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View Full Version : Multiple Fresh air returns, high and low ones.



lionfoxx
Jun 28, 2005, 08:51 PM
Each bed room in my house has heating vents on floor, 2 rooms have 2 and 2 rooms have 2, but each room has return air vents , 2 each in each room, one off the floor about a foot and the other about a foot off the ceiling.

I notice when painting and removing that someone had taped certain ones closed to block the return.

I was told that I should spend the money and not get the basic open vent ones, but to go the little extra to get the ones you can turn off and off with the flip lever. The guy said that this way you can open the top to suck off hot it in the summer and close it in the winter and open the bottom to suck in cooler air, etc. This is suppose to help heat and cool the house better. I can understand the concept but is this a good idea or will it make the furnace or AC work harder?

Hot air off the top with bottom one closed in the summer, and top one closed in the winter with bottom one open to get the cold air after the heat has rose up from the heating vent.

Any method to this maddness or do they not work that way?

Flickit
Jun 29, 2005, 05:18 AM
Each bed room in my house has heating vents on floor, 2 rooms have 2 and 2 rooms have 2, but each room has return air vents , 2 each in each room, one off the floor about a foot and the other about a foot off the ceiling.

I notice when painting and removing that someone had taped certain ones closed to block the return.

I was told that I should spend the money and not get the basic open vent ones, but to go the little extra to get the ones you can turn off and off with the flip lever. The guy said that this way you can open the top to suck off hot it in the summer and close it in the winter and open the bottom to suck in cooler air, etc. This is suppose to help heat and cool the house better. I can understand the concept but is this a good idea or will it make the furnace or AC work harder?

Hot air off the top with bottom one closed in the summer, and top one closed in the winter with bottom one open to get the cold air after the heat has rose up from the heating vent.

Any method to this maddness or do they not work that way?
... a logical placement of the returns but will be a problem if by closing one of the returns the design minimum volume is violated. The system will work harder if this is the case. Can you check in the crawl space to see if the 2 units/room are joined (T) before returning to the A/C?

lionfoxx
Jun 29, 2005, 05:32 AM
...a logical placement of the returns but will be a problem if by closing one of the returns the design minimum volume is violated. The system will work harder if this is the case. Can you check in the crawl space to see if the 2 units/room are joined (T) before returning to the A/C?


Yes I believe they are connected, My dad had the same concern if it would make the furnace work harder?

labman
Jun 29, 2005, 06:38 AM
The system has worked with some of the vents taped over. Changing over to a system of opening and closing them, shouldn't make much difference. A blower actually does less work with a more restrictive intake. The more restrictive the intake, the lower pressure the squirrel cage turns in, using less power. A more efficient air flow should require the system to run less saving both money and wear.

I think if you check, you may find the studs and drywall form the duct in the room wall, and it just has 2 holes in the same wall cavity.

lionfoxx
Jun 29, 2005, 09:06 AM
The system has worked with some of the vents taped over. Changing over to a system of opening and closing them, shouldn't make much difference. A blower actually does less work with a more restrictive intake. The more restrictive the intake, the lower pressure the squirrel cage turns in, using less power. A more efficient air flow should require the system to run less saving both money and wear.

I think if you check, you may find the studs and drywall form the duct in the room wall, and it just has 2 holes in the same wall cavity.
****

Yes there are 2 wall holes, both lead down to same vent draw tubing, I was understanding that in the winter the hot air rises and pushed cold air to floor so you close the top vent and open the bottom one, and in the summer you want the top vent open to pull the hot air off the upper part of the room and you close the bottom one.

So would you consider this more restrictive, and also more efficient? The regular vents without shut offs are probably less than half the cost, I would rather spend the money and get the better ones so I can regulate the vent depending on the season, I can use the type that can be shut off for 3 bedrooms and in one room I have to use the cheaper flush mount type because it has a wall stud blocking the deeper vent.

Thanks,

Frank Mangrum
May 13, 2012, 01:27 PM
Each bed room in my house has heating vents on floor, 2 rooms have 2 and 2 rooms have 2, but each room has return air vents , 2 each in each room, one off the floor about a foot and the other about a foot off the ceiling.

I notice when painting and removing that someone had taped certain ones closed to block the return.

I was told that I should spend the money and not get the basic open vent ones, but to go the little extra to get the ones you can turn off and off with the flip lever. The guy said that this way you can open the top to suck off hot it in the summer and close it in the winter and open the bottom to suck in cooler air, etc. This is suppose to help heat and cool the house better. I can understand the concept but is this a good idea or will it make the furnace or AC work harder?

Hot air off the top with bottom one closed in the summer, and top one closed in the winter with bottom one open to get the cold air after the heat has rose up from the heating vent.

Any method to this maddness or do they not work that way? Assuming that each high and low return in these rooms were designed to handle all the required air flow of the area it serves-then one return could be turned off and the other opened. If this is the case then open top return and close bottom return in heating mode. This pulles the warmer stratified heat from ceiling area back to heating unit and is heated to a higher temperature than using cooler return air near floor. This warmer output from heating system will heat the comfort zone (the lower half of room that people occupy) much faster with less energy because we are using the warmer stratified heat at ceiling for return air. Close the ceiling return and open the floor return in the cooling mode. We want to stratify heat in ceiling during cooling mode after all we don't occupy the ceiling area just the lower half of the room (comfort zone). When the cooler air from floor area is used for return air and is returned to cooling coil this air will be cooled to a lower temperature than using warmer stratified heat in ceiling area for return air. This cooler air discharded from cooling coil will quickly cool the comfort zone leaving the warmer stratified air near ceiling in place, after all we trying to keep people cool and not the ceiling.This techique will decrease load on cooling system and save energy.