The Right Size of the Gas Pipe That is Used for Four Appliances

Choosing gas appliances for your household, is easy and a smart idea. Their installation is something else. First, before installation, make sure your gas pipe respects the sizes (diameter and length) required by local building codes. The local building code specifies also, the proper type of material for the pipe.

Photo by Kaminski + PewLook for kitchen design inspiration

Pipe Size:

Suppose you want to install four appliances such as water heater, furnaces, stoves and dryer. When calculating the pipe diameter, factors taken into accounts are:

1| The specific gravity of the gas
2| The maximum demanding quantity of gas
3| The allowable pressure loss, between the source and connection
4| The length of pipe and the necessary number of fittings

Generally, the size of the pipe can be between ½” and 3” diameter.


The minimum input required, for each appliance to function normally, determine the minimum BTU required by each appliance.


1| Minimum BTU for a gas dryer – 35,000 cubic ft / hour
2| Minimum BTU for a water heater – 35,000-50,000 cubic ft / hour
3| Minimum BTU for a gas oven – 65,000 cubic ft / hour

The capacity (cubic ft / hour) is proportional to the diameter and the length of the pipe.


1| L = 10 ft, D = ½ “will deliver 175 cubic ft / hour
L = 125 ft, D = ½ “will deliver 44 cubic ft / hour

2| L = 10 ft, D = 3” will deliver 11,000 cubic ft / hour
L = 125 ft, D = 3”will deliver 2,950 cubic ft / hour


You should seek the services of a qualified professional to install a gas appliance. This experienced professional will be able to calculate the right diameter and length of the pipe, depending on the amount of gas necessary for a proper function of the appliances.

A gas pipe is made from black or galvanized steel or even from iron.

NOTE: When you need to cut a pipe, you should know that the interior diameter has to be maintained.

Check the Plumbing System Before Moving In – Smart Ideas (