Cleaning bottom of sap pan, it is necessary?

[ennismaple]

When, at the end of the season, I remove the sap pan for cleaning the soot build up is 1mm or 2mm at most. Would I be losing much heat transfer through that little soot? My stack temperature is around 1000 degrees F so it is burning pretty hot under the flues.

If your stack temp is 1000F you're losing a LOT of BTU's up the stack. I've never done the math but a couple mm of soot will significantly inhibit heat transfer into the pan. We've been working to optimize our primary and secondary air flow rates and how much wood we use in each fire to keep our stack temps to 600F. We've found that the difference in boil rate is nominal with significant reductions in wood burned, plus we're less likely to get scorched nitre in a long boil.

[Swingpure]

We've been working to optimize our primary and secondary air flow rates and how much wood we use in each fire to keep our stack temps to 600F.

What do you use to measure your stack temperature and how high up from the evaporator do you measure it?

Thanks

[randomseeker]

I use a SmokyLake digital control unit that has a probe for the stack, which I measure about 4 feet off the bottom of the stack.

[randomseeker]

That's interesting. At 900 to 1000 degrees I get the highest boil off rate. 600 is the bottom of the range at which any boil off happens. It doesn't take any more wood per stoke to go from 600 to 1000, it depends upon the bed beneath the feed. If I can get the coals really hot I get the higher temperature. I don't have good data to show much much boil off I get comparing temperatures. This is very interesting. I will have to do some reading on this.