Will a hood vent increase rate of evaporation? I'm boiling down some maple sap this year on the stove top.  A bit late but thought I'd give it a whirl even if it only yields a quart or two of maple syrup.

Will keeping the hood vent on increase the rate of evaporation?

Conventional logic makes me think yes, but I just read a few threads on this topic and left feeling a bit confused since some people indicate that the hood reduces the surface temp and creates an inconsistent boil which can decrease the rate of evaporation.

EDIT:
Since there has been some discussion below in regards to the type of hood vent being used so I'll add this: It's a fairly standard residential hood vent that vents to the outside through the ceiling (not the recirculating kind).  When it's on it is definitely pulling steam out of the kitchen — I can see the steam flowing up through the vent.

Also, the pot is on at a simmer. The amount of steam being produced here is not a large quantity and the hood seems to do an adequate job of removing all of it. For purposes of answering this question, please assume that the vent is removing steam.  The question in this case is, will removing steam at the rate which it is produced increase the rate of evaporation.
I'm boiling down some maple sap this year on the stove top. A bit late but thought I'd give it a whirl even if it only yields a quart or two of maple syrup.


It takes between 20 to 60 quarts of sap to make 1 quart of maple syrup.


  Will keeping the hood vent on increase the rate of evaporation?


You'll want to do it outside, too much steam; sap is mostly water. If you are insistent on doing on the stove top then keep the hood fan on, enjoy the smell, and be prepared for flies and bees to have an inexplicable attraction to all the surfaces near your stove.

Your kitchen stove's hood fan is too far away to affect the boiling, or capture all the sticky steam. 20 quarts is 5 gallons, and 60 is 15. A 6 gallon pot is approximately a foot diameter and a foot high. Providing those measurements in metric won't make it seem any easier. :)


  Conventional logic makes me think yes, but I just read a few threads on this topic and left feeling a bit confused since some people indicate that the hood reduces the surface temp and creates an inconsistent boil which can decrease the rate of evaporation.


Venting is necessary, even outside it's desirable, just to get rid of the steam. In your case you'll want to vent, and there'll be no effect on the temperature. Professionals vent, those that don't say that the next thing they are doing is inquiring about getting some vents.

Check out these two threads, it's all steam; everything will be soaked.