Ductwork return air question or two

David... wrote: ↑

Sat. Dec. 09, 2017 9:35 pm

One of my systems has only one return and it is not too warm around the return grille. Try closing down the supplies for the room that is too warm.

David

I do agree with this though, which again is why I was wondering how close the closest warm air supply register is...

Windyhill, the room with the cold air return should theoretically be the coolest room in the house. Since by the time the warm air leaves the registers it is mixed with the air in the house, which has been exposed to cold air infiltration from outside and that has also given up some of its heat thru conduction from exterior walls around the perimeter of the house. The coolest air in the house needs to return to the furnace to be heated up again. This is also why cold air returns are located on the floor, cool air sinks. If only one big cold air return exists it should be centrally located in the house close to the bottom of a stair case if in a two level home.

If the coolest air in the house isn't returning to the furnace then the warm air supply registers need to be tweaked or relocated or more cold air returns need to be added to the system.

you can try his idea. just pan the the floor joist out for the right size return duct. if the small restriction of the 3.5 x 14 going thru the floor proves to be to much box out into the room and make opening larger. when running flex duct up a size due to inherit flow loss. trailers are known for undersize ducts. they no how to save a penny!

I have to agree with Lightning, only because I have the same situation with a single 24"x24" CAR in my wife's 12' x 12' art room between the garage and living quarters. (Heating with the LL AK 110)... I also have the register closed off in that room...Temperature in the house (T-Stat on an inside wall) stays constant within 1 degree of set point using the CoalTrol. Temperature in the art room is about 2-3 degrees cooler than the rest of the house with up to 1800cfm of cold air passing through this room. Keep in mind that there is no door on the entrance to the Art Room, so air is allowed to pass through freely...The OP did say his CAR was in a closet in his bedroom. Maybe he is closing the door at night which would keep the cold air from making it back to the furnace from the rest of the house?? He didn't say... This could create the issue he is seeing. Try leaving the door open at night.....Just my 2 cents....

Sorry guys, I should have waited until I came back from vacation to have started this thread. My closest register to the present CAR is about 5'. That is why I'm assuming we get so hot in bed, no pun intended. Have tried closing the heat vents, didn't make a whole lot of difference. Much of this heat problem probably stems from the amount of time spent heating. In the summer I can reach over my head and gain 10°F just from solar gain. In the winter I make some awesome icicles. For the time being there is no repairing that issue, cathedral ceilings throughout. Short of adding depth to the ceiling/roof with 2X10's or the like, it is what it is.

As for just leaving the door open that helps except that I have a young lad that used to like to make a bite to eat at 2AM. Kitchen is right outside our door. I like to sleep when it's dark. Also, the hounds aren't afraid to come in at any time of the night and launch onto the bed.

I'm very limited in where I can cut into a wall and even more so a floor for a CAR. Otherwise I'd drop one in the middle of the house floor. And being a double-wide with a marriage wall that limits me even more. Then you have to watch out for the carrying beams....whole house is a PITA sometimes.

Anyways back to my initial question which was uhh....I'll have to look back now. Oh yeah, if I have a 14X14 grill, into a 3.5X14 duct then opening back up to say 12X16 or so, would the 3.5X14 choke this or would velocity rise to make all the same?

plumberman wrote: ↑

Sun. Dec. 10, 2017 7:22 am

you can try his idea. just pan the the floor joist out for the right size return duct. if the small restriction of the 3.5 x 14 going thru the floor proves to be to much box out into the room and make opening larger. when running flex duct up a size due to inherit flow loss. trailers are known for undersize ducts. they no how to save a penny!

So what you are saying is cut a hole in the floor and box out. Hmmmm...not sure how I would camoflauge that. Maybe a coat rack/shoe storage thingy that doubles as a CAR. That could work and be easier to change filters. Now to sell the wife.

What kind of entry door do you have in the bedroom? Would It be possible to cut a hole in the door and put cold air return vents on both sides of the door down low? The furnace spends a lot of time heating because the cold air doesn't have a path back to recirculate....Adding vents to the door will give it a path. Plus closing the bedroom vent will help as needed... Cold air will be allowed to enter the bedroom which will actually help cool it off...IMHO....This would be your easiest fix....

I like that idea, it's definitely something I would try in this situation.