When designing a layout and sizing an installation, care must be taken to ensure an optimum system. Using good engineering practice, a system can be designed using the smallest allowable size of tube that will supply gas to the appliance with the required volume and pressure, and in accordance with code tables and pressure drops.

Frequently, for a typical single-family dwelling, the gas company will install the meter outdoors. It may be recommended that a minimum size of 1/2" NPS steel pipe be used to pass through the exterior wall of the building, and it should be anchored to prevent movement. The transition to copper is then made at any convenient location inside the building, see Figure 1.


Figure 1:Typical transition to copper tube when there is steel pipe from the exterior meter.

Copper tube may be connected directly to the meter, in which case the meter is supported by a bracket which provides a secure support.


Copper tube connected directly to the meter, which is supported by a steel bracket.

There are two basic types of layout. In the first, there is a main and then branch runs to supply the various appliances. In the other type, after the meter, there are individual runs to each gas appliance. A gas distribution manifold may be used, as shown in Figure 2, depending on the number of appliances, their sizes and the layout.


Figure 2: Schematic diagram of a distribution manifold system.

In apartment installation, multi-meter manifolds are frequently used to provide individual metering. A typical method of providing multi-meter manifolds for a low-rise building is shown in the photo below, and that for a high-rise installation in Figure 3.


Low-rise residential apartments, industrial complexes and strip malls, frequently have multi-meter manifolds installed outdoors on exterior walls.


Figure 3, above left, is a typical example of vertical subdivision concept, which simplifies the metering of gas consumption by condominium owners, and apartment tenants. At right, a multi-meter manifold during installation in a meter closet, with the copper gas supply lines to the individual apartments at the ceiling.

They are examples of the vertical subdivision concept, which simplifies the metering of gas consumption for condominium owners and rental apartment tenants, as mentioned previously.

A 7" w.c. (1.75 kPa) house layout with branch runs is shown in Figure 4, and one with individual runs is shown in Figure 5.


Figure 4: A 7" w.c. System with Branch Runs.


Figure 5: A 7" w.c. System with Individual Runs.

Typical 2 psig/7" w.c. combination layouts are shown, in Figure 6 a system with branch runs, and in Figure 7, with individual runs.


Figure 6: A 2 psig System with Branch Runs.


Figure 7: A 2 psig System with Individual Runs.

A gas appliance is marked with its gas demand or input rating on its appliance rating plate, or the information can be obtained from the appliance manufacturer. The sections of a system are sized individually by using the longest run in each section and the total load that it must deliver. If there is a branch in the line to an appliance that is unknown, then the branch should be made the same size as the main supply line.


Soft copper tube entering a low-rise apartment building from a multi-meter manifold, with individual meters for each apartment, on an outside wall.

Individual temperature control. A compact warm air furnace fed by a 1/2" O.D. copper gas line, installed in the closet of an apartment suite.