I am currently fitting a new oil fired boiler in my house. I am not Oftec registered but the engineer who services our boilers has agreed for me to fit it and he will then check it and sign it off for me(hope that's legal). He has advised me to fit a 2 pipe oil system as the burner on my Worcester boiler is situated quite high up on the boiler. Can the return oil pipe run underground beside the supply line and does it re-enter the tank through the top? The supply pipe seems to have a rubber outer covering on it(old original pipe) so should the return pipe be the same type? Thanks for any help.