Propane fuel is stored as a liquid at high pressure.  When propane is used as 
fuel, it must first pass through a regulator where it is allowed to expand
and turn into a vapor.  Once a vapor, the fuel is allowed to mix with outside
air in the mixer and burned in the cylinder as fuel.

The propane regulator has two coolant hoses attached to it, which in a normal 
installation is used to prevent the regulator from freezing by allowing
hot engine coolant to flow through it.

Our installation uses this feature only as a redundancy.

In Beatrice the Van(c) our group has installed a seperate 12v coolant pump 
to run coolant through a completely seperate system.  Here's how it works:

Coolant starts at the pump, flows out to the regulator, into the heater core
and back to the pump.  When the blower fan is switched on, ambient air flows
through the heater core, providing enough heat to prevent the regulator from
freezing solid, and using the cooling effect of expanding liquid fuel to cool
the passengers on a long van journey. 


[Detailed pics coming soon]