Our house has 1850 square feet on one floor divided into one living room/dining room space and two bedrooms.

The house is heated primarily by a wood stove and secondarily by electric baseboard heaters. Because of limited air circulation, we use the baseboard heaters in the bedrooms a lot more than we'd like, so I would like to increase the circulation of the stove heat so we don't have to use the baseboard heaters so much.

The stove is located centrally in the main space, and the cold air intake for the stove consists of a pipe from the unheated basement to the air intake on the stove to increase efficiency and provide some positive pressure upstairs. Both bedrooms have cold air registers venting directly to the basement (no duct work.)

I've been looking at booster fans to replace the cold air vent grills, but from the descriptions, I can't tell if they blow air into the room or from the room.

Seems to me that a register booster fan blowing into the basement would help circulation of the upstairs heat, but I'd like to know, first, if my thinking is right on this, and second, if such booster fans can either be purchased (and where I'd fine them) or configured to blow to the basement, not from it.

Thanks for your help.

B.

Not sure I have the set-up clear but here goes. I assume the pipe from the unheated basement to the stove intake is for combustion air. While that may provide some positive pressure to the main room, it is more likely that it causes negative pressure in the basement. That negative is balanced by warm conditioned air flowing to the basement via the bedroom transfer vents. In effect, taking warm air from the main floor and trying to heat the basement.

Before I did anything else, I would close and insulate the bedroom registers to the basement. Keep that warm air where you want it. I would also leave the bedroom doors open as much as possible. You might also try a ceiling fan to get some circulation. Have it turning so that warm air is drawn up, pushed against the ceiling and back down the walls. You reverse that flow in summer. Other than getting combustion air, I see no reason to connect the unheated basement to the conditioned space.

Leave the bedroom doors open and use box fans to move lots of air (thousands of CFM) out the lower half of the bedroom doorways. Small amounts of air through ducts won't do it (unless you can pull very hot air from just above the stove).

Your setup is unclear, but combustion air for a sealed stove needs to come from the outside. Period.

Some stoves are capable of drawing the air heated (not burned) from an alternate source. If that's what you are doing, it might be worth it to put a small booster fan on the duct going from the basement to the wood stove. Keep the bedroom registers open to allow cooler air at the floor to return below. This is the most natural setup. You want to go with nature, not work against it.

I have a very large wood fireplace and the volume of warm air that blows out of the plenum is remarkably small. It's warm, but it doesn't come out very fast. Using a small booster fan on your duct will save expense and energy.

What you might want to do is look into converting the stove into a mass heater, a-la rocket stove.

The specific heat of air by volume is very low, about 0.018 BTU per degree-F per cubic foot. So unless the air you're moving is a LOT hotter than the room you're heating, it's going to take a gia-normous amount of cubic feet per minute. eg:

Say the bedroom has a design heat load of 1800 BTU/hr, and the air 65F when heating the place to 70F. If the air in room supplying the air has an air temp of 75F, that's a 10F difference from the air you're removing near the floor.

1800 BTU/hr (/60 minutes/hr) = 30 BTU/minute At 0.018 BTU per cubic foot per degree-F and a difference of 10F each cubic foot moves 0.18 BTU. So to supply that 30 BTU/minute needs an air flow of 30/0.18= 165 cubic feet per minute of 75F air to enter the room, as 165 cfm of 65F air is leaving the room. A typical hot air furnace register delivers about a third that much air, give or take , at a much bigger temperature difference. If the source air room is only 72F it's only a 7F difference, and ~240 cfm.

jonr's recommended box fan blowing down the hall can move enough air to even up the room to room temperature differences if the doors are left open, but there's still the wind chill to consider. The goal is to make it more comfortable for the humans, not to match some number on a thermometer.

Combustion air volumes for air tight wood stoves are pretty tiny, usually under 10cfm even at full fire. Even if the house is pretty tight it doesn't absolutely REQUIRE ducting outdoor air directly to the firebox, but it doesn't hurt. Most houses will leak more than 10cfm at pressures much smaller than stack effect of a hot flue, but you're not really gaining anything by drawing it from the basement- the sub-10cfm of combustion air is still leaking into the house from some random location. If ducted directly to the outdoors the path is known, but more importantly, in the event of backdrafting from wind pressures etc, the backdraft path is also known, and isn't mixing with your conditioned space air. Wood stove door seals aren't super-tight and will still leak some combustion products into the house in a backdrafting situation, but they're still a lot higher impedance than a 3" metal flex duct directly to the outdoors, and most of the backdraft goes directly outside.

I'm not really sure BTU even have to enter into this. Any heat you push into the unheated basement is going to be...better. You already have the warmed air, all it has to do is move or circulate between the upper and lower floors. A basic blower with 160 cfm would fully move the air in a medium sized basement "living room" in 15 minutes. 4 changes per hour. It's just a bit quicker (and more comfortable) to suck it directly out of the basement, past the heat box and into the living area, where it presumably gets pushed out into the bedrooms.

Here is a website that discusses heat distribution from a radiant stove. http://woodheat.org/move-heat-around.html Not sure what your attic looks like, but relatively modest inline fans and ductwork can move radiant heat to distant rooms. I have two fans in a chimney chase at about 350 cfm combined that move heat reasonably effectively through six inch ducts. Trouble is, it takes at least 85 degree air to make a difference -- I start the fans with a snap-disk thermostat -- and my bedrooms are upstairs so there is a natural return down an open stairwell. You might measure the temperature at ceiling level near the stove to get an idea of temperature difference. You'll see cautions in the website above about pulling air from directly above the stove. It can be done in controlled situations like my chase, by pressurizing it with a slightly more powerful fan blowing in than the one pulling heat out, but you for sure don't want to create a negative pressure on the stove or stovepipe.

Your basement approach isn't going to work in a cold climate if it's unheated and uninsulated. Fans would chill your bedrooms until the stove warmed the basement mass to a meaningful temperature difference. At the moment, air is moving through your registers INTO the basement as makeup for the stove and accomplishing some air movement upstairs. Even there it's best to use outside air supply to avoid depressurizing the house and drawing in outside air where you don't want it.

Overall, there are no good answers in a single story house. Have you considered a minisplit heat pump?