Moving/ circulating air.

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New Member
Nov 1, 2023
Central California
Hi all, I am wanting to circulate air in our 14x42 foot house. Simple layout with heat source at front of house in living room with slightly vaulted ceiling. Kitchen/dining next with 5 foot pocket door opening, ceiling now not vaulted, then short hallway on one side of house with bathroom off of hall then hall ends with door into 12x14 bedroom.
I was planning on pulling hot air to bed through insulated duct but after much reading and searching for non existent confirmation of my brilliant idea I have succumb to the experts ideas which also makes things a lot easier.
So moving cold air, a plan this idiot would never had arrived at. So I have house in pieces and studs and small low attic accessible at present due to renovation. A tight route but can be done I think,
Question is, do I need to pull from down low and should I enter into living room high? That’s my gut feeling but I tend to be wrong often.
Also do I need a large duct area and high cfm fan or could I get away with 4 or 5” duct on a slow moving in-line fan? Route is a little tight and a bit of soffiting may be needed so minimum duct size would be good.
Thank you.
The moving cold air normally is done with fans pointed at floor. It’s easier to move cold air as it’s heavier than hot air (cold air sinks hot air rises) so let’s say you move 3 cubic feet of cold air, since it’s cold the air molecules are more dense so you’re moving let’s say 20 molecular cubic feet in that space forcing the sparse warm air into its space to keep the same volume of air in the same space.
Where it all goes wrong is moving air won’t work on a 1 way street you need a dual lane highway otherwise you will just make a cold air dam. Remember balance is essential if your intention is to distribute the heat. Think of your home as a pellet stove, you need air to create fire but push the exhaust air out the chimney to keep air to heat to fuel ratio balanced to have fire.
So you need to move air down low pushing the cold out but you need to push warm air in to fill the space. How you described your floor pan balancing vents cut high through the walls into the rooms may HELP but unless you can direct inject air into the room you’re going to have a cold air dam.
You’ll know a cold air dam when you leave a room or turn a corner and BAM you notice a significant difference in temperature. It’s the biggest obstacle trying to whole house heat with a space heater (unless the central HVAC circulation fan is used) pellet stoves are space heaters just like wood stoves or fireplaces. If they have the BTUs they will heat the entire home but never evenly.
Thank you for reply.
I should have mentioned we will have a direct vent gas fire.
I was imagining the other lane circulating the warm air would naturally occur by leaving bedroom door open. I would pull air from down low from opposite side of the room from the bedroom doorway.
My wife is not so happy with the box fan or doorway fans so I was hoping to achieve cold air circulation via hidden duct.
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Ok my bad may not have seen which heating system you was using. However moving air is same principle. You can use upper “jump ducts” or “balancing vents”. Which is basically cutting a hole through the wall above the doors then sealing the space from the interior cavity and finish installation with a vent grate on each side. This allows the warm air to circulate.
If you ever tried to close a door but it phantom swings back open? That’s compressing to much air in a space but if you crack a window open and the door closes fast it’s the air compression is forced out the window creating a vacuum effect. A hole pass through the wall allows the compressed air an escape out of room above door way. Same principle for air circulation and balancing