sean, i need to know how you built a glycol warmer? I have separate ports that I built into my system that I can plumb with warm water to raise temps, but I have never heard of a glycol warmer before. Apprise me on this....
It was just a spare glycol unit we had lying around (missing its compressor) with a 1500 W water heater element in the reservoir and controller/relay set for ~30°C. Each of the tanks had a single-stage controller and a pair of solenoid valves, one NO, one NC. So either warm or cold glycol was always flowing through the jackets (I did put a manual valve on each to save energy when they were empty). It was the only way I could think of to do it with a single jacket on the tanks, and it was far from an ideal solution. Turns out there are some things that will actually metabolize propylene glycol; I guess sub-freezing temperatures will kill them off in a normal chiller setup.
If I had two jacket zones like you do, I'd use water for the warm side.