I have an older Grumman Sunstream solar system with a SigmaRho 180 differential controller. The controller is starting to go after 30 years. Either the Goldline GL30 or theTeckmar156 controller would be an appropriate replacement, using the existing 10k ohm sensors. The pumps draw about 1.5 amps, well within the controllers' specs. This is a simple on/off control strategy. The existing differential is 4 deg. and not adjustable. The Goldline seems a bit simpler. I'm looking to basically duplicate what's there. Any experience with reliability with either of these two units? thanks, Mark S.
I am partial to Tekmar, especially because you can use the 157 and get variable speed performance for a tiny up-charge. However, whatever you, do I would strongly recommend that you replace the temperature sensors at the same time. Generally they do not last all that long. The Tekmars will come with new ones. Check the resistance on the wiring while you are at it. Connections fail first.
... of checking sensors to see how they're doing, is to put both is a glass of water (keep the water level low enough so you don't completely immerse the sensors) and then measure conductivity through both. They should read the same. If not, it's new sensor time. I agree that connections are a problem. I fill wire nuts with silicon before connecting wires and then aim them up so water cannot collect in the wire nut. Given the opportunity, mice like to nibble at wires as well.