Moving air around??

[Bone1099]

I have been strugling to heat with a fisher insert for about 5 years now and im just tired of runnung blowers and fans and ceiling fans just to stay kinda warm in the bedroom, My house is roughly 1500 sq ft and insulated about average but it is just hard to heat the far end of the house. I am confident that my stove is capable of heating this area and most of my problem is a crappy floorplan for my stove installation. The most success i have had has been this year. I finally broke down and bought a box fan to sit in the hallway and blow the cold air from the bedroms to the kitchen/dining room where the stove is. Then I use a makeshift blower in front of the stove(blue blower) and a ceiling fan to further stir things up. and all this just pisses me off thinking that by the time i run all that extra crap I coud just run the electric heat. So what im thinking of doing next is installing a decorative register in the ceiling in the dining room above the stove. Then an insulated duct all the way to the end of the house split into two smaller registers in the bedroom ceilings with some kind of inline blower or squirrel cage fan to move the warm air from the area above the stove to the bedrooms and also allow the same amount of cool air from the bedrooms to return to the dining room via the hallway creating a nice circulation path. Then only run this duct fan and not all the other gadgets i have piled up. But im sure there is some unforseen pitfall to this theory so if anyone has tried anything similar or just has any pertinent advice please feel free

 

[Renovation]

Hey Bone,

You're heading in the right direction, but should pump cold air, not warm.

Instead, put floor-level inlets at the far ends of your bedrooms, and run a insulated, powered duct to an outlet near your stove (I'd say behind, if it weren't an insert, but you can put it as close as you want, as long as you heed the combustibles clearance). Make sure the warm air that will take its place can get into your bedrooms--under the doors, etc. Also, use ducting that's smooth on the inside, usually metal and definitely not the plastic-over-coiled-wire kind. The POCW is rough inside, and will severely reduce air flow. Use ducting that's smooth inside and insulate it.

BTW, fans don't cost a lot to run, especially at low speeds. They're worth it, IMO.

HTH, and good luck! Please come back and tell us how it comes out.

 

[soupy1957]

Time for a stand-alone wood stove.

-Soupy1957

 

[woodgeek]

Moving heat is about volume of air. A box fan in a hallway will move a lot more air, and do it with a lot less electricity than a duct/inline fan. I hear ya on the not having fans all over the living space, but in the end, the elec on the fans is not likely to be a big issue. Bigger fans moving slower are more eff at moving air (CFM/watt). So ceiling fans are the highest, inline blowers the lowest eff.

FYI, the formula for moving heat is: Heat(BTU/hr) = 1.08 * CFM * Delta_T(°F).

So if you want to move 10000 BTU/h to heat the far end of your house, and the Delta_T is 20°F (i.e. stove room is +20°F from far end of house), you need to move 460 CFM. If you want to be more even, 10°F, then you need to move 900 CFM. A box fan can move that volume of air down a hallway easily. A duct/blower can too, but it will not be a little 4" duct/fan. If you turn all the fans off, and the far end of your house is getting some heat, the natural convection is likely already hundreds of cfm, the same formula applies.

As many have said, moving the cold air to the stove works well, the warm return flow is through the living space.

 

[vixster]

Woodgeek, nice explanation. So this part confuses me, if the main floor is toasty, ( with a fan blowing towards living room where stove is) but the second floor needs warmth , at the top of the stairs do you put a fan blowing downstairs? And is there a difference between a box fan or the window fans that actually have two fans in them, side by side.

 

[vixster]

Woodgeek, nice explanation. So this part confuses me, if the main floor is toasty, ( with a fan blowing towards living room where stove is) but the second floor needs warmth , at the top of the stairs do you put a fan blowing downstairs? And is there a difference between a box fan or the window fans that actually have two fans in them, side by side.

 

[Renovation]

Woodgeek, nice explanation. So this part confuses me, if the main floor is toasty, ( with a fan blowing towards living room where stove is) but the second floor needs warmth , at the top of the stairs do you put a fan blowing downstairs? And is there a difference between a box fan or the window fans that actually have two fans in them, side by side.

+1 on Woodgeek's explanation

I believe the answer to your first question is yes, to blow cold air downstairs. Others with experience can verify.

Regarding fan differences, yes. All else equal, the larger diameter a fan, the more air it moves with less energy, and the slower a fan turns the quieter and more efficient it is. This is why blower fans are so noisy, and ceiling fans so quiet. So a big, slow-moving fan is the most efficient way to move air--more efficient than multiple small ones.