Difference in surface temp between single wall and double wall pipe?

[Nonprophet]

In an effort to get our new Oslo to burn better, I've re-done our chimney. I was using single wall pipe from the stove to the wall thimble, but in scoring some used 6" class A stove pipe I got a couple pieces of basic double wall for inside use. So my question is, what's the difference in surface temps between the two as measured by a magnetic thermometer?

With the single wall pipe I was always shooting for about a 300 degree temp 12" or so up the pipe, but what temps should I be shooting for with the double wall? Logic tells me 1/2 (i.e. 150-200 degrees should be good) but then again the clearances go from 18" with single wall to 1/3 of that (6") with double wall--so 1/3 the surface temp i.e. 100 degrees?? FWIW with between a 450-500 degree stove top temp, the double wall pipe is running about 180-200 degrees.

Thanks!


NP

 

[devinsdad]

I'm afraid that a magnetic thermometer is just about useless on double wall pipe. To get a flue temp. on double wall you would need a probe type thermometer but their accuracy has been debated not too long ago. I have one for my double wall but don't really go by its reading as it reaches 1000 °F before my stove even reaches 450. I kinda use the magnetic thermometer on my stove top but when comparing 2 of them side by side they differ anywhere from the same to 125 degrees off . Hope that helps