Work package 3


Hydrogen appliance certification

Hydrogen appliances to be certified under GAR (Gas Appliance Regulation). These regulations will be aimed at providing guidance on the testing and certification of hydrogen gas appliances for notified bodies and appliance manufacturers.

BSI is developing an new PAS 4444 to be used primarily on the Hy4Heat programme but the aim is that it can form the basis for widescale standardisation of hydrogen-fuelled appliances. It will be a guide to be followed by appliance manufacturers regarding functionality safety, installation, operating and servicing requirements for their hydrogen fuelled and hydrogen/natural gas dual-fuelled or converted appliances, including: boilers; cookers; fires.

Hy4Heat conducted a survey of a number of Notified Bodies and Test Labs in the UK and Europe which indicated that hydrogen appliances could be certified under the current GAR and that the majority of Notified Bodies have the ability and capability to certify appliances. All those surveyed identified there were risks specifically relating to the testing of hydrogen appliances, this included:

  • Leakages will be harder to identify

  • Some design limits and choices may no longer be appropriate

  • Potential higher explosion risk

  • Additional laboratory safety devices may need to be added for hydrogen testing

  • Engineering practices may need to be adjusted; eg minimising voids, number of compression joints, etc

  • Flame monitoring solutions may require investigation for efficacy and reliability

  • There is a need for holistic assessment for risk, similar to natural gas or LPG

In conclusion there will be differences in how hydrogen appliances need to be tested.


Further information

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14 MAY 2019, PAS4444


PAS4444 will be the number for the hydrogen publicly available standard. BSI presented at our WP4 phase 2 kick off event on May 14th 2019. BSI’s slides can be found here.

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7 August 2018, Engagement event on domestic hydrogen appliance certification (WP3)

This session explains our planned approach to testing and certifying hydrogen appliances. There’s also the chance for networking with industry colleagues