Hi Aaron, Years ago I installed a Grundfos pump with an integrated timer that used the cold water pipe as the return line. A special temperature valve below the most distant sink made this possible. I gave up on this arrangement because the cold water line was hot.
I reused this pump on our current house but didn’t use the diverter value. I replaced old water lines with pex (insulated) and added a dedicated return line to circulate hot water. Note: this required two check valves to keep the flow going in the proper direction.
I could set the timer pins on the pump but I prefer to control the pump only when needed. So I added a smart switch controlled by Alexa. “Pump on” or “Pump off” 4 minutes of run time gives me hot water by the time 2 cups of water has passed. Sometimes I’ll forget to turn off the pump.
Next, I’ve played with the timer feature on the smart plug but haven’t found a solution to have the pump turn off after 5 minutes by default. Have you figured out a way to do this?
Grundfos pump: UP15-10SU7P/TLC