Got ya, I was getting it mixed up with my setup, and crossed in my head which way the pump was pushing. So if your vegi return is in between the cold heater core line and degas bottle, the path of least resistance is to the degas bottle, and not backwards through heater core to the hot side. Probably if anything, you may have lost a little flow through your heater core, but same for me too, Vegi getting heated is more important than me getting heat in the cabin. :thumb:You are confused. ITs taking water that comes from the water pump, on its way to the heater core and its pumping it through my coolant loop and back - you can't see the return line but it goes to the de gas bottle. The inlet tube is pointing at the engine, the out let is pointing to the rear.