What size is the pressure tap in an oil pump for the low-pressure gauge?

The correct answer highlights that both 1/4 inch and 1/8 inch pressure taps can be utilized for low-pressure gauges in oil pumps. In the context of HVAC systems, particularly with oil burners, it's common for low-pressure gauges to connect to these standard sizes depending on the specific design and manufacturer of the pump.

Using a 1/4 inch or 1/8 inch fitting allows for proper integration with most gauge systems, ensuring accurate pressure readings necessary for efficient oil burner operation. The choice between the two often depends on factors like the layout of the system and the specific application requirements. Thus, having both options available provides flexibility in installation while still maintaining functionality and adaptability for the technician working on the oil system.