a couple of items to have with you vac setup.

[knight_toolworks]

lessons learnered here. a vacuum check valve is a good idea when using the smaller motors. You set it so when your system is closed it will let air in and drop it about 1/2" or so that way it keeps your motors from overheating.
http://www.mcmaster.com/#vacuum-relief-valves/=grni1s
item number 48935K45 (http://www.mcmaster.com/#48935K45) you want the 3/4" one to let enough air in. these are dirt easy to add to a system.I just use a 3/4" female pcv pipe fitting I made a flange it fits snugly in out of sintra glue it in with pvc cement drill a hole where you want it and screw it in place with some silicone. I have two vac boxes one pulls more " then the other. with these valves I can run both of them at the same time if I need the airflow and my motors are fine. otherwise the weaker motors can overheat from lack of airflow.

Brady told me about this type of check valve. Check valves are great if you want to run or need to run motors separately or if you have two vac boxes and need to switch between them. this clear one is handy to make sure it is working and it costs less only 10.00 on amazon.
http://www.amazon.com/gp/product/B001OE1AB4/ref=oh_o00_s00_i00_details
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/79a56d1c.jpg

[michael_schwartz]

I wish I had found the clear check valves at that price.

The 2" swing check valves I bought were about $20.00 each and they work with the slightest bit of air pressure.

The relief valve does seem to work well. I paid a bit more from mine, but I was able to pick it up locally (80 mile round trip) at grainger.

[knight_toolworks]

I wanted to change them in case it was part of the problem. but it is nice to be able to see and they cost less then the normal ones. I don't think there is enough spring pressure to make much of a difference.
I needed two valves after thinking about it so I bought the first from Granger the second from mcmaster. They are exactly the same but granger is faster at shipping now. sometimes they drop stuff off at my shop the next day.
here is the fast way to attach it.
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/df52d4e1.jpg

[michael_schwartz]

That is good to know they both are the same. I figured they would be, but you never know. Mcmaster does ship here in about 2 days. The way I plumbed the valve was a bit on the complicated side, but I wanted to restrict the maximum potential airflow, and I didn't have time to find a more elegant solution.

At that price I may buy a set of the clear check valves just to see them working. It would also be nice to confirm my theory as to how they should work.

My motors are wired up, and running, and I have the plumbing minimized to 2.5 elbows to get to any one zone. I just need to finish up my spoil board, and finish the installation of my plumbing.

[knight_toolworks]

I put mine on a t on the main line only to realize that I have two vac boxes and they both pull a different amount of " so I had to add the second one before the first.

[gene]

Why do you need check valves on your vac system? are you drawing a vac then turning off the vac , i dont understand the mechanical benefits of this? :confused:

[knight_toolworks]

Why do you need check valves on your vac system? are you drawing a vac then turning off the vac , i dont understand the mechanical benefits of this? :confused:

myself I have two vac boxes so with the check valves I can have them both connected and the check valves shut one off when not in use.

[michael_schwartz]

I have two motors so I am using check valves on each so I can run one, or both, depending on the situation. The valve prevents one motor from sucking through the other.

This also has some benefits in case one motor fails, blows a fuse, or a breaker trips, etc, since the other is then completely redundant, and wired on another circuit.