The fuel supply piping between the tank and the appliance shall have what diameter?

The correct diameter for fuel supply piping between the tank and the appliance is 3/8 inches, which is specified to ensure adequate fuel flow and pressure delivery to the appliance. This size provides a balance between sufficient capacity for fuel delivery and ease of handling and installation.

A diameter of 3/8 inches is commonly suitable for residential oil-fired appliances, as it can accommodate the necessary volume of fuel without causing excessive pressure loss or restricting flow. It effectively supports the operational efficiency of the heating system while remaining compatible with typical fittings and components in residential installations.

Using smaller diameters, such as 1/4 inch or even 1/2 inch, may lead to problems with fuel delivery, including inadequate supply during higher demand, which could hinder the appliance's performance. Adequate piping size is crucial for maintaining system efficiency and ensuring reliable operation in heating applications.