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In February 2024, UL Standards & Engagement (UL Solutions) published the ninth edition of UL 795, the Standard for Commercial-Industrial Gas-Fired Package Boilers. This is now a bi-national Standard, ANSI/CAN/UL 795:2024 Standard for Commercial-Industrial Gas-Fired Package Boilers. It is the first North American Standard that offers manufacturers a path to certification for boilers using hydrogen blending up to 25%, setting a new benchmark for the industry. The scope of UL 795 UL 795 provides a certification path for hydrogen-natural gas blends, as well as other traditional fuel types within its scope. The new edition includes requirements for: Gas-fired package boilers. High-pressure steam and high-temperature water gas-fired boiler assemblies for the following fuel gases: natural gas, hydrogen-natural gas blends, LP-gas, LP-gas/air blends, and manufactured gas. Furnaces. Air heaters (United States only). The full Standard is available in the UL Standards Catalog. United States and Canadian requirements The need to address different certification paths for additional fuel sources and blends has come into focus As new technologies have diversified industrial and commercial boiler products over the years, the need to address different certification paths for additional fuel sources and blends has come into focus. The original edition of the UL 795 Standard, first published in 1952, has been modified many times over the years to accommodate changes to the industry and manufacturers’ needs. ANSI and SCC accreditation UL Standards & Engagement, the publisher of the UL 795 Standard, is accredited by the American National Standards Institute (ANSI) and the Standards Council of Canada (SCC) as a Standards Development Organization (SDO). This ninth edition of the Standard was developed in compliance with the requirements of ANSI and SCC for accreditation of a Standards Development Organization. This joint American National Standard and National Standard of Canada is based on, and now supersedes, the eighth edition of UL 795 and the first edition of ULC/ORD-C795-2021. How UL Solutions can help As a pioneer in the combustion industry, UL Solutions can review current boiler listings to check that they meet the new requirements or start a new quote. Leverage dedicated laboratory staff and their expertise in the boiler product category to help users find a path to testing and certification.

To address growing concerns about climate change and environmental sustainability, regulatory bodies, consumers and other stakeholders have placed an increased focus on the reduction of potent greenhouse gas emissions, such as traditional hydrofluorocarbon (HFC) refrigerants, to the atmosphere. In the U.S., several states have introduced measures curtailing the use of these products, including the California Air Resources Board’s (CARB’s) global warming potential (GWP) limit of 750, effective Jan. 1, 2023, for HVAC/R products and Jan. 1, 2024, for chillers, as well as additional requirements for refrigeration systems that went into effect in 2021.  lower-GWP refrigerant alternatives In response to these state regulations, manufacturers have been developing systems to use lower-GWP refrigerant alternatives. However, the alternatives to traditional HVAC/R refrigerants typically exhibit more flammable properties than refrigerants designated by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) as A1. A2L classification of refrigerants A2Ls are much more difficult to ignite and less flammable than A3 hydrocarbon refrigerants, such as propane The air conditioning and refrigeration industry has developed the A2L classification of refrigerants to overcome the challenges of using lower-GWP refrigerants. While having slightly higher flammability characteristics as compared to traditional A1 refrigerants, A2Ls are much more difficult to ignite and less flammable than A3 hydrocarbon refrigerants, such as propane. A bi-national (U.S. and Canada) consensus group was formed to update the product safety and application standards to allow for the safe use of these more environmentally friendly refrigerants within HVAC/R systems. Safety requirements UL 60335-2-40, the Standard for Household and Similar Electrical Appliances — Safety — Part 2-40: Particular Requirements for Electrical Heat Pumps, Air-Conditioners and Dehumidifiers, is a binational (U.S. and Canada) Standard based on the international IEC 60335-2-40 standard. UL 60335-2-40 establishes more conservative safety requirements than the IEC standard to reflect product usage in the North American market. Refrigerant leakage One of the risks associated with household electrical heat pumps, air conditioners, and dehumidifiers is refrigerant leakage. A refrigerant leak detection system that senses a loss of refrigerant pressure, a critical component in mitigating this risk, is required for all systems in the occupied space exceeding a prescribed refrigerant charge limit. Refrigerant leak detection systems are required to have both sensors and control logic electronics that activate the evaporator fan and use circulated air to quickly disperse and dilute refrigerant in the event of a leak to prevent the formation of refrigerant concentrations. UL 60335-2-40 UL 60335-2-40 requires appliances to be free of potential internal ignition sources to mitigate the risk of fire due to a leak UL 60335-2-40 also requires that refrigerant charge limits be based on the minimum occupied volume of the room where the equipment is expected to be used. This charge limit requirement