12V Tap for Rheem Heat Pump Water Heaters (ESPHome-Econet)

This part provides a way to tap 12v from Rheem/Ruud Hybrid (Heat Pump) water heaters to power an ESP32+RS485 adapter for ESPHome-Econet without modifying the water heater. Models that lack WiFi provide 12V power over the RJ12 port, but models with built-in WiFi do not. Existing solutions are to either use a separate power source, or to solder a wire to the water heater's control board.

This holder can hold a wire (or better yet, a pogo pin such as the Mill-Max 0973) in place on the 12v test pad without soldering anything to the water heater. It slides over connector J11 (immediately above TP-12V), using the connector to position the wire / pogo pin over TP-12V, and clips over the edge of the board to resist lifting away. The wire hole is angled to avoid conflicts with the plastic cover.

Print it with supports, oriented with the “front” face down so that the layer lines don't make it too difficult to unclip from the board. The rounded edge should be nice and round. It should slide on easily, though it may be difficult to get enough grip to remove it.

Different board variations could require slightly different spacing, but the model is easy to adjust.

No warranties! No guarantees! Use at your own risk! Do not break your water heater!

• You might break something when opening or closing the control panel
• You might break something while removing the black plastic cover (it takes a bit of force and a lot of wiggling)
• You might break something when disconnecting or reconnecting the connector at J11
• You might break something while sliding this part on or removing it
• If the wire comes loose or the part breaks, it might cause a short and break something
• There is high voltage and high power on parts of the control board - a short could cause a fire
• There may be other unanticipated risks
• Use this prototype proof-of-concept part at your own risk
• I accept no responsibility for anything that happens as a result of using this