Percentage of sap increase from 1" to 15" vacuum

[Starting Small]

I have heard you can expect 5%-7% sap increase for every inch of vacuum over 15", but how much percentage increase for the first 15? I am running 20" so just trying to determine how much that would be over gravity. Thanks!
-Dave

[mellondome]

I believe that 15 will double gravity.

[Starting Small]

I appreciate the reply, it wil help me to determine storage space and how much i should expect to tap this year. thanks again,
-Dave

[blissville maples]

would expect about double, but depends on trees

[ennismaple]

Depends on your woods too. One section of woods we used to tap with gravity was a terrible producer because it was very flat. When we went to vacuum it more than doubled production - even at 18" Hg. Other sections of woods that have more slope resulted in less increase when we went to vacuum.

Get a tank that's as big as your pocketbook will allow! I can't say we've ever complained a tank was too big. You will find a way to fill it.

[BreezyHill]

I have heard you can expect 5%-7% sap increase for every inch of vacuum over 15", but how much percentage increase for the first 15? I am running 20" so just trying to determine how much that would be over gravity. Thanks!
-Dave

The data from UVM or Cornell, not sure witch it was, is 151% from gravity to 15".