also includes a safety factor of 4 to help ensure any leaked refrigerant is diluted to well below the lower flammability limit (LFL) based on room size. In addition, UL 60335-2-40 requires appliances to be free of potential internal ignition sources to mitigate the risk of fire due to a leak. UL 60335-2-40, fourth edition, updates On Dec. 15, 2022, UL Standards & Engagement published the fourth edition of UL 60335-2-40. Among other updates, the fourth edition refined requirements for leak detection systems to accommodate various methods, increase robustness and reliability, and account for deviation and drift over the system life cycle. Key updates for refrigeration detection systems Annex LL Annex LL is a normative element in UL 60335-2-40, pertinent to refrigerant detection systems for flammable refrigerants. The fourth edition contains a rewritten Annex LL that no longer references IEC 66079-29-1 for the conformity of flammable gas detectors. It establishes that when the refrigerant detection system senses a concentration of refrigerant gas that is 25% of the lower flammability limit (LFL) for that gas, the refrigerant detection system must initiate a system response to mitigate the potential hazard, as required by Clause 22 and Annex GG.  Carbon monoxide detector sensor requirements When the refrigerant detection system incorporates a group controller, it must comply with Annex 101.DVN When the refrigerant detection system incorporates a group controller, it must also comply with the requirements of Annex 101.DVN for informational technology equipment (ITE) cooling appliances. The fourth edition Annex LL also contains rewritten test methods based on current North American carbon monoxide detector sensor requirements, as specified in UL 2075, the Standard for Gas and Vapor Detectors and Sensors. Annex 101.DVM An informative Annex 101.DVM, a supplement to Annex LL, was revised to include requirements for deviation and drift over the lifetime of the refrigerant sensor. Annex 101.DVM now describes examples of acceptable paths of compliance for providing data and evidence substantiating the claimed life of a refrigerant sensor, as required by Clauses LL.7.2.DV of Annex LL.DV. Further updates to UL 60335-2-40 Requirements specified in the fourth edition of UL 60335-2-40 needed to be published by the end of 2022 to be included in the 2024 building code. At that time, however, discussions about refrigerant detection system requirements were not yet complete. Annex 101.DVM was added as informative to the fourth edition, but requirements were agreed upon as part of the review for Amendment 1 to the fourth edition of UL 60335-2-40. UL 60335-2-40, fourth edition, Certification Requirement Decisions The following requirements were published for Public Review on Feb. 24, 2023, and incorporated in the Certification Requirement Decisions (CRDs) published in early March 2023: UL 60335-2-40 as a replacement for Annex LL (dated March 8, 2023) UL 60335-2-89 as a replacement for Annex 101.DVP (dated Feb. 28, 2023) Additional clarification provided in CRDs was published in October 2023 for: UL 60335-2-40 as a replacement for Annex LL (dated Oct. 1, 2023) UL 60335-2-89 as a replacement for Annex 101.DVP (dated Oct. 9, 2023) The following updates were made between March and October 2023: 1) Clarification that all sequential tests do not need to be repeated for any alternate constructions or additional models (LL.1.3DV/101.DVP.1.3DV). 2) Specification that a longer time (60 minutes instead of five minutes) is allowed for the reaction to occur during specific tests: LL.7.2.1.2DV, item b LL.7.2.1.3DV, item b/101.DVP.7.2.1.2DV, item b 101.DVP.7.2.1.3DV, item b Importance of CRDs to system safety and reliability Because the third edition referenced IEC 60070-29-1, several points did not align with the UL 60335 The CRDs are crucial to enhancing the safety and reliability of refrigerant leak detection systems. Because the third edition referenced IEC 60070-29-1, several points did not align with the UL 60335 appliance Standard. Clearly defining the clean air test gas concentration parameters for all testing in LL2 without needing to reference Annex G improves the Standard’s usability.  Sensor requirement Defining the requirement that a sensor must be able to test a concentration of 25% of the LFL helps reduce the fire risk due to refrigerant leaks. Introducing drift and deviation allowances in LL7 helps evaluate the system’s reliability over its lifetime. Moreover, the CRDs incorporate what the working group and manufacturers have learned about this new technology to make UL 60335-2-40 a more robust and reliable Standard. Detection, mitigation, identification, and training Jim Dominik, managing member of Polaris Public Safety Solutions, shared his perspective on the CRDs’ importance, “The fire service has been concerned about A2L usage, and we worked hard to be part of the team and implement a safe solution." "Since the beginning, the fire service has asked for detection, mitigation, identification, and training. Lessening anything that could cause a reduction in detection and mitigation would decrease the overall safe operation of the equipment." Critical safety features "To date, we have no installed equipment, and I feel reducing any of the safety features would be concerning." "The current requirements proposed by UL Standards & Engagement in the latest Certification Requirement Decision following current UL Standards that have been proven to be safe is critical to the long-term safety of the equipment and potentially the people and environment.”

