Making Maple Syrup Production Discovery

by Tig Tillinghast

I don’t think I’ve seen this in the maple syrup literature, so I figured I’d just put it out there to see if others have noticed this vacuum effect.

(Friend's) Vacuum Extractor

(Friend's) Vacuum Extractor


We found that we were losing vacuum on our mainlines in our major bush. This happened steadily over a period of about a week in the middle of the maple syrup season. That’s not so unusual. It could be squirrels or any number of things happening to loosen lines and create vacuum leaks. But then it rained, and our vacuum maxed out without us doing any line repair at all.

After this, we started observing the vacuum levels relative to the precipitation and found that after three or four days without moisture, our vacuum level started a similar decline. Perhaps 5 percent per day. In every instance, a rain event of more than a few minutes brought us back up to normal.

We concluded that our tap holes were shrinking away from the spiles during the dry periods. This sounds like a pretty simple explanation, but I hadn’t heard others making mention of it. If true, I’ve wasted a lot of line fixing time running around trying to tighten a system whose trees were merely parched. It may also be that this is peculiar to the type of spile used (Lapierre). Would be curious if other maple syrup makers have noticed anything similar.