Looks like I'm five days late with my version!
If you winterized with the pink antifreeze you can use your Hydro/AquaHot for heating the motorhome either with the electric element or the diesel burner. Due to length of plumbing runs and the complexity of the Hydro/AquaHot it takes about four gallons. If you've less, you may not be fully winterized.
There are two independent liquid systems. One is the operating coolant/antifreeze within the Hydro/AquaHot. It is heated with the electrical element, the diesel burner, the engine or any combination. It never escapes the Hydro/AquaHot system (unless there is a leak!). If maintained at 50% with water it can't freeze. This is the liquid that is pumped through the heat registers to generate heat. It works no matter what is in the other system.
The other system is where the water for human use is found. Normally it is water. But it can be the RV Pink Water System Antifreeze. If you keep the rig heated in the winter, it can always be water. If you ignore the usual forum advice of heading south for the winter, you may want to fill the system with the Pink AntiFreeze if you fear storms, power outages or can't keep the heat on.
The result of the systems being independent is that you can use the motorhome comfortably throughout the winter with a fully winterized drinking water system. Just don't drink the water, flush the toilet, run the ice maker, take a shower or turn on the water pump. You can run the heating system.
In the winter, I always set the two thermostats at 72 degrees while driving. It seemed that it kept up well with the heat loss caused by the cold air going by at 62mph. The diesel burner was not needed as there was enough "waste" heat from the engine to keep up.
