Just replaced a conventional WH with the Navien NPE-240A2. Our home has the return hot water line and we were running a recirculation pump. Here is my question. We do not have an external pump currently installed, just the internal recirc on the 240A2. Do I need to install an external pump to get closer to instant hot water, or can this be done with just the internal components on the 240A2 with the settings set to external? Currently it takes about 3-4 minutes to get hot water to our primary bathroom (furthest point from the Navien).