在美国，50个最大的大都市地区中，62%的所有住房单元使用燃气热水器（如果不包括佛罗里达州，则为67%），而在每年为这些家庭销售的约400万台燃气储水式热水器中，只有5%的销量达到或高于EnergyStar®0.67统一能源系数（UEF）的水平。这在加利福尼亚州更为明显，那里大约75%的家庭使用天然气供暖，900万台的安装基数，美国四分之一的燃气热水器，95%的家庭使用0.62 UEF的最低允许效率产品。更高效率选项的可用性不是问题，存储产品的可用性最高为0.88 UEF，无罐产品的可用性最高为0.97 UEF。相反，这反映了广泛部署高效热水产品的历史性挑战，在这种情况下，低成本天然气和较高的设备和安装成本的结合限制了使用，留下了提高能效和减少排放的巨大潜力。 为了解决这一潜在问题，作者描述了一种用于住宅应用的集成燃气热泵热水器（GHPWH），该热水器设计用于直接改造，与传统基准相比，可将能耗和排放降低50%或更高。GHPWH基于使用氨水工作对的直接燃烧单效蒸汽吸收循环，并结合内部热回收，以实现预计的1.2-1.3 UEF，具体取决于使用模式。虽然之前的出版物中描述了GHPWH的设计和开发，但作者在这里概述了南加州扩大示范的结果，包括安装效率与测量基线、安装和运行挑战，以及安装人员和宿主现场的定性输入。此外，作者还报告了一项模拟研究，以量化GHPWH安装在半封闭式空调系统中时对家庭HVAC系统的影响- 有条件的或有条件的空间。引用:佛罗里达州奥兰多2020年冬季会议论文

In the U.S., 62% of all housing units in the 50 largest metropolitan areas are served by gas-fired water heaters (67% if Florida is excluded), and for the ~4 million gas-fired storage water heaters sold each year to serve these homes only 5% sold are at or above the EnergyStar ® level of 0.67 Uniform Energy Factor (UEF). This is even more pronounced in California where natural gas fuels water heating in approximately 75% of homes, an installed base of 9 million units, one in four gas-fired water heaters in the U.S., and 95% of homes are served by minimum allowable efficiency products of 0.62 UEF. The availability of higher efficiency options is not the issue, with products available up to 0.88 UEF for storage products and 0.97 UEF for tankless products. Instead, this reflects a historic challenge to broadly deploy high-efficiency water heating products, where the combination of lower cost natural gas and higher equipment and installation costs have limited uptake, leaving a large potential for energy efficiency and emissions reductions.To address this potential, the authors describe an integrated gas-fired heat pump water heater (GHPWH) for residential applications, designed for a direct retrofit and to reduce energy consumption and emissions by 50% or greater over conventional baseline. The GHPWH is based on a direct-fired single-effect vapor absorption cycle using the ammonia-water working pair and incorporates internal heat recovery to achieve a projected 1.2-1.3 UEF, depending on usage patterns. While the design and development of this GHPWH is described in prior publications, here the authors provide an overview of results from an expanded demonstration in Southern California, including as-installed efficiencies versus measured baseline, installation and operating challenges, and qualitative input from installers and the host sites. Additionally, the authors report on a simulation study to quantify the impact of the GHPWH on the home’s HVAC system when installed in a semi-conditioned or conditioned space.