Sap pan is boiling over

[DougM]

I've been looking through old posts for an answer or similar situation and haven't found anything, so I'll throw this out for comments.

We have a wood-fired 30"x8' raised-flue D&G evaporator with a full-length-hood. Due to our building setup we have the stack routed out through the wall - I know, not the best. Anyway, at the end of last year we found out the elbows reduced our effective length more than we first thought, so we lengthened the vertical section to compensate, and to replace some worn-out sections.

This has increased our gph significantly, but we are consistently boiling over the back pan if we get the stack temp over about 450 degrees. I'm seeing old posts with 900-1000 degree stack temps, I think we'd float the hood off the evaporator if we got that hot. At 350-400 we have a consistent violent boil in the sap pan, but above that large bubbles start to form & it boils up into the hood.

Syrup quality & color are not an issue, we're just getting nowhere with eliminating the boiling over. Some posts I saw mentioned using defoamer every few minutes, if that's all it takes that's an easy fix, but if anyone knows another potential cause or something we need to change we're open to suggestions.

Thanks,
Doug

[Ed R]

Use defoamer. Figure out a routine with your firing schedule. Ours is every other firing. then stick with it.

[nymapleguy607]

Defoamer everytime you fire, my 2x6 takes 2-3 drops per firing and I fire every 8-10 minutes

[sugarman3]

Defoamer,and then you will want a little higher stack temp,we run850-900 on a 3x10,fire it every 3-4 minutes,add 3 drops in flue pan every fire,its all about evaporation in the flue pan,running that temp we are boiling consistantly doing 155-165 gallons per hour

[Bruce L]

defoamer every fire,then you will be able to look after other things rather than having sap roll over and waste from your back pan