ReplyWarm air rises so you would nbe right. But, be sure you will have enough return air before closing anything. It could be a second return air was installed to fix return air problems.
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Greetings all. We live in Wisconsin and our home was built in 1994. It's a 1700 sq. ft. ranch with AC. There are cold air returns near the floor and near the ceiling. However the ones near the floor are the only ones that can be closed. Is this right? Or should the closeable ones be near the ceiling? To me is seems to be backwards. It just seems to me that you would want the ones near the ceiling closed in winter so you aren't pulling warm air back into the furnace. What do the pros think?
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Warm air rises so you would nbe right. But, be sure you will have enough return air before closing anything. It could be a second return air was installed to fix return air problems.
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Nope, we are the original owners and it's been like this since new. I guess what I am trying to say is this: Should both have the ability to be closed? And if only one can be closed, shouldn't it be the top one?Originally Posted by timjimbob
Professional Member*
Assuming your furnace is in the basement, the floor returns probably pull more air by proportion, year round. This is due to each one being closer to the blower intake than the ceiling return, so there is less pressure drop in the duct.
I would leave the dampers fully open until it can be determined that the system has enough return air volume with one or more sets of dampers on the floor returns closed. I wouldn't do anything about it at all if the house is otherwise comfortable.
Psychrometrics: the very foundation of HVAC. A comfort troubleshooter's best friend.
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With a properly sized air distribution system with high/low return grills the floor level grills should be open in the winter (heating mode) time and closed in the summer Cooling mode) time.
A good HVAC tech knows how, an educated HVAC tech knows why!
DEM
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Leave them both open year round for increased airflow and increased life of equipment.
AOP Committee/Professional Member*
In Wisconsin, like in north east Ohio, gets pretty cold. The return air grills at floor level will bring the heat down to floor level from the ceiling, where you want it eliminating those pesky cold drafts. That's the reason for the high/low configuration other wise they would just cheap out and make them all high. It's done that way for added comfort. If it's sized properly, and odds are if they went to the extra trouble to do it in the first it is, then take advantage of the feature.
A good HVAC tech knows how, an educated HVAC tech knows why!
DEM
God Speed, Jim. We'll miss you - 2-26-23
Leave them open year round.
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Right. But is it right to have the ones with the closing flap near the floor? Or should the closeable ones be near the ceiling? See what I am saying? There are two vents but only one closes. Where should the closeable one be?
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They should both be closable but it depends on heating or cooling climate which one you would do rather than the other. A primarily cooling climate the bottoms should be closable and primarily heating the tops should be closable, or both would be good or neither I think would be best.
After thinking about it, if the furnace is below the space then if the return duct/grills are properly sized then most of the return air would naturally come from the bottom grills since they are closer to the unit unless you closed the bottom then it would pull more from the top due to air flow (energy) taking the path of least resistance.
God Speed, Jim. We'll miss you - 2-26-23
Don't mater which ones have the dampers. leave them open year round, don't close off any of them.
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The lower ones having the ability to be closed was the "thinking" of the installing contractor and not something that is considered normal or standard installation practices in my opinion.
A properly designed and functioning system for a home that has needs to both heat and air condition to opposite extremes can take advantage of both high and low returns year around.
The only operational issue that might come into play with high and low returns is if they are using the same stud wall cavity. A standard interior studded wall has only 3 1/2" of space and if the damper from the lower register extends into this space when it's open it can block off the ability for the air to easily pass from the upper register. With some register designs (a single flap verses multiple small louvers) it can totally block off the air from the upper register. If the installer was "old school" from the days of gravity systems in 2 story houses, he could have installed the single flapper design to be able to block off the upper unit in the winter. I've seen plenty of these old style stacked systems here in wisconsin.
Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.
AOP Committee/Professional Member*
If the lower ones are single flap (as I guess they are), When they are "open", the flap extends into the wall cavity effectively "closing" the path of air from the upper grill. If they are of multi louver design, then closing that grill only limits the intake of that grill.
A good HVAC tech knows how, an educated HVAC tech knows why!
DEM
New Guest
They actually the louvered style so they don't protrude into the duct more than an inch or so.
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I've seen a few homes like that here in MN with this set up, and I have this in my hallway.
I close the lower one in the summer, and open in the winter. In a way, i am glad to see that set up in this home. With it open in the winter, it will draw the cold air off the floor in the winter, and then in the summer, closing it will then use the upper one to draw the warm air from the ceiling.
God Speed, Jim. We'll miss you - 2-26-23
Try leaving it open in the summer. Might find it gets you better air flow, and mixes the room air better.
Professional Member*
Ok, now that all the facts are in.........
Your concern was (as I understood it) why wasn't the closeable register put near the ceiling so that you could stop heated air from being returned to the furnace.
If the home's HVAC system was installed correctly: Within a short amount of time of the furnace's blower coming on (during a heating cycle) the movement of air within the rooms quickly "mixes" all the air in the space. Very little temperature difference will exist between the air temperatures at the floor and ceiling. During cooling season this doesn't happen as efficiently because the cold air being delivered to the room doesn't "circulate" as well....... for a lack of a better term to use that is easy to visualize.
Heated air will rise by nature. If you've paid to heat that air during the on cycle of the furnace to keep you comfortable it will only accomplish this when the blower is running. As soon as the blower stops the cooler air in the room sinks and the heated air rises. The heated air rises above your head...... only thing it's doing up there is warming the ceiling and trying to get out of your home. The returns near the ceiling will pull this already heated air back to the furnace and redistribute it.
Properly designed, installed and controlled multi-zone HVAC systems take advantage of this and can actually move warmed air (via solar gains as an example) from one zone that is exceeding it's set point to one that is in need of more heat by only turning on the blower and never running the furnace.
I wouldn't be concerned with the dampers being only in the lower returns. Every home and it's occupants live and function differently. What you have is the ability to manually modify your system in a way that very few others do. Experiment with opening or closing the dampers and see what works best for you and your home. The results can be surprisingly different between different rooms in some cases. Would I suggest putting dampers in the upper returns...... no. You'd see no advantage in energy savings or comfort IMO.
Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.
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I did do that one summer, and it made it warmer up there since the hall way is getting the heat from the living room, kitchen/dinning room. So the comfort was better with it closed in my case.
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