Condensing boiler
According to the Non-domestic building services compliance guide, 2013 edition, published by HM Government, a condensing boiler is: '… a boiler that offers a high energy efficiency by recovering heat from the flue gases. This is achieved by increasing the heat exchanger surface area, which recovers extra sensible heat whenever the boiler fires. The boiler becomes even more efficient when system water temperatures are low because the larger heat exchanger area promotes condensation, allowing much of the latent heat to be recaptured. Standard losses (when the boiler is not firing) are low, and part load performance is very good. In multiple-boiler systems, condensing boilers can be used as the lead boiler.'
The Illustrated Guide to Mechanical Building Services, Third Edition (BG 31/2017), by David Bleicher, published by BSRIA in 2017, states in relation to condensing boilers: ‘The flue gases (otherwise known as products of combustion) from a conventional boiler consist primarily of carbon dioxide (CO2) and water vapour, plus other gases such as oxides of nitrogen. The water vapour holds a significant amount of energy, known as latent heat. In a condensing boiler, the flue gases are cooled before being discharged, so the water vapour condenses (turns into liquid water). The latent heat released is used to preheat water returning to the boiler, and so condensing boilers are more energy-efficient than conventional ones. In order for this condensing process to work, the return water must be below a certain temperature. For this reason, and also that the flue gases are cooler and less buoyant, condensing boilers can’t always directly replace non-condensing boilers in existing buildings.’
[edit] Related articles on Designing Buildings
- Balanced flue appliance.
- Biomass boiler.
- Boiler efficiency.
- Carbon monoxide detector.
- CHP boiler.
- Coefficient of Performance CoP.
- Combustion appliance.
- Domestic building services compliance guide.
- Domestic micro-generation.
- Energy related products regulations.
- Fluepipe.
- Gross calorific value.
- Heat generator.
- Heat interface units.
- Heat pump.
- Industrial gas boilers market 2020.
- Non-domestic building services compliance guide.
- Types of domestic boiler
Featured articles and news
Boiler Upgrade Scheme and certifications consultation
Summary of government consultation which closes 11 June 2025.
Deputy editor of AT, Tim Fraser, discusses the newly formed society with its current chair, Chris Halligan MCIAT.
Barratt Lo-E passivhaus standard homes planned enmasse
With an initial 728 Lo-E homes across two sites and many more planned for the future.
Government urged to uphold Warm Homes commitment
ECA and industry bodies write to Government concerning its 13.2 billion Warm Homes manifesto commitment.
Places of Worship in Britain and Ireland, 1929-1990. Book review.
The emancipation of women in art.
CIOB Construction Manager of the Year 2025
Just one of the winners at the CIOB Awards 2025.
Call for independent National Grenfell oversight mechanism
MHCLG share findings of Building Safety Inquiry in letter to Secretary of State and Minister for Building Safety.
The Architectural Technology Awards
AT Awards now open for this the sixth decade of CIAT.
50th Golden anniversary ECA Edmundson awards
Deadline for submissions Friday 30 May 2025.
The benefits of precast, off-site foundation systems
Top ten benefits of this notable innovation.
Encouraging individuals to take action saving water at home, work, and in their communities.
Takes a community to support mental health and wellbeing
The why of becoming a Mental Health Instructor explained.
Mental health awareness week 13-18 May
The theme is communities, they can provide a sense of belonging, safety, support in hard times, and a sense purpose.
Mental health support on the rise but workers still struggling
CIOB Understanding Mental Health in the Built Environment 2025 shows.
Design and construction material libraries
Material, sample, product or detail libraries a key component of any architectural design practice.
Construction Products Reform Green Paper and Consultation
Still time to respond as consultation closes on 21 May 2025.
Resilient façade systems for smog reduction in Shanghai
A technical approach using computer simulation and analysis of solar radiation, wind patterns, and ventilation.