Help needed Barrel Gaps

I used a 40gal WH tank to cover and insulate the heat riser (16"W)with a 55 gal drum 22.25"W with a 3" gap(c) on top that leaves little over 3" gap(g) along the sides is this going to be a problem ? TIA Azdave

David Marin : With the wider gaps you MAY get a little less heat energy scrubbed off by your exhaust gases against the sides of your barrel, and a little more
heat transported to your Thermal Mass, this is hard to measure and should not be a problem, just an observation !

Make sure that the Transitional Area is very generous and pretty smooth -where the Vertically falling gases turn at right angles to flow horizontally through your
Thermal Mass .

A very simple rule, as soon as the barrel goes on, the vertical chimney MUST go up (4-5 feet about the highest peak/obstacle in your area, and never inside !)
Check your clean outs with a candle or a lit incense stick, there should be No movement of flame or smoke towards the clean outs ! Hope this helps and is timely !
Big AL