I have 5 racks with this type of system . I am not sure how to figure out what version of enviroguard it is and nor do i fully understand the concept tyler is implimenting.Here goes , drop leg comes down condensor tees off to an oldr going to the receiver and a solinoid in the liquid line going out to the cases. I see no subcooler in the systems. Also , there is a pressure regulator at the receiver, No hold back valve present( thinking the oldr is acting as a hold back valve). The oldr and the solinoid is being controlled by a t-stat that is on the drop leg of the condenser.Found some lit on this ,but is not sure if i fully understand.If anyone could brake this down to me it will be grately appriciated.