The diagram below shows how a central heating system in a house works.
Sample Response
The given diagram shows how a central heating system of a house works. As is observed from the illustration, the central heating machine comprises several mechanical aspects and forms a complex system. According to the given illustration, for the central heating machine to work the cold water supply is required and this water flows to the storage tank and the overflow pipe is there to store the excess water in storage. The water is passed through a boiler which is either gas or oil driven and a pump is connected with it. The radiators are connected with the boiler and these radiators are made of small tubes. When the cold water passes through the pump and boiler, it gains temperatures and become hot water and from the water taps, the house members get hot water. Thus the whole system that covers the house keeps it warm. In summary, the central heating system mainly works by flowing water through the house and increasing the temperature of it.
IELTS Writing Correction
- 1. Use system central heating system
- 2. Natural noun components
- 3. Add comma for the central heating system to work, a cold water supply is required
- 4. Process accuracy the overflow pipe removes excess water from the storage tank
- 5. Hyphenation gas- or oil-driven
- 6. Diagram accuracy radiators are connected by small tubes
- 7. Verb agreement it gains heat and becomes hot water
- 8. Natural phrase household members
IELTS Writing Criteria Scores
Detailed feedback by IELTS writing criterion after the annotated essay.
Task Achievement
The response identifies the main components and gives a generally understandable process, but some details are inaccurate or vague. It does not clearly explain the full cycle from cold water supply to storage tank, boiler, radiators, hot taps, and return flow.
Describe the system step by step: cold water enters, is stored, passes to the boiler, is pumped through radiators and hot taps, and circulates through pipes.
Coherence and Cohesion
The answer has a basic sequence, but it is mostly one paragraph and the process stages are compressed into long sentences. The summary repeats the main idea without clarifying the cycle.
Use separate sentences for each stage and add sequence links such as 'first', 'then', 'after being heated', and 'finally'.
Lexical Resource
Vocabulary is understandable but sometimes inaccurate: 'machine', 'mechanical aspects', and 'gains temperatures' are not natural for this diagram.
Use process vocabulary such as 'system', 'components', 'flows', 'is heated', 'circulates', 'radiators', and 'pipes'.
Grammatical Range and Accuracy
There are frequent article, agreement, and verb-form errors, though the message is mostly clear. Some sentences are too long and need clearer subordination.
Rewrite passive process sentences carefully: 'water is heated', 'hot water is pumped', 'radiators are connected'.