Gravity feed, to vent or not to vent...that is the question

[Clinkis]

I know this question has been discussed on many posts already.....but it's cold and snowing and I have nothing else to do so i would like to revisit this topic.

I have 2 small pipe lines with with approx 25 taps each on gravity. They are constructed entirely with 5/16 tubing. They work ok but never seem to yield what they should. When I purchased the supplies the guy there told me to vent them at the high points. I've read on here that there should be no vents on gravity....so which is right and why?

[ryebrye]

I know this question has been discussed on many posts already.....but it's cold and snowing and I have nothing else to do so i would like to revisit this topic.

I have 2 small pipe lines with with approx 25 taps each on gravity. They are constructed entirely with 5/16 tubing. They work ok but never seem to yield what they should. When I purchased the supplies the guy there told me to vent them at the high points. I've read on here that there should be no vents on gravity....so which is right and why?

The prevailing wisdom is don't vent. It allows bacteria and fungus in that will cause the tap holes to close sooner. It also causes any natural vacuum to go away.

The guy selling you the equipment may not be the best informed.

[maplefarmer]

I ran a line along a driveway with 24 taps 12 going each way with a 210 gal tank in the middle, have a tee threaded into the cap of the tank and last season I got a lot of sap from that setup, in fact the last taps on each end are almost going uphill, but it seems the vac. would pull the sap along. set it up this year, but so far we haven't had a run.

[Rselleck91]

I had run into a incident this last season with a vacuum pump going down. I let everything run on gravity I was getting quite frustrated with less sap out of the bush I decided to investigate. My lateral lines that were over 50' long or so with at least 4-5' of drop the sap would flow good into the mainline. Now my lines that had maybe 20' or less of branch line with a foot or two of drop would hydro lock. Sap would not make it to the mainline. I found the saps weight would not overcome natural vac. Longer lines with a little more drop but using same pitch the weight would pull the sap using the 5/16. I guese the moral of the story follow leaders tapping guides close as possible that they put out in there catalogs