fan for moving my hot air

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ramdez

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Dec 29, 2009
51
eastern PA
Hello all, I have a bi-level and have my stove in the finished basement corner and it heats my whole house fine in Eastern PA. I would like to grab some more of the downstairs heat and get it upstairs rather than thru the stairs in the middle of the house. I was thinking vents, then powered vents, now I'm onto high CFM squirrel fans or in duct fans. The theory is that instead of putting 3 or 4 vents in the floors and dealing with those issues i would just put 1 fan in and run a duct down along my center I beam in the house and pop it up every 15 feet or so.

Any experiences with this?
 
so add more cold air returns? my stair way is the main way the air moves now. the steps are so cold and drafty i can't even sit on them so i thought i had enough cold air return. i wanted to move and distribute more hot air upstairs. if i add more cold air returns, can the hot air move up stairs more and distribute itself ?
 
cool thx. i see tons of stuff for moving air, can i apply a similar principle do adding a cold air return? or should i just put fans on the floors of my second story and pull the cold air across? would that be better than adding cold air returns in the floors?
 
Cold air fans work better than hot air fans. %-P

Joking aside - cold air is more dense than hot air. Makes it easier to move. Hot air being lighter has an easier job of moving around to replace the very small negative pressure that is created when you remove the cold air from an area.
 
so how can i add more cold air returns or move my cold air better then? my stair way is in the center of the house and actually moves a ton of cold air. i can't even sit between the stairs and the pellet stove most of the time. how else can i move the cold air then? put vents, a duct, and fans at each vent to push the air?
 
ramdez said:
so how can i add more cold air returns or move my cold air better then? my stair way is in the center of the house and actually moves a ton of cold air. i can't even sit between the stairs and the pellet stove most of the time. how else can i move the cold air then? put vents, a duct, and fans at each vent to push the air?
Click to expand...

Unfortunately - that is one of the downsides to a basement install. There is typically only one way in and the same way out. Your stairwell is acting as a duct for both cold and hot air. In the old days, floor vents were used. Usually they tried to strategically place them to allow for a thermal loop. Ducting the cold air down may give you the most bang for your buck.

All that mumbo-jumbo said - be aware that air ducts are not allowed within a limited distance of your stove for safety reasons (fire can travel from one area to another, very fast) so you may want to try and think of the basement as the heat source, not the stove itself (if that helps with anything). I know I am being somewhat vague, but it is impossible for me to armchair design a "system" with what I currently know of your setup. Not to mention that I am not a "designer" of this stuff to begin with. :) Just trying to throw some "thought" out at ya.
 
Is it possible to use your furnace fan and draw the basement hot air thru the furnace and duct work? Basically the furnace would suck the warm air in the basement and pump it through the whole house.
 
Jamess67 said:
Is it possible to use your furnace fan and draw the basement hot air thru the furnace and duct work? Basically the furnace would suck the warm air in the basement and pump it through the whole house.
Click to expand...
Im a duct guy by trade. you would have to have hood of some sort right over the stove for it to work. just having it sucking through the returns wont do much. your duct would need to be super insulated to keep the air warm. but most likely it'll cool down to much to make a difference
 
I appreciate all the replies. I'm currently using a harman p61a to heat my 1900sqft bi level and it was previously electric baseboards which i don't use. i couldn't put a stove on each floor and opted to try one in the finished basement and not use the electric upstairs. it's working fine. i can keep it at 75 downstairs and 70 upstairs unless it gets in the single digits outside then it gets closer to 80 to keep it at 70 upstairs. it's not a problem but i was wanting to make sure i was using all of the heat i could.

maybe i'll start with trying to make more cold air returns some how and see how that goes thanks for the help everyone.
 
I know everyone just says, move the cold to the warm but that is not necessary in many cases. I think you have to go with how the air in your house circulates naturally. I have a split level with the stove down stairs too. The heat naturally rises along the top of the stair well. The cold air flows down stairs along the base of the stairs. The natural flow with the stove in operation is very apparent. I DON'T have any issues with the cooler air getting back downstairs so I opted to boost the flow of warm air upstairs with a corner door fan. The fan is always on but it is apparent when one of the kids or the wife knock the plug out - it gets hot down there. I am in the process of running some ducting and an inline fan to move more air - about three times as much as I have now. I don't expect this to heat the entire upstairs but it will contribute to heating the upstairs. The ducting is through living space walls and not through an attic or basement that is cooler than the rooms.
 
I have to agree with the above. I would try to keep the natural occuring currents in the house flowing as well as possible. It was stated earilier that cold air is easier to move than hot air. In my experience, this is completely false. Cold air is in fact more dense than hot air, meaning it has more molecules in x volume. As air is heated, the molecules spread out creating a greater volume of air. Gravity will have more pull on cold dense air than on hot, less dense air.

It takes more energy to move dense air. It the reason that in a house with heat and A/C, the furnace should have a multi-speed blower. The fan should be set on high during a call for cooling, otherwise, if the cold air is moved through the duct too slowly, it will create a tumbling effect inside the duct and will not properly cool the house. In turn, the fan is set to run on low during a call for heat cycle.

It it were me, I wouldn't add any ductwork at all, just give the hot air and easier passage to the upstairs. Such as floor registers that open to the basement ceiling. (assuming your basement has an open floor plan)
 
mrfjsf said:
It was stated earilier that cold air is easier to move than hot air. In my experience, this is completely false.
Click to expand...

You are not differentiating between natural convection and forced (unnatural). When using force (fan), the blades will actually move MORE air if it is dense. It has "more" to get a hold on.

Think of the prop on a boat. The boat would not move nearly as well if the prop is cavitating. The reason for this is water density. Not as much water (air mixed in, less dense)- not as much propulsion.

Air works in the same manor as fluid dynamics.
 
Jags said:
mrfjsf said:
It was stated earilier that cold air is easier to move than hot air. In my experience, this is completely false.
Click to expand...

You are not differentiating between natural convection and forced (unnatural). When using force (fan), the blades will actually move MORE air if it is dense. It has "more" to get a hold on.

Think of the prop on a boat. The boat would not move nearly as well if the prop is cavitating. The reason for this is water density. Not as much water (air mixed in, less dense)- not as much propulsion.

Air works in the same manor as fluid dynamics.
Click to expand...

I didnt recommend a fan to move any air at all. The floor vents I was suggesting would be convection, not forced.

I understand where you are coming from, but by your logic, you are suggesting that it takes less energy to move dense air in a forced air system at the same velocity as it does less dense air. Im sorry but it just isnt true...

Air that is more dense is heavier than air that is less dense. Thus requiring more energy to move the same volume of air at the same velocity.

Not trying to argue physics here, im just pointing out basic pyschrometrics.

Or, am I misunderstanding you?
 
mrfjsf said:
I understand where you are coming from, but by your logic, you are suggesting that it takes less energy...
Click to expand...

Not trying to beat a dead horse, cuz we were discussing different approaches for the OP, but...No, I in no way was talking about energy consumption to move air. I was referring to a fixed speed fan (or prop, in the case of the boat example). At a fixed speed, the fan will have more "force" on dense air, than on less dense air.
 
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