The diagram below shows how a central heating system in a house works.
Summarize the information by selecting and reporting the main features, and make comparisons where relevant.

You should write at least 150 words.

The diagram shows how a central heating system in an ordinary house works to provide not only hot water but also heating throughout the house.

The first stage is the introduction of cold water. This is done through the ceiling of the house and stored in a water tank in the upper section of the house. Attached to this storage tank is a pipe which leads to the boiler – where the water is heated – and a pipe which leads to the taps which provide hot water. Pipes also pass through the storage tank which allow for the recycling of water, and pipes to a water tank in the ceiling to allow for easy gravity feed to refill the storage tank. Excess water is fed through an overflow pipe which is either used as cold water throughout the house or is fed back to the storage tank

To provide for the heating of the water for general use and to heat the house, a boiler is located below the storage tank again to allow for gravity feed. Water passes through the boiler, is heated up and then flows to the hot water radiators placed around the house. As the water cools in the radiators it is forced into the recycling pipes and fed back to the boiler. To allow for the upward movement of water, a pump is employed.

Task achievement / Coherence and cohesion / Lexical resource / Grammatical range and accuracy
FAIR
• attempts to address the task but does not cover all key features
• may confuse key features with detail; parts may be unclear, irrelevant, repetitive or inaccurate / Very Good
• arranges information and ideas coherently and there is a clear overall progression
• uses cohesive devices effectively, but cohesion within and/or between sentences may be faulty or mechanical
• may not always use referencing clearly or appropriately / Very Good
• uses an adequate range of vocabulary for the task
• attempts to use less common vocabulary but with some inaccuracy
• makes some errors in spelling and/or word formation, but they do not impede communication / Very Good
• uses a mix of simple and complex sentence forms
• makes some errors in grammar and punctuation but they rarely reduce communication