PAS 4444:2020+A2:2026

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What is PAS 4444:2020+A2:2026, Hydrogen-fired gas appliances – Guide about? 

PAS 4444:2020+A2:2026 gives guidance on the development and construction of hydrogen-fired gas appliances. It sets out functional safety, installation, operation and servicing requirements for hydrogen‑fired, hydrogen/natural‑gas dual‑fired, and converted appliances including boilers, cookers and fires.

PAS 4444+A2:2026 supersedes PAS 4444+A1:2021. This amendment addresses the issue of ignition into the hydrogen supply pipe. It also aligns with emerging European Committee for Standardization (CEN) standards. This will support the H100 Fife trial, which will test the feasibility of replacing natural gas with hydrogen for cooking and heating in up to 300 homes.  
 

Who is PAS 4444:2020+A2:2026, Hydrogen-fired gas appliances – Guide for?

• Appliance manufacturers: Standards assist in the manufacturing and safe operating requirements of the hydrogen-fired/ready appliances, helping to reduce risks.
• Testing and certification bodies: Standards assist in making a ‘judgement call’ for the bodies to certify with confidence. It provides uniform expectations for assessment criteria aligned with safe outcomes.
• Installers: Standards demystify conversion and installation procedures, reduce their risk, and improve competence in installing hydrogen-fired/ready appliances.
• Gas network operators (GNOs) and utilities: Standards enhance compatibility of appliances for hydrogen trials (such as H100 Fife) while also improving reliability and safety for integrating H2 into utilities networks.
• Regulators and policymakers: Standards improve technical endorsement for policy development.  
  

What does PAS 4444:2020+A2:2026, Hydrogen-fired gas appliances – Guide cover?

PAS 4444:2020+A2:2026 covers appliance development and construction, functional specifications, safety demonstration, reasonably foreseeable conditions of stress, voltage limits, and hydrogen supply pressure limits. 

Why should you use PAS 4444:2020+A2:2026, Hydrogen-fired gas appliances – Guide?

Hydrogen has been considered as a potential low-carbon alternative fuel to natural gas. PAS 4444:2020+A2:2026 supports manufacturers of hydrogen-fired products in creating and/or converting appliances to use hydrogen.

What has changed?

This second amendment updates three areas of PAS 4444: prevention of ignition into the hydrogen supply pipe, supply test pressures, and alignment with new standards.