When I was working on my cold air return, I tried several things before concluding the project.
After exhausting the possibilities of natural convection and fans blowing this way and that, I decided I needed a "cold air return path". My first step was to cut a hole, and place a return register into my basement, from the cold end of the house. Pictured here >>http://nepacrossroads.com/download/file ... &mode=view
The rest of that story can be seen by following the "project" links below.
This didn't work well, as the air in the basement wasn't heated, and had there been a "flow loop", the air would have lost a bunch of heat to the basement. Next, I ran a flexible 6" duct, through the basement space and back to the stove room. This worked better, but the cold end of the living space was still chilly.
Next, I built and included a "duct fan" into the return air duct. The reason I built a duct fan, was because I didn't like what was available. They were either real flimsy or very expensive, plus I had a fan. The fan I had was a two speed fan from a Broan Range Hood. http://parts.broan-nutone.com/broan/Shop?DSP=30115&PCR=1:1000&IID=413001
.. See first item #9, p/n 97011220 @ $35.46. I bent the ends of the mounting arms to 90* angle and mounted it in a piece of 8" pipe. The wire was brought through a grommet in the pipe sidewall into a small junction box, with a "single pole, double throw, center off" switch for the two speeds, with a cord from there. The 8" pipe was fitted with two 8" to 6" reducers to marry up with the flex duct. This fan runs continuously, as the coal stove makes heat "continuously".
This set-up will pretty much bring the heat to the end of the house, furthest from the stove.
Edit: Maybe I should say, "This set-up will pretty much exhaust the cold air from the far end of the house, to allow space for the warm air."
Diagram of whole heat flow. Really temperamental stove/draft !!
... Duct fan not shown.