Sam He methods have a very long history in feng shui science in ancient China. One of its famous represnetative methods is the "four big water application sets" 三合水法四大局(3 combination water, fire, metal, wood) used for water dragon.
 
As you can see in the diagram, 24 mountains can be defined into 12 life stages where each stage consists of 2 mountains. This is named "double mountain into 5 elements" method. 雙山五行
 
What shown in the diagram is the 3 combination fire set, where taking the prosperous stage at double mountain (bing, wu) for facing, the water comes in from the birth stage at mountain (yin, gen), and out at the tomb stage at mountain (xin, xu).
 
The above-mentioned 3 combination is the same as used in bazi, eg. Yin, wu and xu EBs then form into the 3 combination fire set. In addition to this, the 3 mountains gen, bing and xin are also being grouped under the 3 combination fire sets.