We have been using a nice little Jabsco pump (jabsco 59510-0012 centrifugal pump) to push engine coolant through the HWH heat exchanger and to a cabin heater. Magnetic drive (no seals) and 12 volts but a bit pricey at $150.
Recently discovered that this pump started life as a part for MB and other German cars. The search led to MTC #3033, an equivalent pump on Amazon for about $50 plus shipping.
Just thought I’d pass that along…
Quent