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-   -   Will adding a return make a noticeable difference? (http://www.diychatroom.com/f17/will-adding-return-make-noticeable-difference-166746/)

thundercats 12-17-2012 09:48 PM

Will adding a return make a noticeable difference?
 
My one year old's room is cold, and I hope you can help. The HVAC co that installed our furnace says adding a return will solve it, but I'm suspicious that they're just trying to sell.

The room:
-13' x 9' on north side of house near Chicago
-Second floor (below insulated attic)
-3/4 walls are exterior (packed with cellulose)
-1/2 the room is above the unheated garage (its ceiling packed with cellulose)
-4 single pane, double hung windows with new storms, on north and west
-2-4 degrees colder than the other rooms and worse during winter nights

-Zoned gas furnace in vented attic (there was no option, but it's in an insulated closet and we have no ice dams)
-Each bedroom has 2 supply vents at exterior walls, plus 1 in hall and each bathroom
-Only 1 return in the ceiling of the hallway. It's far enough from the supplies that rooms, except the one, are great year round. The bedroom in question is the furthest from the return by far (good or bad, IDK).

The options:
-$150, gets me a Vornado iControl space heater (fire dept said it was safe, and Consumer Reports gave it the highest "fire safety" and "hot spot" rating)

-For much more, a return could be added at base of the bedroom across from the supplies (great position). No repair work needed as they'd be converting a disbanded return to the basement.

If adding a return makes a permanent, real difference, then great. I'm afraid it won't. I did a paper/TP test at the base of each door, and the flow from each room seems the same. If the flow of the bad room was slow, then I'd believe that a new return would matter. I told the TP test results to the HVAC co, and they said the room just needs *more* cold air taken out when the heater cycles on.

What say you? Will a return really matter? Should I just get the space heater? Is there other info that would help you help me?

Thanks! I'm really looking forward to some advice.

concretemasonry 12-17-2012 10:21 PM

If you do not have a good functioning return, the heat will not get into the remote room, especially on the north side of a Chicago home where there is no solar benefits. Without a return, there is no real suction to draw the TP and let the heat in.

On a cold winter night in your area, a plain sheet hung over the window will do more good than all the gas you can get into thermal windows because there is always radient heat loss the is not affected to any extent by fancy windows.

thundercats 12-17-2012 10:41 PM

Thank you for the quick reply!

-I do have wood blinds over the windows. Would that have the same effect as a plain sheet? I need to see if I can just put up the plastic sheets, too. Those slipped my mind

-To be clear, the paper and toilet paper DID fly under the door with the central return on, which indicated to me that there IS air flow. I was actually hoping that the TP wouldn't fly under the door, because then I'd feel comfortable thinking, "yep, this room needs a return b/c it has no circulation," but that's not what happened. The TP was just sucked under the door of the remote room with, at least to my eye, the same force as the other rooms. Does this mean that I just need a separate space heater, or is it possible that it needs *more* return suction than the other rooms because of the bedroom's cold nature?

(I don't have gas filled thermal windows, just the old single pane double hung original to the 1920 house and new, snug storms).

beenthere 12-18-2012 04:20 AM

Since that room has 3 exterior walls and part of it is over the unheated garage. it needs more air flow then the other rooms. So if it only had as much air going under the door as the other bedrooms, it doesn't have as much as it needs.

You said its worse at night then during the day. So is the door open during the day and close at night. This would indicate that you don't have enough air flow to or out of that room. Adding a return to it should bring the room temp up at night to what it is during the day, may not be warm enough though. May still need to choke back a register in the other bedrooms to help get enough air to it.

bobinphx 12-18-2012 08:10 AM

First off my situation is exactly backwards from yours. I live in phx and the upstairs south side bedrooms were very hot at night in the summer time. The kids like to close the bedroom doors at night. During the day, the rooms were fine, but close the doors and they got hot. My solution was jump ducts in the bedrooms, out to the hallway where the returns are. It made a total difference and cost very little to do. I even made it pretty so that my wife was happy with how it looked.

the bedrooms are side by side, with a jack and jill bathroom between them I put the jump ducts low to the floor on the bedroom walls, directly into the bathroom. I then used the area behind the cabinet to install two more low to the floor vents out to the hall. so with the bedroom doors closed, the air flows into the bathroom, then out the bathroom to the hall. note that the bathroom has a separate bathtub, shower and stool room, so various smells do not get moved around the house!!! I bent up my own sheet metal to line the vent penetrations,so that air did not escape into the wall cavity.

