Gas Connection, Leak Check | Lennox International Inc TUA100S, TUA125S, TUA45S

Gas Connection

When connecting gas supply, the length of the run from the meter must be considered in determining the pipe size. A line pressure of 7" w.c. (1.74 kPa) for natural gas should be maintained when sizing piping. A line pressure of 13” w.c. (3.23 kPa) should be maintained for liquefied petroleum (LP) gas. A minimum of 5.0" w.c. for natural gas or 10.4" w.c. for LP/propane gas should be maintained for proper unit operation. For correct sizing of piping, refer to the (American) National Fuel Gas Code ANSI Z223.1 or (Canada) CSA-B149 Installation Code or consult the utility having jurisdiction.

A drip leg should be installed in the vertical pipe run to the unit. In some localities, codes may require that a manual main shutoff valve and union (furnished by installer) be installed external to the unit. Union must be of the ground joint type. A drip leg should be readily accessible to permit cleaning and emptying. See figure 9. Leave a minimum of 4" (102mm) clearance between electric box and drip leg.

A 1/8" NPT plugged tap shall be installed immediately upstream of the gas supply connection to the heater.

Leak Check

After gas piping is completed, carefully check all piping connections, (field and factory), for gas leaks. Use a soap solution or other preferred means.

CAUTION - DO NOT use matches, candles, flame or other sources of ignition to check for gas leaks.

IMPORTANT - The heater and its individual shut off valve must be disconnected from the gas supply piping system during any pressure testing of that system at test pressures in excess of 1/2 psig (3.45kPa).

The appliance must be isolated from the gas supply piping system by closing its individual manual gas shutoff valve during any pressure testing of the gas supply system at test pressures equal to or less than 1/2 psig (3.45kPa). See figure 10.

NOTE - In case emergency shutdown is required, shut down main gas valve and disconnect main power to unit. These devices should be properly labeled by the installer.