Where do I measure stack temps?

[MrEd]

I've mounted by probe thermometer about 30 inches above the "T" that comes out the back of my Tarm. Can't remember now why I put it so high(I swear I read it somewhere)...

Where is the best place to put it? My stack temps seem low, but maybe because I am measuring too far up?

 

[chuck172]

The directions I got from Tarm say mount it just down stream of the boiler flue collar.
I believe lower stack temps mean that the heat is efficiently heating the water chamber and not wasted up the flue. As long as you are in gasification.

 

[Nofossil]

You're probably not losing much flue temp in 30 inches. Make sure that the probe is near the top side of the pipe. At low flow velocities, there can be quite a temperature difference in different parts of the flue cross-section.