The diagram below shows how a central heating system in a house works.
Sample Response
This diagram provides an overview of a domestic central heating system. It shows how the tanks, boiler, pump and pipesthe tank, boiler and pipes ensure hot-water circulation through the radiators and a separate supply to the tapsa constant flow of hot waterto both the radiators and the taps.
The cold water enters the roof tankenters the house and is stored in a water tank in the roofa water storage tank in the roof. From there, water flows down into the heating circuitFrom there ü flows down to the boiler, located on the ground floor of the house.
The boiler, which is fuelled by gas or oil, heats up the water as it passes through it. The hot water is then pumped round the house through the pipe networkthrough a system of pipes and circulates through the radiatorsflows into the radiators, installedlocated in different rooms. The water circulates through the radiators, which have small tubes connected to themsmall tubes inside them to transfer heat into the roomsto help distribute the heat, and thereby warming each roomthis warms each of the rooms. Hot water from the storage tank is directed to the tapsSome of the water is directed to the taps to supply the household with hot waterto provide hot water for the house.
Once the water has been through the pipes and radiators, it is returned to the boiler to be re-heated and circulated round the house again.
Introduction: First sentence. Overview: Second sentence.
Key features: Entry of cold water into boiler; circulation of hot waterto radiators and taps; return of waterto boiler.
Supporting information: direction of flow; types of boiler; location of radiators; radiator tubes
Paragraph breaks: The paragraph breaks mark stages in the process.
Linkers: and, from there, then, once, again Reference words: it, both, there, which, this
Topic vocabulary: enters, stored, roof, flows, ground floor, located, passes, pumped, system, circulates, heat, directed, returned, re-heated
Less common vocabulary: ensure, fuelled by, heats up, distribute the heat, warms
Structures: An appropriate mix of active and passive structures and a range of sentence types are used.
Why this response received Band 6.5
The process description initially follows a clear sequence from water entry through heating, circulation and return, using mostly effective paragraphs and fluent language. However, it inaccurately merges the roof feed tank and storage tank, oversimplifies how hot water reaches the taps, and then appends substantial study notes that are not part of a Task 1 report. Remove the notes and describe the separate tanks, pump and connected flows precisely.
IELTS Writing Criteria Scores
Task Achievement
The main heating cycle is described and an overview is present, but the separate tanks and tap-water route are misrepresented and substantial irrelevant study notes are included.
Describe the roof feed tank, storage tank, boiler, pump, radiator circuit and tap supply as distinct connected components, and omit all commentary about the writing.
Coherence and Cohesion
The report section progresses logically through the process with effective paragraphing, but the appended labels and notes abruptly disrupt the unified response.
End after the process description and organize the body around cold-water intake, heating and distribution, and the returning circulation loop.
Lexical Resource
The report uses varied and generally precise process vocabulary, with only minor slips such as merged words and a corrupted reference word.
Proofread for small transcription errors and distinguish component names precisely, especially the feed tank and storage tank.
Grammatical Range and Accuracy
Complex and passive structures are used with good control in the report, while errors are occasional and meaning remains clear.
Refine pronoun reference and final proofreading so forms such as the corrupted subject before flows and merged words are corrected.
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IELTS Academic Writing Task 1
The diagram below shows how a central heating system in a house works.
Your response
Write the task yourself, then compare your choices with the annotated response.