What is a boiler flue?
Dominic Bowkett
Last Update 3 days ago
Boiler flues are critical components of a heating system, responsible for safely expelling combustion by-products, such as carbon monoxide, carbon dioxide, and water vapour, from the property to the outside atmosphere. Their correct identification and assessment are crucial for determining a dwelling's ventilation rate and overall energy efficiency.
In the context of RdSAP 10 and Version 12 of the conventions, effective from 1st May 2025, boiler flues are specifically categorised and accounted for. As outlined in the conventions (specifically in relation to the "Boiler Flues" count within the ventilation section), boiler flues are those specifically connected to a solid fuel boiler which is located within the heated envelope.
Important Clarification for Assessors: It is crucial to note that the count for "boiler flues" in RdSAP specifically pertains to solid fuel boilers. If a dwelling has a different type of boiler, such as a fan-flued combi boiler (which typically uses gas or oil), this should not be included in the count for "boiler flues" and should be recorded as 0 in this specific category.
The assessment's count for these flues includes solid fuel boilers that are situated within the heated envelope of the dwelling being assessed.
It is important for assessors to distinguish boiler flues from other types of flues, such as open chimneys, open flues, closed flues or flues associated with other room heaters (RdSAP Convention 9.01). The specific classification ensures that the appropriate ventilation assumptions are applied within the energy assessment methodology, contributing to a precise Energy Performance Certificate (EPC).
When conducting an assessment, qualified assessors should:
Identify the fuel type: Confirm that the boiler is indeed a solid fuel boiler.
Locate the flue: Visually identify the flue pipe or system connected to the boiler.
Verify location: Confirm that the solid fuel boiler is within the heated area of the dwelling.
Document: Record the presence of the boiler flue as per the RdSAP 10 conventions, ensuring all relevant data inputs are completed accurately.
By meticulously identifying and recording boiler flues according to the latest conventions, assessors contribute to the robustness and accuracy of energy assessments, providing homeowners and occupants with reliable information regarding their property's energy performance.