Hydronic diesel-fired Heating system

As stated earlier, the camper is easily removed from the chassis and can operate autonomously when detached.  It has its own fuel supply, electrical and charging systems, etc.  However, when the camper is mounted on the chassis, they both work together in a 'symbiotic' relationship.

While the cook stove is a propane appliance, fueled from a dedicated 10 lb. cylinder, both camper heating and potable water heating are accomplished hydronically.  A closed system of fluid (ethylene glycol engine coolant) transfers heat to a small water-to-air heat exchanger for warming the camper, and to a water-to-water heat exchanger for potable water.  

The fluid can be heated one of two ways: by the chassis' engine, or by a diesel-fired Espar Hydronic 5 furnace mounted in the camper.  Since both the chassis and camper have sources to heat the fluid, one can provide heat to the other through quick-coupled hoses.  When the chassis' engine is running, engine coolant flows into the camper to create a warm cabin and hot water for the sink.  When parked and camping, the Espar Hydronic 5 furnace provides heat for the camper, and also can pre-heat the chassis' diesel engine for quick, easy starting.

Long before the camper was ready for the furnace, I had to try it out!  Here's my temporary test-stand.  The bucket on the fuel tank contains 2 gallons of diluted antifreeze, which is pumped by the Espar Hydronic 5 through a Red Dot heater core and then back into the tank.  It fired right up on the first attempt, and after only 12 minutes of operation, dropped back to low speed when the water temperature reached the high limit. 

Here's the Espar Hydronic 5 mounted in an insulated, vented compartment on the right side of the camper.  It is exhausted just in front of the right rear wheel...

Fuel for the Espar is contained in a marine fuel tank, located within the right side trapezoid compartment behind the right rear wheel.  The capacity is six gallons, and provides for many hours of heat with the Espar using approximately 0.1 gal/hr on low speed.  While it is normal practice to draw fuel from the chassis' tank, this system allows the camper to be autonomous when removed from the chassis.   

Here you can see the plumbing at the OM352A engine.  With the engine operating, coolant flows toward the camper from the "Y" fitting and returns at the block drain.  Coolant flows in the reverse direction when the Espar is providing the heat.  (The bottom of the "Y" goes to a 1250W electric block heater.) 

Coolant within the camper is distributed through a manifold built from copper.  The ball valves allow flow selection through three circuits: Engine, Camper Heat, and Water Heater.  The micro-switches provide an external visual representation of the position of the valves at the control panel, and also prevent the Espar furnace from starting or running if all valves are closed.

Here's the homemade control panel and Red Dot heater core with two-speed fan below...

Note the timer at the upper right of the FURNACE CONTROL panel.  This is an Espar "Mini-timer" and can be programmed to turn the furnace on at various times of the day for user-definable periods.  This works great when camping, since no heat is generally needed at night while sleeping.  The furnace can turn itself on in the morning, thus heating the camper, potable water, AND chassis engine (if desired) before we get out of bed.