So I bought a 4100i and somehow after all the questions and research I had an understanding that the controls were integrated into the unit. To my disappointment I find it was not come installation day, all this after I had spent the time to get power into the old firebox. But a solution was quickly formulated. Homemade rheostat integrated into the thin sheet surround panel. No cutting or rewiring on the factory components either! Basically I took a rheostat and wired it to a standard outlet and joined the boxes back to back and plugged it all in. Put into the location where the factory cold comes out so if it is not too hot for the cord there it shouldnt be for this either. I'll have to keep and eye on it even though I covered it in high temp insulation. Paint a couple stainless screws and...now to clean up the overspray! I thought I had it covered. Oh well.