Laugh all you want. I dropped my natural gas bill from $200 to $20 last year. Doesn't totally eliminate, but did drop it majorly. I am heating an 1800 sq ft 2 story with it. Cheaper than putting in a wood burner, chimney, etc, and way cheaper than a 100% outdoor whole house unit. In regards to the cfm, I am going to do some experimenting this winter. My uncle is in the htg/ac business for about 30 yrs. Suggested a larger than 8" return. Didn't think you could physically push that much cfm with only an 8" return. I will keep you informed.
laynes69- Do you own one or is this an opinion with nothing to base it on?
ericjeeper- Not the prettiest, but neither is a metal outhouse in your backyard.
AOD- Based on my uncle's math you are right, it is about half the rated output
All I know is if you have a smaller ranch, modular, house trailer, or smaller house they are a great alternative. It won't heat a mega-house or old farmhouse that has been added onto 6 times very well, but it does pretty good in certain applications. I refer to something like this as "a honey for the money"! Will have paid for itself by the end of the winter. I would be looking at 5 more years to have paid for a true whole house OWB plus last year. 6 year return on investment was too long to wait for me. I didn't get mine installed until mid-January last year. Roughly 1.5 year return.