Heat pumps are not new technology. They have long been utilized in residential applications to improve the efficiency of HVAC systems, reducing overall energy costs. As a simple description, a heat pump is a mechanical refrigeration system that is engineered to operate in reverse mode, producing heating instead of cooling. technology drivers In recent years, there has been a trend of new and increased applications for this technology coming from two primary drivers: Advances in technology – Electronic controls, electronic refrigerant metering, and variable speed motors and compressors allow for more efficient and sophisticated systems. They can operate in a wider variety of climates and form factors. Energy efficiency, electrification, and decarbonization – Energy codes and regulations are driving many of these trends to reduce energy demands and CO2 emissions. In this context, electrification and decarbonization largely refer to replacing gas-fired appliances with electric heat pumps and the use of more energy-efficient appliances. A traditional electric resistance heating element converts almost 100% of the input electrical energy to heat. By leveraging the refrigeration cycle, a heat pump can move heat energy equivalent to 200% or more of the input electrical energy. Examples of growing heat pump applications Cold climate and geothermal heat pumps – These heat pumps can maintain their rated heating capacity at a lower outdoor ambient temperature. As a result, the geographical area where heat pumps are viable is expanding.   Variable refrigerant flow (VRF) heat pumps – These systems are optimal for buildings that simultaneously have heating and cooling loads. While one zone is being cooled, the heat removed from this zone can be utilized by another zone requiring heating.   Reverse operation, thermal battery storage, and heat recovery chillers – Air-to-water or water-to-water chillers can be engineered to operate in heating mode. Instead of rejecting waste heat from cooling, these systems can capture, store, and reutilize the heat removed from the building.   Heat pump water heaters – Includes tank-type storage water heaters as well as supplementary heaters, which pre-heat incoming water using waste heat from air conditioning systems.   Appliances such as dishwashers and clothes dryers – Any appliance that has traditionally produced heat via electric resistance heat has the potential to be a candidate for heat pump technology.   Air-to-water heat pumps for retrofit – These heat pumps are optimal for the renovation of existing spaces where water-heated radiators are installed. They can reach higher temperatures than the first heat pump generations, allowing retrofit without the need to renovate the full heat distribution system.   Codes and standards – The trend of expanded use of these mechanical systems coincides with the industry transition to refrigerants, which have lower Global Warming Potential (GWP). Model codes, installation standards, and product standards have been developed to address both the new technology and refrigerants to provide requirements for their safe use. It is more important now than ever to adopt and refer to the latest codes and standards.   ASHRAE installation standards – The following AHSRAE standards form the basis for installation requirements in coordination with model codes and product standards: ASHRAE 15 Safety Standard for Refrigeration Systems, ASHRAE 15.2 Safety Standard for Refrigeration Systems in Residential Applications, and ASHRAE 34 Designation and Safety Classification of Refrigerants.   UL Standards – The following UL Standards contain safety requirements for the appliances referenced above: UL 60335-2-40, the Standard for Household And Similar Electrical Appliances, UL 921, the Standard for Commercial Dishwashers, and UL 2158, the Standard for Electric Clothes Dryers.