Hello all,

We are in the process of installing a new standalone hot oil unit. The expansion tank is a vented design and there is an automatic air vent in the system that will be used to vent any air upon first fill up into the expansion tank. I was told by the vendor that we also need to install automatic air vents on the process piping, we can do that, but not on the highest point of piping. We intend to install one on the supply line and another on the return line.

My question is:
1. Will we get an airlock in the piping between the supply line automatic air vent valve and the return line automatic air vent valve. It is roughly 15 - 20 ft. of 1/2" piping & hosing, it goes up and down multiple times with the highest point being ~ 30 inches higher than the automatic air vents
2. is there any issue with using automatic air vents ?
3. Will we still need to install some sort of vent on the highest point of piping in the process side ?

Thanks