Last night we slept in the motorhome with the Espar/Hydronic heating the coach. The outside temps were 35 degrees. I have a switch for the Espar that will run the Espar but the dash fans only come on via the thermostat. When the thermostat would call for heat, the dash fans along with the hydronic heaters would turn on. Within probably a minute or so, the coach would be at temperature and the thermostat would turn off the dash fans and hydronic system.
I have great confidence that the Espar heat will provide all the heat we will need even when temps are close to zero.
The part I didn't like was the fact that the motoraide connection only heated the water heater to 95 degrees. While this will work in keeping the pipes from freezing, I would expect to get more heat from the engine. Today I'm going to try and install a second solar water pump (5watts) right before the water heater in the motoraide Hose. We'll see if this helps. Also, I need to review my motoraide hose routing.
Espar was great last night, giving me the confidence that it'll handle the real cold.