Rheem XR90 Series Use and Care Manual - Page 11

WARNING: Do not attempt to convert this water heater for use with a different type of gas other than the type shown on the rating plate. Such conversion could result in hazardous operating conditions. Gas Supply The branch gas supply line to the water heater should be clean 1/2" black steel pipe no more than 40 equivalent feet long or other approved gas piping material. A ground joint union or ANSI design certified semi-rigid or flexible gas appliance connector should be installed in the gas line close to the water heater. The National Fuel Gas Code (NFGC) mandates a manual gas shut-off valve: See (NFGC) for complete instructions. If flexible connectors are used, the maximum length shall not exceed 36" and must meet the requirements in ANSI Z21.24-Connectors for Gas Appliances. If lever type gas shut-offs are used, they shall be T-Handle type. Compound used on the threaded joints of the gas piping must be of the type resistant to the action of LP gas. Use compound sparingly on male threads only. Where a sediment trap is not incorporated as part of the appliance, a sediment trap shall be installed downstream of the equipment shutoff valve as close to the inlet of the appliance as practical at the time of the appliance installation. The sediment trap shall be either a tee fitting with a capped nipple in the bottom outlet or other device recognized as an effective sediment trap. Do not use excessive force (over 31.5 ft lbs.) in tightening the pipe joint at the gas control (thermostat) inlet, particularly if teflon pipe compound is used, as the valve body may be damaged. The inlet gas pressure to the water heater must not exceed 10.5" w.c. for natural gas, or 14" w.c. for LP gas. For purposes of input adjustment, the minimum inlet gas pressure (with main burner on) is shown on the water heater rating plate. If high or low gas pressures are present, contact your gas supplier for correction. WARNING: Never use an open flame to test for gas leaks, as property damage, personal injury, or death could result. Leak Testing The water heater and its gas connections must be leak tested at normal operating pressures before it is placed in operation. Turn on the manual gas shut-off valve near the water heater. Use a soapy water solution to test for leaks at all connections and fittings. Bubbles indicate a gas leak that must be corrected. The factory connections to the gas control (thermostat) should also be leak tested after the water heater is placed in operation. Pressure Testing the Gas Supply System The water heater and its manual gas shutoff valve must be disconnected from the gas supply piping system during any pressure testing of that system at pressures in excess of 3/8 psi (10.5" w.c.) for natural gas, or 1/2 psi (14" w.c.) for LP gas. The water heater must be isolated from the gas piping system by closing the manual gas shut-off valve during any pressure testing of the gas supply piping at pressures equal to or less than 3/8 psi (10.5" w.c.) for natural gas, or 1/2 psi (14" w.c.) for LP gas. 11