Quick Domestic Heating Underground Oil Pipe Question

[Woody12]

I'm just about to dig the trench for the oil pipe (gravity flow), from the tank to the boiler, for our plumber who returns from his holiday's next week.

I'm sat reading the OFTEC website and have just come across this:

External/Exposed Pipes: In order to prevent air locks, external gravity piping should run in a continuous rise following the direction of flow.

Does this mean that the oil pipe must rise from the tank to the boiler when underground, as technically it's external, yet underground? Or does this just apply to when the pipe comes out of the ground and up the external wall and into the boiler?

The oil tank is higher than the boiler.

 

[Woody12]

Anyone?

 

[leakydave]

Avoid obvious high points but don't worry if the trench is basically a straight run. You shouldn't need to get your spirit level on every inch of pipe.

I prefer to run the oil line in a plastic ducting, as used on plastic pipe in concrete.

Halfway to surface fit Oil Warning Marker Tape [Brown] to warn any future archaeologists.