Glycol Flow Flucuations

[buzzinrizza]

We just opened our second location Des Moines, IA and after a month am having some slight flow issues. The set up is much different than any other brewery I have had experience in due to the distance between brewhouse/fermentation and the jacketed serving tanks. I'll try to break this down as simply and accurately as I can....We have a 10 to Whaley with a 2 HP supply pump on kind of a mid level roof structure. Everything is plumbed in 2" (63mm) ABS and the supply and return both split off in 45 deg wyes to service both locations. One loop goes straight down about 8 feet then services the 7 fermenters and back up the 8 feet to the reservoir. The other branch makes a pretty ridiculous 600 foot loop with about 20 feet of elevation gain to maintain the chilled beer in the 12 serving tanks before making the return and 20 foot drop to the reservoir. My initial concern was that we would lack flow and pressure to the servers which seemed to be the case once we fired the whole thing up with about 15 psi on the lower loop and only about 7 on the upper loop. Valving back a bit on the upper loop return valve got up to 10-12 psi though and all was well. Now all of the sudden a month in things have somehow reversed. Upstairs pressure will climb above 25 psi depending on how many solenoids are open and suddenly the lower loop simply will not get above 8 psi even if the brewer (I am not on site but at original site in TX) backs the return valve completely closed. I suspected a clogged wye strainer in the lower loop but that does not seem to be the case. Now matter what action taken the smaller downhill loop will not get enough pressure but the loop at the end of the insane journey with the huge climb is over normal operating pressure. Kind of Stumped.
Thanks

[Starcat]

System Design

You may have some large design violations in your layout that defy your pump capability etc.
Return valves are never throttled to attempt to " gain pressure " and then only on individual heat exchangers, not on main returns.
Throttling back returns is done to balance an excess of flow across a heat exchanger to get optimum heat transfer.
Its not a good idea to have serving tanks on the same chiller that you are running fermentation and or brewhouse duty.
You need constant glycol supply temp for serving, not a loop that is subject to large swings with other loads.
With some photographs and drawing I may some ideas, but it sounds like you will need some custom refitting to make it work.