High and Low Pressure

[Brad W Wi]

Is there a connection between low and high air pressure (weather) and sap running? I noticed this year when I had low pressure areas moving in I got good runs of sap. And when high pressure areas the sap collected was noticably lower.

[ennismaple]

You've got it exactly. Sap runs because of the pressure differential between the interior of the tree and the atmospheric pressure. When a low pressure weather system moves in the diffential increases and the sap runs more.

Vacuum systems basically do the same thing - they increase the differential which makes the sap run more on marginal days.

[Mike]

Ennis, Nice set up you have......Haw many taps do you have?? Mike

[mapleman3]

Not only that but you will also get a better boil off rate on low pressure days also due to the lower boiling temp on a real low pressure day syrup may come only at 217deg...sometimes on a high pressure day can go 220deg or more

I like the low pressure drizzle or snow days for sap :)

[ennismaple]

Thanks Mike. I think we're at something just short of 4000 taps, with all but 200 on vacuum. We've added another 500 or so on 4-seasons line and the 19/64 health spiles over the last two years. We've got plans for another 2000+ taps in a new bush that we've been thinning since the '98 ice storm. All we need is more time and more money!