Why Won't the Dryer Gas Line Screw On?

Incorrect Supply Hose

• Gas dryers require a specific type of supply hose, called a gas flex line. Inexperienced do-it-yourselfers might confuse other flexible supply hoses for gas flex lines, such as PEX piping or braided water lines. In the store, manufacturers clearly mark approved gas appliance hoses as "gas dryer lines" or "gas appliance lines." While some gas flex lines are lined with a yellow, plastic coating, others resemble corrugated piping. Consult your dryer manufacturer's installation instructions to determine the correct hose diameter for your appliance. Hose diameter determines the hose's fittings' diameters, which must match the size of the appliance's and supply valve's fittings.

Appliance-side Connections and Adapter Requirements

• Appliance-side gas connections vary according to your gas dryer's make and model. Some dryers arrive with only a pipe nipple protruding from the rear, some have a flare nipple and others feature a handle-operated valve. Gas valve fittings and hoses connect via specialized flare fittings. Male flare fittings have a conical tip and female flare fittings have a corresponding conical depression. If the gas inlet at your dryer's rear is a straight-ended pipe nipple, you must either install an approved gas valve or a flare adapter on the nipple before the hose will screw on.

Supply-side Connections and Adapter Requirements

• The supply-side connection, located on the wall behind the dryer, usually consists of an in-line, dedicated gas valve for the dryer. Because gas valve outlets are flare fittings, you must ensure that the side of the supply line that you are trying to screw on to the valve is flare. If both the supply and appliance side require flare fittings, but your hose is only flare on one side, you must adapt the pipe-thread side of the hose to flare.

Pipe-Thread Sealant

• Never apply pipe-thread sealant to flare fittings. Flare fittings' conical tips and depressions create a gas-tight seal without sealant. On the contrary, applying sealant to flare fittings might compromise the flare fittings' seal. However, you must always apply pipe gas pipe-thread sealant to pipe-thread fittings. On pipe threads, sealant not only lubricates for tightening but seals gaps between threads. You can test your new connections for leaks with a leak detection compound.