I assume that your tank has a pressure valve on the fitting which is attached to the tank and controlled by the solenoid switch.

With the lines charged (ready to light instantly and under pressure) butwith the valves closed on the stove, oven, heater(s), etc. Close the valve on the tank but leave the solenoid on. Check the pressure in the line from the tank. Wait as long as you can (hours) -- then check to see if you have any loss in the lines through the system.