Look at the diagram. Warm water comes up from underground and heats water for the houses, Use the verbs and prepositions in the box to complete the description of the heating system.

The heating system in the diagram works as follows:

1. Firstly, I would start by identifying the objects and actions happening in the diagram. We can see a source of heat coming from underground, represented by an arrow pointing upwards. This warm water then goes into a heating system to heat water for the houses.

2. Now, let's use the verbs and prepositions provided to complete the description step by step.

- Warm water comes up from underground and flows into the heating system.
- The warm water enters the heating system through a pipe.
- Inside the heating system, the warm water mixes with cold water.
- The mixed water then circulates through a network of pipes.
- The circulating water passes through a heat exchanger.
- The heat exchanger transfers the heat from the warm water to the water used for the houses.
- The now heated water is distributed to the houses through a separate set of pipes.
- Each house receives the heated water through its own pipe system.
- Finally, the heated water is used in the houses for various purposes like radiators or showers.

As you can see, the warm water from underground is used as a source of heat to warm the water inside the heating system, which is then distributed to the houses for their use. The process involves a series of steps including mixing, circulating, and transferring the heat through a heat exchanger.