He's not a professional and he doesn't know the most basic things about fluid, yes air is a fluid, dynamics! Supply air from furnaces and air conditioners should be on outside walls.
The return air vent openings need to be on the opposite side of the room so the conditioned air is pulled across the room. If the supply ducts are in the floor, then the return air should be located up high. This pulls the air across your body. If the supply ducts are high or in the ceiling, then the return-air ducts or grills should be low on a wall.
Yes, if your house is either hot or cold, I'll bet you have inferior or lacking return air ducts. If you live in a home that has rooms that are either too hot in hot weather or are cold in cold weather you could have a return-air duct issue. Return air ducts are necessary for just about every room. However, there are two rooms that I never place return air ducts - kitchens and baths. Let's try to keep the garlic odors and hairspray in these rooms if you don't mind! The reason for return air is simple.
Your furnace is simply a recirculating pump. Instead of pumping water, it is pumping air. We need to get the air back to the pump. Furthermore, without a return air duct in each major room, the supply duct air has to "push" all of the air in the room out of the way as it makes its way towards you. The return air ducts help pull the air as it is being pushed.
An HVAC return air can be in the floor, but they work much better on walls up about 7 feet. It's best to put them on an interior wall across the room from the supply duct. If you have an existing ranch style home, installing return air ducts in each room can be done fairly easily.
You do what we do in new homes. You use the wall cavities as the duct. Think of it. Drywall that is nailed to 2x4s is really a duct - a box with 4 sides. All you have to do is cut out the floor immediately below the wall cavity as well as the bottom wall plate. Once you have created the opening, sheet metal will allow you to connect this to your existing return air system. Two-story houses can be more of a challenge. You have to figure out a way to get return air from the ceilings of the second floor to the basement or furnace room.
Do you have a laundry chute that you don't use that often? Can it be sacrificed for the cooling cause? We have used these with tremendous success. Sometimes, you can use a kitchen pantry closet or a hall closet. We have often been able to put a duct in one corner of the pantry or closet. This duct extends up to the second floor where it often lines up with an interior hallway wall.
Often you can collect the ceiling air through a network of flexible pipes in an attic. These pipes join together in one central location that permits you to run a duct down to the basement or a second-floor closet.
As a last resort, you may have to put a duct in the corner of a room s. Here in Iowa we put a returns in almost all bedrooms and all other living areas in the house. My question is can you cause a zonal pressure problem or any other comfort issue by having a strong, over sized return in one room and and a return in another room that is sized only to handle that room?
Will an over sized return effect the return or comfort in another room? What are your thoughts on over sized or unbalanced returns? Austin, you pose an Austin, you pose an interesting question. My initial reaction is that an oversized return in one room would only have a meaningful impact on another room IF the return path from the other room is undersized relative to its supply. Ignoring any interaction with envelope leakage, keep in mind that return side imbalance in of itself is only an issue to the extent that it impacts supply side balance.
The reason is that a properly designed duct system will have much smaller resistance on the return side than the supply side. This would be easy to test by partially covering the oversized return grille and measuring any difference in the zonal pressure in the other room as a proxy for airflow to that room.
If this results in a meaningful change, I would argue that the problem is not the oversized return, but rather that the other return is undersized. In any case, restricting a return in one room to force more air to another room is a bad idea. Much of what you write is over my head, but I have also found articles I actually understand!
We put in tilting transom windows over our bedroom doors. I like the way they look and I suspect they are serving the purpose you are discussing. However, our HVAC vents are in the ceiling. Are we working against our heating and cooling system by having the return up high? We shut our doors to keep our cats out.
I think the cats would rip up any lower door insert. They destroyed the bottom of our bedroom doors; we added metal plates. I thought that was hogwash, and then found out it was true, by reading your information.
I continue to find your articles interesting. Now we are redoing a small duplex for retirement. The cats are coming too. I guess I better look at adding transoms or something to the remodel plan. Is it better to have the return air ventilation low? Cyndy, what a great idea! My Cyndy, what a great idea! The supply air is at its greatest velocity as it exits the diffuser, so the location of the return path is largely irrelevant as long as the supply air is not directed toward or in close proximity to the return path.
Conservatively, you want at least three feet of separation, and make sure the vanes on the grille are not aimed toward the transom.
NFPA now recommends that people sleep with doors closed to slow fire smoke. Heat and smoke rise and will travel right through jump ducts. I would like to see smoke dampers tied into fire alarm systems or transfer grills at the bottom of doors.
Thank You for your time and expertise. If not, take the shop vac to the garage or doors, reverse the hose and blow through the baffle using the reduction tool to concentrate the airstream comes with most shop vacs, although not necessarily referred to as such. David, you are absolutely David, you are absolutely correct.
This whole conversation This whole conversation leaves me with a new invention Thanks everyone! Do you put those on both Do you put those on both sides of the door or only the inside of the door?
Does it need more space around it and how much should we allow? I live in a year old home in the PNW that has some disappointing characteristics in the duct design.
The main floor has 3 supply and 3 return registers all on the floor , but the supply is interior and returns are under windows along the exterior. Thankfully our climate is pretty temperate here. That said, I am looking at installing central air before summer hits. There are zero return registers upstairs 3 bedrooms, and 1 bath. Do you think this may be the case? Should I look at other means given our relatively mild summers? Do you make this product for Do you make this product for ceiling cold air returns for commercial buildings.
I have a question as a I have a question as a homeowner. Our home was solidly built in Over time, the garage was converted into a bonus room, which put stress on the HVAC unit. In addition, the main living area was opened up.
Our return is in the hallway leading to the bedrooms. We recently had the HVAC unit replaced and upgraded to adequately condition the home to include the total square footage of the home. We have pets and close our bedroom doors. The master gets warmer during winter and other bedrooms noticeably cooler than the rest with doors closed summer is opposite.
If you really want to get the most out of your duct system, you should consider installing dampers on both the supply and return vents.
This is something that can be done after the initial installation as long as you can access the ducts, which will usually be located in the crawlspace, attic, or basement. Sometimes you can even use the grill cover to cut down and open airflow, but the whole process will be more efficient with dampers.
Installing these dampers will allow you to choke down rooms that are located too close to the return duct. These rooms will be pulling the most air and taking away suction power from the rest of the system.
If you make careful not you will probably notice right away that most of your supply ducts are either installed by the windows or doors. This is because this is where most heat enters the home. The ducts are installed strategically in these locations to help battle this heat loss or heat gain. And, this is just one of the reasons that the return ducts need to be installed directly across from the supply vents. When installed in this fashion it will allow the system to suck the air throughout the entire room.
Of course, this setup will only be applicable for individuals that are installed returns in every room of the home. If you are going with just one or two return vents you will want to install the return vent in a centralized location as possible.
Another thing to consider is the physical location of the supply ducts. Are they installed on the floor, wall, or ceiling? If the supply ducts are in the ceiling or high up on the wall, you will want to install the return ducts or grills as low as possible. This once again will go back to the old theory of pulling the air across the entire room.
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