HTR1 revision notes
Fires and wall heaters — flueing, spillage testing and atmosphere-sensing safety.
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BS 5871: Hearth Sizing, Spillage & Atmosphere Sensing
Gas fire and space-heater safety checks
The big safety themes for gas fires and heaters: air supply, flue performance and the fuel bed.
Gas fire fuel beds, radiants and coals
Why the layout of coals, radiants and the fuel bed in a gas fire is a safety matter, not just looks.
Oxygen depletion sensors (ODS) and atmosphere sensing on flueless gas fires
How a thermocouple ODS shuts off gas, what it cannot establish, and why servicing is model-specific.
Space-Heater Flueing and Spillage Testing
Heater Types, Hearths and Carbon Monoxide Risk
Flueless heaters and the atmosphere-sensing device
Why flueless gas heaters depend on room ventilation and what the atmosphere-sensing device protects against.
Heater types and where carbon monoxide risk comes from
How open-flued, room-sealed and flueless heaters manage air and products, and where CO risk arises.
Use the appliance type to organise HTR1 revision
Identify whether the scenario describes an open-flued, room-sealed or flueless heater. Then connect that design to its air supply, combustion-product route and safety controls. Do not transfer a rule from one heater type to another just because both appliances heat a room.
Study the HTR1 guide alongside flue flow and spillage testing. For a ventilation calculation, first establish which rule applies to the stated appliance and location; the open-flued ventilation calculator explains the limits of its room calculation.
In-depth guides for this module
Longer walkthroughs that sit alongside the revision notes.
HTR1 revision guide: gas fires, space heaters and their flues
HTR1 revolves around fire types, the chimney behind them and proving the room and flue can live safely with the appliance.
Flame supervision device explained: what an FSD does and how it fails
An FSD detects flame and controls the gas supply if flame is not established or is lost.
More Gas modules
Every module has its own revision notes and question bank.