HEATING
Instead of heating the van interior in cold weather, I let the van interior get cold at night and stay warm with a 12 volt DC bunk heating pad under the zero degree sleeping bag.  The power used by the heating pad is offset by the refrigerator using less power because refrigerator runs less in a cold van.  The heating pad is quiet for stealth city camping.  An Espar type heater is too noisy for my use.  The heating pad keeps the body warm but on colder nights my head gets too cold.  The cold head problem is solved with a balaclava.  The other problem with not heating the van interior is getting up into a cold van in the morning.  That is solved with a gas engine that can be idled.  Bought the remote start option so I can start the engine before getting out of bed.  Heat the interior from the dash vents and with a 750 watt AC electric baseboard heater that is located under the bed.  The dash heater controls are set the night before for maximum heat. The power for the baseboard heater comes from the vehicle powered inverter.

The 36" x 60" bunk heater is made by Electro Warmth.  Cost is around $100 for the pad. The pad has a temperature control knob with 7 settings.  Have never used a setting higher than # 2.  Heating pad works very well with temperatures above 20 degrees.  Have not used it below 20 degrees so do not know how well it will work at lower temperatures.  The pad uses 6.2 amps when it is on.  The temperature is controlled by cycling the power on/off.  Lower settings has more off time than on time.  Higher setting have more on time than off time.

The conversion electrical design includes a 1000 watt pure sine inverter powered by the vehicle 12 volt system when the engine is running.  The 120 volt AC output from the inverter is switched the night before so the inverter will power the electric air heater in the morning.  The electric air heater can also be powered by shore power if shore power is available.  The air heater has a thermostat to automatically  control the heater.

Have attempted to retain some of the body and heating pad heat in an insulated tent around the bed platform.  There is a insulated back curtain that hangs from the ceiling down past the top of the bed platform.  The front curtain is made up of three parts.  A center curtain from the ceiling to the floor and two side curtains from below the upper cabinets down to the top of the bench seats.  The curtains wall off the sleeping area.  The front curtain can be installed 27" in front of back curtain for a tent for one person or 54" in front of the back curtain for a tent for two people. Tested last winter and did not get the results that I expected.  Only  a few degrees higher temperature inside the tent than temperature outside the tent inside the van.  Will do more testing this winter.

Another source of heat on sunny days is to turn on the house inverter and heat the shower water tank.  Tank is not insulated so heat will be radiated to the interior.  The inefficiency of the inverter will also provide some heat.  Can be used when there will be excess power from the solar panel.

One negative to not heating the van interior is the 23 gallon fresh water tank and piping can freeze.  The 10 gallon gray water tank is under the van floor so it can be emptied in cold weather.  The 6 gallon shower water tank can also be emptied.  Need to install some 12 volt heating to the fresh water tank and piping that is controlled with a thermostat.

The shower water is heated in a 6 gallon stainless steel tank with a 625 watt 120 volt AC heating element.  A thermostat turns the power off at water temperature of 95 degrees in about 45 minutes. The heating element can be powered from three sources.  The sources are shore power, "shore power" from the vehicle powered inverter or power from the house inverter/battery.  Using the vehicle powered inverter requires the engine to be running.  Using the house battery requires full sun weather conditions so the excess solar panel power can be used for water heating.

 

COOLING
Cooling is done with air flow.  There is a 4" square hole in the floor on driver side in front of the rear wheel housing under the refrigerator.  Hole has a cover so hole can be open or closed.  The hole is left open 95% of the time.  Closed on dusty roads or sometimes at night in cold weather.  There is a Maxxair roof fan installed at the back of the van over the bed platform.  Since heat rises the natural air flow is up through the hole with cool air from under the van and out the open Maxxair roof fan opening.  Seldom power the fan.