One room substantially under heated/cooled

Old 01-28-15, 05:37 AM
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Question One room substantially under heated/cooled

Where does this question belong? Hopefully here.

Each room in my house pretty much has direct ductwork to it from A/C unit. One room on the opposite side of the house always seems to be less warm in winter and less cool in summer than the rest of the house. Unfortunately it's the kid's room. I've been using a room heater during the winter and keeping the house much cooler in the summer than I would like in order to keep the room at a decent temperature.

Is there some way I can fix this? The damper is open all the way. What about one of the in-line duct fans? Do they do any good?

Thanks for any help.
Old 01-28-15, 08:41 AM
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First examine the duct leading to that room. Make sure it is not crushed or kinked which can reduce the airflow. Also, keeping the door open will allow the air to get back to the return easier which will also increase the airflow. Other than that you can add another duct or replace the existing one with a larger size or add a booster fan like you mentioned.
Old 02-11-15, 12:04 PM
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I have the similar problem. It's a brand new house (2700sf ranch) with 6" walls that meets all these new "energy efficiency" qualifications. Which so far seems to mean "doesn't move the air very well".

The south side of the house (master suite) was 7 degrees hotter during the sunny days than the rest of the house is. You walk from that room to the living room and it's like walking past an open oven to an open refrigerator. It's that way both during A/C months in the summer and heating months during the winter.

First thing I did was to leave the furnace fan on full time. That helps circulate the air better, but it still only puts a dent in the temp gap.

Next thing I did was research the furnace and found I could increase the fan speed. A/C was already on the fasted speed (which is normal), but heat was wired for MED-LO, so I switched that to MED-HI to get more air movement. Marginal improvement.

Next I installed an in-wall fan to move air from the cooler laundry room adjoining the MB. There's about a 4 degree difference between those rooms. With the MB door open, that should circulate the air completely around the house in a circle. But at only 85 CFM it's a slow process. I have that fan on a timer running daylight hours.

Which brings me to closing off return vents in the MB. There's 2 return vents (one high, one low) in the MB. The rest of the house has a total of 4, although 2 of those are big ones (like 3x the size of the others). If I block the 2 in the MB, there's a very noticeable increase in the air flowing out of the MB door into the rest of the house. Which is the best way I can think to equalize the air temps from one side of the house to the other. But I don't know if it's putting extra/too much strain on the furnace fan by doing so. Is there a way to tell?
Old 02-11-15, 12:15 PM
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Closing the returns means less air is moving out of the room. Even though you feel more moving through the doorway, you've now made it harder for the air being dumped in to leave to equalize pressures.
Old 02-11-15, 01:21 PM
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But if I make sure there's a way for the air to exit the room into the rest of the house, it should just flow that direction instead, right? Seems like the only limiting factors would be (a) not a big enough opening to leave the room, or (b) not enough return vent capacity in the rest of the house for the furnace to suck in enough air.

I should be able to accommodate (a). It's (b) I'm concerned with. There's two 14"x14" and two 6"x12" return grills on the "cool" side of the house. The 14x14 closest to the furnace sucks in by far the most air (I can tell by placing a sheet of paper near it to tell the flow is much higher there, as well as more lint/dust). The 14x14 about 15' further down the hallway doesn't draw near as much air in, nor do the two 6x12's, which seems to suggest that there's still sufficient capacity available.

The goal is to move much of that hot air from the MB into the rest of the house (or at least the living room it adjoins). I'm hoping that pushing it more directly through the doorway will do a better job than what's happening now. It would also have the added benefit of dumping that warm MB air directly into the cool living room.

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