Smarter Heating & Hot Water

Flue gas analysis

A flue gas analysis is the analyser reading taken in the flue while the boiler is held at maximum or minimum rate. Engineers use it on a service to see whether combustion sits in the band the manufacturer publishes for that model.

The table is the hub reference list, with each reading in its own column. Empty cells were empty on that list. The brand tools check a reading against the limits already published for that brand. The instruction for the appliance in front of you is the one that counts. Opening the case and adjusting combustion is Gas Safe work.

Brand Model Case Fuel Rate CO/CO2 CO CO2 O2
Intergas ECO Open Maximum 8.6–9.6% 3.85–5.6%
Intergas ECO Open Minimum At least 8.4%, and not above the maximum-rate CO2 At least the maximum-rate O2, and not above 6.00%
Vaillant ecoTEC Plus Closed Natural gas Maximum < 0.0031 < 250 9.2 ± 1.0%
Vaillant ecoTEC Plus Open Natural gas Maximum < 0.0031 < 250 9.0 ± 1.0%
Worcester Bosch Greenstar i Natural gas Maximum and minimum < 0.004 < 350 ppm

The Intergas minimum-rate line is how the Intergas FGA tool reads that hub cell. The manual page the hub linked is the Combi Compact HRE installation manual, page 47.

Brand tools