiling, as opposed to blowing up through the floor if the crawlspace were to be used?

I'm thinking it would be nice to have NO ductwork in the crawlspace. THAT would be awesome: no ductwork in EITHER the attic or crawlspace - just a single trunk running though the very center of the house pushing air upward for the 2nd floor or downward for the first floor!

I'll have the house plan, truss plans, etc. We have done some jobs where the truss joists had the cavities built into them for the ductwork, however it is very important that these spaces be large enough, actually in line with each other not installed backwards halfway across the house! You would need to work closely with your HVAC contractor, and make sure of air flow needs, location of outlets and duct, and also location of returns in order to use this middle truss area to serve both floors.

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Also consider that you may have plumbing in the crawlspace if you live in a really cold area! Since you live in SE area, freezing of plumbing won't be a problem. Most of what I'm going to say is opinion based on houses I have worked and or lived in Mid - Atlantic area.

One thing that has worked for me for heat pump systems is to make the return duct as big as possible Size return duct based on fpm ft at least. Largeopen grills on each level and in each critical area. A two story home is most comfortable when the first floor is supplied from the floor and the top floor is supplied from the ceiling. It's nice if the first floor supply can be oversized a bit to promote slower velocities for heating. Flexible duct is a great thing if you use it in 6 ft sections or less.

Resistance increases due to a lack of understanding or effort from the installer will do you the end user no good. Varriable speed ahu's solve a great many " duct issues ". They work even better on a nice duct system.

All this with a true load calc. More is not always better. Originally Posted by wahoo. Please read this Valves, Regulators, Filters, Etc.

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