BOOH VI

[Nutcase]

Matt, I am generally giving barrel top temps, not face temps. I've never maxed out at even 12" from top dead center.

I think that from a utility perspective, face temp is probably more relevant than tdc temp, as this better assays the total heat released by the system, a function of both exhaust temp and volume. I mean, you could run a propane torch under the barrel at tdc and max out the thermometer, but it wouldn't actually heat the house, would it? I've been focusing on tdc temp to date because I wanted to know how the heart of the system was behaving. Scaling it to heat the house is another thing. There are only so many BTUs to extract from a pound of wood.

I think with BOOH VII I've got something sufficiently robust and stable to make tracking and comparing face temp more center stage. Where do you like to measure? There's a strong vertical gradient, so comparisons require a point of reference. Even there, we have complications, as my system has a comparatively skinny riser and therefore slower flow down outside the riser and therefore more of a temp gradient, even with a similar burn rate.

Anyway, I will start reporting face temps with the thermometer placed just above the top ring, 10" more or less from the top of the barrel, or wherever you suggest.

[matt walker]

The largest issue I have with top temps as a guide is that it is often above what the average cheapo flue thermometer can handle. I demagnetized my first one by trying to measure up there, and as you found out, all too often your measurement ends up being "off the scale."

I like to measure the hottest part of the face, which is a function of riser placement, both vertical and horizontally within the barrel, and, as you noted, barrel side gap. If you have an IR gun, you can find the hot spot. For me, it's typically about 4" down from the upper rim, and while one side of the barrel is slightly hotter than the other, I just put it where I can most easily see it.

A hot run for an average indoor burn on my system is from 500°F up to about 600°F, although at the high end there is where I typically draw the line. Average is right around 400°F-450°F.

[Nutcase]

Okay, I will go to 4" down. Because the cheapo thermometer is so slow to respond, it's hard to find a max, so I will just go with that for now.