I just want to touch on what the use of the thermostat is used for in a LP fuel system. The thermostat is open when the coolant temp is low allowing the coolant to enter the vaporizer unrestricted. As the temp. increases over the LP cracking point the LP thermostat restricts coolant flow holding the vaporizer tempature @ 160-170 f. Most manufactures have removed the in line thermostats from the LP systems and have mandated vaporizer draining intervals ranging from 200 to 500 hours to remove the buildup of propalene (crud).