|New Guidance Note from Gas Safe Register|
Following a number of CO incidents relating to condensing boilers with air/gas ratio control valves Gas Safe Register in conjunction with the HHIC have issued a new guidance note to clarify the action levels at measured CO/CO2 ratios. All installers should read Technical Bulletin 126 on the Gas Safe Register website.
The crux of the Guidance Note states the following:
Boilers fitted with an air/gas ratio mixing valve where the CO/CO2 ratio exceeds 0.008 are classified as "Immediately Dangerous"
Boilers fitted with an air/gas ratio mixing valve where the CO/CO2 ratio exceeds 0.004 but does not exceed 0.008 are classified as "At Risk". (Unless the manufacturer has specified a ratio lower than 0.004)
It is also proposed that future revisions to BS7967 and GIUSP will also adopt 0.004 as the action level for all boilers fitted with a gas/air ratio valve.
Some boiler manufacturers already define safe combustion levels for their boilers and recommend that a combustion check is performed when commissioning.
The contact details for all boiler manufactured who are members of the HHIC are given in the appendix of Technical Bulletin 126.