Due to the recent electricity price hikes, I have been putting my home made woodburner on about 7pm after coming back from work, rather than having the "off peak" on. Last night we had a gale but a warm one, so it got about 8pm before I fired it up. Instantly I got a roar like a blast furnace. I thought this is going to throw out a lot of heat, but it didn't. I made a "spinner" Christmas decoration, and put it on the mantlepiece last year, found it gives a fairly good indication of how much heat is coming out of the fire, so have left it there since then. Last night it didn't spin for the first half hour and the door of the woodburner hadn't got too hot to touch either. Wood was burning hard, and a roar usually indicates it is getting hot. So was the wind simply sucking all the heat up the chimney?