Prior to the jump ducts being installed, I closed the bedroom doors and used a stick of incese to find air leaks. The outlets were all allowing air to escape the rooms. additionally, all around the outside (and to a lesser extent the inside) wall to floor crack was leaking too. Interesting that the carpet was always a little dust around the baseboards, which I chalked up to the kiddo's being lazy with the vacuum!!!! after the jump ducts were in, I could not find any outlets or floor cracks that were allowing air to get out. I did seal up the outlets and will, when the carpet gets replace, caulk up the wall to floor cracks. the really intersting part is that you can really feel the air blowing out the vents with the doors closed!! if you are barefoot, you can feel it just walking by!!!!

Bottom line, the rooms are no longer hot with the doors closed and the cost was less then 75 bucks (I used fancy metal vent covers that my wife liked, thus the little bit higher then I thought it should be cost!!!!)

so there you go... I suggest adding jump ducts before you go to the expense of the new returns....


I would be happy to send you pictures.


bob in phx.

Missouri Bound 12-18-2012 08:55 AM

I think I know what "jump ducts" are. But not all the readers of this forum may understand that term. And I agree that it's a very good idea and something most homeowners could do themselves. But if the door to the room is left open to the hallway with the return that itself should make a difference...does it? If leaving the door open is an option then a return or a "jump duct" won't be needed. I (personally) would find, buy or borrow a laser thermometer and find out where the infiltration is coming from. Being over a garage seems to be the culprit. Stick a digital thermometer, cooking type is fine and see what temperature is coming out of those bedroom vents. Do they run through the floor or ceiling? Do they run through uninsulated space or are they uninsulated themselves? What about the airflow out of these vents? There are booster fans for ducts which help greatly. Properly designed systems rarely need duct retrofit, more often fine tuning.

bobinphx 12-18-2012 09:17 AM

Missouri Bound you have far more experiance then I do. I am only speaking from my limited experiance in my own home and those of others that I help.

now, I hope you (Missouri Bound) find this next part funny!!

As to keeping the door open at night, Please Missouri Bound I invite you to come and try to get a 16 year old girl, with a speech and debate background to leave her bedroom door open at night!!!!! I am a parent who does invoke the old school ways of raising kids (dusting off of the seat of their pants was always an option), but I must say, I lost the door open battle!!! her reasons and debate skils won out on this one!!!! LOL

so for others who might wonder about jump ducts.
The idea of jump ducts is to allow an path for air to exit a room, with ease, and return the air back to the intake of the HVAC unit, without the expense of an additional return ducts. This works well for homes where running return ducts would be costly or impossible (flat roofs come to mind!)

Please feel free to add any further descrption of jump ducts!!!

To the OP,
I would also like to add that sealing the duct to wall (or floor) gap with caulk and or duct mastic would help also. Additionally, sealing as far as one can reach into a duct is a good idea too.

bob in phx

thundercats 12-18-2012 10:37 AM

Thanks so much for the thoughts thus far. A few responses:

1) We have sealed everything we could (floor to wall gap, around and inside ducts, etc)
2) The supply ducts are insulated and also are covered in attic insulation
3) The supply vents pump basically the same amount of warm air in this room as do the other bedrooms. This room has its own trunk line from the furnace due to its location....would an inline booster fan make a difference then or not really b/c all the heat in this trunk line is already going to the problem room?
4) Based on the layout of the room, and the preexisting old return duct (in a wall cavity behind a curved stair, in which the laundry chute runs, I think it might actually by physically easier to add a return (albeit more $), than to add a jump duct.
5) I'll try keeping the door open at night, although it makes sleeping through the night more difficult on all three of us. However, I don't think it's a good solution long term. The one thing this room has going for it, as it is colder and smaller than the other bedroom, is a bigger closet and more privacy.


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