Heating engineers A–Z dictionary
UK trade reference · plain English
Safety: gas work must only be done by a Gas Safe registered engineer who is qualified for that type of appliance. Check their ID card or the Gas Safe Register. If you smell gas, leave the property and call the gas emergency number: 0800 111 999 in Great Britain or 0800 002 001 in Northern Ireland.
Heating work combines heat demand, distribution, controls and commissioning. A bigger appliance is not automatically the right answer to a cold room. Homeowners should describe symptoms and intended use, while tradespeople should define the diagnosis and work scope. This glossary separates common system terms without authorising gas or other specialist work. Product instructions, relevant standards and national building requirements still need checking for the actual installation.
This A–Z combines useful technical vocabulary with links to full references where the article meets our depth and sourcing checks. An unlinked definition is intentionally kept here rather than turned into a shallow standalone page. Read a quotation against its actual scope: a familiar word is not a complete specification.
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B
- Balancing
- Commissioning water distribution so the intended emitters receive suitable flow under design conditions. It is not a universal number of valve turns applied to every radiator.
E
- Emitter
- A component delivering heat to a space, such as a radiator or underfloor circuit. Output depends on design conditions rather than size alone.
F
- Flow temperature
- The water temperature leaving the heat source towards the system in this context. Its suitable value depends on the designed heat demand, emitters and appliance.
H
- Heat loss
- The rate of heat transfer from a building or room under stated conditions. A useful calculation records dimensions, construction and ventilation assumptions, not only floor area.
- Hydraulic separation
- An arrangement separating aspects of circuit flow where appropriate. It is a design decision, not an automatic improvement to every domestic heating installation.
I
- Inhibitor
- A specified treatment used in suitable water systems to help control corrosion. Correct compatibility and concentration need checking; adding a bottle does not diagnose every dirty system.
L
- Lockshield
- A radiator valve commonly used for setting flow in suitable arrangements. Its position and function differ from a normal user temperature control; adjustments should form part of proper commissioning.
W
- Weather compensation
- Control which adjusts a heating target in response to outdoor conditions within a suitable system. Setup and compatibility matter; it is not a guarantee of a particular saving.
Read the slang and site language dictionary · Browse related encyclopedia references
Sources and further reading
Linked article sources support the technical background; informal usage is editorial and varies by region. Full specification and legal requirements must be checked in the original.
- Baxi: operation and suitability
- Gas Safe Register: boiler guide
- www.hse.gov.uk/gas/domestic/faqownerocc.htm
- GOV.UK: Approved Document L
- GOV.UK: Approved Document G, hot-water safety
- Gas Safe Register: check and service differences
- HSE: appliances and landlord gas checks
- Energy Saving Trust: heating controls
Sources checked: 8 November 2026. General reference, not instructions for safety-critical DIY. National regulations and current standards must be checked for the project.
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