Dry line or not

I am setting up a woods that has about 2% slope and will have approximately 1500 taps. I have actually 2 questions. The first is, is a dry line necessary if I over size the main lines? If I use 1 1/4 inch for the mainline instead of 1" and 1" branches off the main will this work? There will be 3 mains with the longest being about a 1000 feet with 500 total taps on that one. The others are similar but shorter. I am estimating a total of about 6000 feet of mains and branches.

The second question is do I add up all of the distances to calculate the CFM drop to the system or do I take the longest mainline distance for CFM drop. Again the will be three mainlines and about 34 lateral branches off of the main lines. Thanks for any help on this.

If 2% slope is the best you have, you would benefit from a wet/dry system.
Neil

Absolutely run a dry line. I have 1500 taps on my 1.25 over 1.25 system and several times during a good run that wet line was full and would have reduced vacuum in the woods if not for the dry line.

You need to realize, with a mainline on a 2% slope you have a very small allowance for a sag before the vacuum to the rest of the system is extremely compromised. A dry line is of great assistance in that case. If 1500 taps, I'd suggest a 1.25" wet line and a 1.5" dry line, however some would use 1" wet/1.25" dry.

I just walked part of the woods. Most of the taps are going to be closer to the lowest point. I think what makes sense now is to go with 1" mains and 1 1/4" dry line just to carry more cfm to the outer most taps. It does appear that it is more like 3% slope. The second question still is do I add up all the linear feet of main line and wet line to get the cfm loss or just the longest distance from the vacuum pump.

If it were me, I would do 1.25 wet and 1.5 dry conductor system. Why do all the work to find out you short changed your self. In the end it will pay for it's self. I hate to do things twice and its only going to be about 200.00 dollars difference.

Brian makes a great point.

I think your on the path. I run most of my setups of 1200-1500 taps on a wet dry system with 1.25 wet and dry lines with excellent results. I would look for a nice electric releaser and a 2-3 hp vacuum pump. Also Philp Widrick lives in black falls and would show you a nice setup on a wet/dry system.

Agree with most of what has been said. I will add that many times I have seen sap coming down the dry line early in the day from a frozen spot in the wet line. But you’re still getting the sap.

Well it looks like you guys are right on the sizing. The CFM at 1000 feet jumps from 8 in the 1" to 13 in the 1.25 ". That being said would you make all the wet line even the laterals off the main the 1.25"? If I go from 1.25" to 1" on the branches off the main it may reduce some cost, but if its better to keep it all the same it may make sense to do it with 1.25" mains for all of it. Any thoughts?