i unfortunately ran my propane tank down and now my boiler will not re-fire. i attempted to reset by turning the igniter to the off position then shutting down power to the unit and waiting the five minutes to clear any gas. when following the start up procedure the flame led illuminates momentarily and the power led stays on. in that brief moment that the flame led is on you can hear the unit making an effort to fire. i belive the pressure is too low (reading @ 20 psi) and the unit may need to be primed. if that is the case how do i accomplish this without calling on a field tech?