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Commissioning Gas Boilers – Benefits of New Regulations Mike Murley, Product Manager, Testo Limited February 2012

Installing and commissioning a gas boiler is about to become safer, with additional peace of mind for the consumer and the commissioning engineer. From April 2013 boiler manufacturers will be recommending that the CO level in the flue gas is measured and recorded when a boiler is commissioned. From April 2014 this measurement becomes mandatory. Practically this means that commissioning engineers will be required to measure the CO and the CO/CO2 combustion ratio using an electronic Flue Gas Analyser. The measurements must be recorded on the commissioning document, such as the HHIC Benchmark Commissioning Checklist, and will become a condition of warranty.

New flowchart This new regulation has been formulated and agreed by the Heating and Hotwater Industry Council (HHIC) in consultation with the boiler manufacturers, the HSE, Gas Safe Register, CoGDEM, Energy & Utility Skills, UKLPG as well as major installers. HHIC has established a new CO testing flowchart which will be replicated in boiler manufacturer instructions. The flowchart includes the limits that the installer should be looking for, which are a maximum of 350ppm CO measured in the flue and a combustion ratio of less than 0.0040. Importantly the flowchart also highlights that if the boiler is working outside of the recommended limits of CO combustion ratio then the appliance should be turned off and the installer should call the appliance manufacturer’s technical helpline. This removes the onus on the installer to adjust the boiler.

How does this benefit the installer? All boilers are manufactured and tested to high standards and leave the factory set to ensure very low CO emissions. In the past the rationale was that further CO tests at commissioning were not required, and mostly this was true. But the problem was the rare occasion when the commissioning resulted in non-ideal combustion. The new regulation protects the installer from inadvertently leaving a new installation with incorrect combustion or even dangerous carbon monoxide levels. Many installers already use a FGA as their standard code of practice for commissioning new boilers. Arguably the onus has been on these installers to make adjustments to achieve acceptable combustion ratio and CO if it was not reading the correct level. The new recommendation and associated flowchart gives the installer a clear framework to get advice from the boiler manufacturers’ technical helplines.

Implications for the Flue Gas Analyser FGAs have evolved into multi-purpose instruments capable of measuring pressure and temperature as well as flue gases. These measurements enable a full range of tests including tightness and let by, differential temperature, efficiency, gas leak detection, gas rating and so on. Whilst many engineers appreciate and use all these features, the commissioning engineer often just needs an analyser which can quickly give him the necessary flue gas measurements. In the context of the new regulations and flow chart this means an analyser which can display the O2 or CO2 at the air inlet, and the CO ppm and combustion ratio in the flue. The new Testo 310 flue gas analyser is one of a new breed of analysers which meet this need for simplified operation and address the need for an entry level product at remarkable value. 1

Commissioning Gas Boilers – Benefits of New Regulations Mike Murley, Product Manager, Testo Limited February 2012

Availability With these new regulations the FGA becomes an even more essential part of the heating engineers’ toolkit. Installations cannot be completed and signed off without the analyser. With the need to have annual calibrations this can be problematic. Analyser manufacturers have certainly stepped up to the mark to improve turn round times to ensure minimal disruption to contractor’s business. Testo has significantly improved turnaround times to just a few days through the introduction of new processes and additional staff and Testo also offers Express Service options or even Same Day and On Site calibration. New Fixed Price Servicing which includes calibration and any repairs has helped to streamline the process by waiving the need to quote and then seek authority to proceed with repairs. Most manufacturers also work hand in hand with merchants to provide convenient drop off and collection of analysers. As well as using the merchant network Testo has also approved an independent network of qualified service centres to give customers the choice of where they chose to get their analyser calibrated. So in summary, the new regulations will benefit the industry and the consumer. And although it means all commissioning engineers will need to use a FGA, the industry has developed products and services which don’t break the bank. For details of Testo visit


Commissioning of Gas Boilers - Benefits of New Regulations  

Commissioning of Gas Boilers - Benefits of New Regulations 2013