Regarding the flux for total heat transfer rate:
My model has several soil layers on top of each other and a cooling pipe buried in the very top layer (shown below). Therefore, if I select (a) all wall-interfaces between the soil layers, (b) the wall interface between pipe wall and its surrounding soil layer, and (c) wall interface between coolant and pipe wall, then calculate the net flux for all of them at once and check if the final net flux is lower than 1% of the smallest flux, is that correct?

Thank you!