L4 Hot Water Risks and Hazards

Contents

Correct valves Things to check Health and safety considerations Common visual faults Faults table

Safety Risks to people Risks to buildings Questions Know what you're looking at

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Risks, hazards and how to mitigate them

Safety

Hot water safety protects residents and maintains the building's integrity. Hot water can be a significant health risk if not installed properly and regularly inspected and maintained.

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Risks to people

All modern hot water systems are connected to electrical controls.

Legionella is a bacteria that grows in water between 20-45 °C.

Carbon monoxide (CO) is a silent killer; it is odourless and colourless.

HSE guides - why water is heated to high temperatures and how to reduce the risks.

Electrics

Legionella

Carbon monoxide

Burns and scalds

Learn more about leaks

Learn more about explosions

Risks to buildings

An explosion is the most extreme risk with domestic hot water systems.

Leaks are the most common and obvious risk to a building.

Explosion

Leaks

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See some of the issues leaks can cause by selecting the icons on the images.

• In both situations repairs should be undertaken immediately to avoid it worsening.

• It may involve landlord or home insurance to cover these sorts of risks.

Risks to the building and fabric

LOREM IPSUM DOLOR SIT

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If a cylinder explosion fractures or rips out the gas pipe, this can result in a fire.

Explosions pose the greatest danger. Safety features like vents and relief valves help manage overheating by releasing water. Water takes time to boil and change state. Under pressure, water remains liquid at higher temperatures. If this pressure is released, it results in rapid expansion or an explosion - a large volume of water heated above 100 °C, remaining a liquid as it can't escape. Eventually, the pressure will be too great causing a mass amount of water to vaporise into a gas. Read about a cylinder explosion:

Risk of explosion

• Cylinder explodes
• Boiler leaks acids
• Boiler leaks pressurised boiling water

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• Hydrogen chloride
• Nitrogen
• Carbon monoxide

• 10°C - 20°C
• 20°C- 45°C
• 40°C - 55°C

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2. The risk of Legionella increases when water is stored at what temperature?

3. What is the most extreme risk a hot water system can pose to a building?

1. What is the odourless and colourless, poisonous gas produced by incomplete burning of carbon based fuels?

Try a few questions

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If the cylinder is in an airing cupboard and storage tanks in the loft...

If the cylinder has an expansion vessel and pressure relief valves...

If it has a combination boiler ...

it is a gravity system

it is a pressurised unvented system

it is a sealed system​

Identify the system type!​

Visually checking a system can provide valuable information about its condition, such as the age and maintenance of taps, pipework, and appliances. Refer to technical information or manufacturer instructions to check for proper installation and service history, including details about the installer and each service performed on the system.

Know what you're looking at first!

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Correct valve for the correct job!

Gate Valve - Low Pressure Isolation

Lever Isolation Valve

Water Isolation valve

Gas Isolation Valve

Now you can check for defects that might lead to unsafe situations. Key things to check on each system will slightly differ, but it will help to identify possible DIY works, age-related issues, or poor workmanship. Do you recognise these valve types?

If in doubt, talk to a professional!!​

Tradespeople must be occupationally qualified and registered with a competent person scheme to work on hot water systems. If you suspect something is incorrect or unsafe, or you are unsure, seek advice from an approved, qualified plumber.

Check for signs of leaks - wet or damp patches. Check for signs of scaling on the whole system, this can diminish efficiency and risk blockages. ​ Listen, run the hot taps and if you hear loud banging or vibrating, the system might not be clipped or supported properly.

Things to check​

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Health and Safety considerations​

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Common Visual Faults Table

Boiler Guide: Common Hot Water Cylinder Problems

British Gas: What to do if you have no hot water?

EDF Energy: 10 common boiler problems

Common Visual Faults

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