Home Air Circulation

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  #1  
Old 11-12-18, 09:51 AM
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Home Air Circulation

I've been trying to figure out why some of my upstairs rooms are colder than others in the summer with the AC running and warmer with the Heater running. Everything I read points me to the dampers bit I can only find 2, both of which are in the basement. There is a furnace in the basement and one in the attic. I originally thought one went to one side of the downstairs and the other to the far side of the downstairs and would have a separate set of dampers in the attic but I don't see any. What is the best way to set these?

 
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Old 11-12-18, 09:57 AM
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Generally a furnace or ac in the attic serves the upper floor with registers in the ceiling. Usually an attic unit is not there to serve one side of a house. The furnace AC in the basement usually serves the main floor with registers in the floor.

First, you need to figure out what rooms each furnace AC serves. Leave one turned off and then turn the fan on for the other unit. Then go around the house and note which registers are blowing air. Once you have what each furnace covers mapped out you can try closing one damper and opening the other. Then go back through and note which registers are blowing air strongly. Then switch the campers to find out what the other one controls. Once you know that you can start to put together a plan.
 
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Old 11-12-18, 10:03 AM
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https://drive.google.com/file/d/1pA6...w?usp=drivesdk


This is a pic for the two dampers in the basement straight off both sides of the trunk.
 
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Old 11-12-18, 12:51 PM
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Thanks for the reply. I'll start here. To clarify, should there be a similar damper setup in the attic?
 
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Old 11-12-18, 01:59 PM
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No, all the dampers would be off the main line!
 
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Old 05-26-19, 05:17 AM
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Upstairs hallway heating

It's been awhile for this but I still haven't figured it out. I asked the last ac guy about them and he explained basically the same thing as you guys did. The problem is that testing them by opening one and closing the other does nothing for the upstairs. Closing one cuts airflow to downstairs vents to the left downstairs and the other works only the right side of the house. I checked vents upstairs..nada for either. There is a furnace in the basement and attic. Ac guy said everything was working fine airflow wise.
 
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Old 05-26-19, 07:08 AM
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Ok, you now know that the attic furnace controls only the attic, assuming I read it correctly.

From your initial description some rooms upstairs are colder in the summer than others (cooling mode) and some are warmer in winter (heating mode).

Is it the same room that is too cool in summer and too warm in winter? If so that room is receiving the majority of the attic furnace air?

Have you been into the attic to see where the ducts up there are going? Pictures?

Bud
 
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Old 05-26-19, 07:39 AM
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I'll get up there and take some pics of the ducting today. You are correct though. The same rooms are affected in the summer and winter. The hallway up stairs has the one return and is always warmer as well. It literally smacks you in the face when coming from downstairs.
 
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Old 05-26-19, 07:48 AM
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With the return in the hallway each room can end up with limited air flow when the door is closed, especially if a carpet is sealing the bottom of the door. The room that has seasonally hotter (winter) and colder (summer) conditions may have a good gap under the door or the door may be typically be left open while the other rooms are more closed off.

Bud
 
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Old 05-26-19, 08:13 AM
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So this could be as simple as keeping the doors open? There are 5 bedrooms upstairs, mostly home to teenagers that always have it closed. Even if I manage to get their rooms cool at the end of the day, the hallway is warm.
 
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Old 05-26-19, 08:40 AM
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The hallway is always going to be fighting physics and only a circulation effort can move that warm air down.

An alternative to leaving doors open would be adding returns to each room. Typically each room should have larger returns than supply to prevent excess pressure from forcing conditioned air out through the walls and around windows, But that is another project.

Undercutting doors or adding feed through grills between the rooms and the hall can also help but can create a noise problem.

In addition to the distribution of heat and cooling there may be problems with the insulation and air leakage in other rooms. When the system cranks up to compensate for heat loss and heat gain it over cools of over heats the one room that is better insulated.

Is the room that is perceived to be a problem a corner room of interior room with only one exterior wall and one typical window?

Age of house and your climate region could help.

Bud
 
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Old 05-26-19, 08:53 AM
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Is the room that is perceived to be a problem a corner room of interior room with only one exterior wall and one typical window?

This is correct. The ac guy simply said there was enough flow to both rooms. With that, I assumed it was something we were doing...or not doing.

Age of house and your climate region could help.

The home is in NE Virginia and built in 2007
 
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Old 05-26-19, 09:15 AM
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Are you referring to something like this?

https://www.homedepot.com/p/Tamarack...E&gclsrc=aw.ds
 
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Old 05-26-19, 09:46 AM
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I had an "of" in there instead of an "or" so when you said correct I'm not sure which one is correct. I doubt out language will ever survive .

"The ac guy simply said there was enough flow to both rooms." Before he makes that conclusion he should evaluate the heat loss and gain in all rooms up there.

Being a 07 home I suspect it is well insulated but look around when you are in the attic to be sure all is well covered with insulation. Windows should also be double pane and reasonably efficient. Unless there is a hidden problem you are on the right track of chasing down the distribution and possibly balancing it to match the particular rooms.

And yes that link is what I was talking about. In some cases one side is installed high and the other low so sound doesn't have quite the direct path.

Bud
 
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