Electric Company Couldn't figure it out!
Back in the late 70's I purchased a 2-barrel kit from SOTZ,I set it up in my basement in Indiana, it was a L-shaped Ranch. I dropped down my forced air heating vents and vented out my chimney to the fire place vent above.
The first month of using it, my gas bill dropped about $200., it went down to $19.16.
They came out in the middle of the month and changed the gas meter, the next month it was about the same, around $20.00. The gas man came to my door when they read the meter again and asked me"What the Hell are you using to heat this house"?
When I showed him he said he was going to get one himself.
I also had a 30-gal in my garage.
I was more than satisfied with the product.