NOTE: The PAS does not cover the prevention of flash back from hydrogen applications into gas carcasses containing air/hydrogen mixtures.

What is PAS 4444:2020+A1:2021 about?

The Department for Business, Energy and Industrial Strategy (BEIS) has set up the Hy4Heat Research and Innovation Programme to explore a transition from natural gas to hydrogen for cooking and heating in the UK.

The programme is intended to establish if it is technically possible, safe and convenient to use zero-carbon hydrogen gas in residential and commercial buildings and gas appliances. This will enable the UK Government to determine whether to proceed to a community trial phase.

PAS PAS 4444:2020+A1:2021 has been written primarily to support this programme but could also form the basis for wide-scale standardization of hydrogen-fuelled appliances by providing principles for manufacturers regarding the safety and functionality of hydrogen-fuelled and hydrogen/natural gas dual-fuelled or converted appliances including: boilers, cookers and fires.

Who is PAS 4444:2020+A1:2021 for?

Manufacturers of hydrogen-fired gas appliances
Manufacturers of gas appliances that are designed to be converted to use hydrogen
Notified Bodies and other appliance test houses

Why should you use PAS 4444:2020+A1:2021?

This document gives guidance on the development and construction of hydrogen-fired gas appliances, which are either purpose-built to use hydrogen or are designed to be converted to use hydrogen.

It covers the functional specification of the appliance, including specific advice on the demonstration of safety, including worst case conditions to stress the appliance in excess of that it is likely to experience in normal service.

It also covers the setting of limit (upper and lower) hydrogen supply pressures and limit voltages. It discusses the possible arrangement of fittings and devices acknowledging the application to hydrogen fired appliances.

The PAS also covers tests regarding both delayed ignition and unintended ignition of accumulated gas (which has leaked from the gas circuit) within the case of the appliance and/or its flue. It covers advice on manufacturer’s instructions regarding installation of such appliances (including fluing) and their servicing requirements.

NOTE: PAS 4444:2020+A1:2021 is intended to be used as a supplement to existing standards and generally assumes that any default performance requirements (for example, noise or pressure rating) align with those of an equivalent second family gas appliance unless specifically stated otherwise.

We are keen to receive feedback on PAS 4444:2020+A1:2021 from its users on its implementation to inform any future revisions. In order to gather this live user feedback on the PAS, BSI is also hosting the text of PAS 4444 online for all its purchasers for six months after publication, and invite purchasers of the PAS to comment on the PAS during this time period. Details on how to participate in providing this live feedback are provided inside the PAS.

PAS 4444:2020+A1:2021

Hydrogen-fired gas appliances. Guide

Current

Published:

31 Dec 2021