Marshall O,
Did you install a larger relay in the box, say a 10 or 15 amp, in the box and have the temp controller control that? Being a service tech I think about those things. The amp draw on the 5 amp relay for a chiller might be a little much, cause arcing and burning out of the points in the 5 amp controller relay. For my application, I'm only running a 150 watt heater, which pulls 1.3 amps so it's not an issue, but with a chiller kicking on and off the amps a refrigeration compressor draws at startup it might be a bit much. I repair commercial lobster tanks so I know about this first hand.
I have a bunch of convection ovens in the field that the control relays are on the main board. After several years the points burn out and the oven won't heat or worse fuse together and the thermal overload trips. I kind of scratch my head as a service tech and think, "what were the designers thinking when they engineered this?" They probably should have had the control board energize a PID solid state relay or a old reliable magnetic coil relay which is replaceable at a few hundred dollars instead of $3000 for a complete new control board. This is the issue I have with Blueline, JBJ, Finnex heater controllers. After my Finnex controller failed, in the "off position", thank God I opened it up. I found a very tiny relay with it's points charred with no amperage rating on it that I could find.