the placement of third orifice 518 need not be adjacent or on the same surface as second orifice 516 fitting 508 may be a brass fitting having u215b u2033 npt u00d7 u00bc u2033 hose barb seal 506 such as a seal constructed from teflon material may be interposed between fitting 508 and inlet block 504 to ensure the connection between these two elements is able to withstand the pressures generated by the gas source in embodiments where two electrical leads are connected to the heating element inlet block 504 may also be grounded inlet block 504 may further define hole 528 which may in turn be threaded to enable acceptance of a screw or other connection for a grounding wire the gas source may be a pump to deliver ambient air at a pre defined pressure alternatively the gas source may be a tank containing a pressurized gas such as oxygen suitable pumps include the gast 30b pump available from gast manufacturing inc benton harbor mich the thomas 5030 available from thompson pump amp machinery slidell la the al 30b and the alita 15b both available from alita industries arcadia calif gas flow may be in the range of 20 35 standard liters per minute slpm at 25 35 inches of water column in wc and may be in the range of 25 30 slpm at 25 35 in wc excessive gas flow may cause localized rapid burning of fuel potentially leading to rapid outgassing of trapped moisture the effect may appear to be similar to popping of corn inlet block 504 may further define a channel comprising two chambers a first chamber.