在过去十年中，燃气热水器越来越受欢迎，与标准储水式热水器相比，全家式无水箱热水器由于其效率高、“无穷无尽热水”的营销，以及公用事业和政府激励计划，其市场份额不断增加。随着受欢迎程度的激增，人们对其性能局限性有了更好的理解，因为在最近的几项研究中，在很大程度上是由于最低热水抽取率要求和启动顺序延迟，导致了其在交付效率方面的缺陷。 虽然这些缺陷已被充分描述，以促使修改建筑规范，但从分析角度进行修改仍然是一个挑战。为了更好地模拟全屋无水箱热水器的性能，基于现有的鲁棒单节点模型，作者描述了几个带有实验室测试电池的单元，重点关注短期性能和间歇性行为。现有模型虽然完整地描述了作为换热器的稳态和瞬态传热行为，但可能需要进一步完善，因此一些输入可能对试验条件（例如:。 G热容量）以及无水箱热水器控制的一些影响，例如启动加热延迟。引用:德克萨斯州达拉斯ASHRAE Transactions第119卷第1部分。

Gaining popularity over the past decade for gas-fired water heating, whole-house tankless water heaters have enjoyed increasing market share due to their high efficiency, relative to standard storage water heaters, the marketing of "endless hot water," and utility and government incentive programs. With this surge in popularity has come a better understanding of their performance limitations with deficiencies in the deliveredversus- rated efficiency characterized by several recent studies, due in large part to the minimum hot water draw rate requirements and startup sequence delays. While these deficiencies have been characterized sufficiently to prompt the modification of building codes, it remains a challenge to do so analytically. To better simulate the performance of whole-house tankless water heaters, building on an existing robust single node model, the authors have characterized several units with a laboratory test battery, focusing on short-term performance and intermittent behavior. This existing model, while complete in describing the steady-state and transient heat transfer behavior as a heat exchanger, may require additional refinement whereby some inputs may have sensitivity to test conditions (e.g,. thermal capacitance) and some impacts of tankless water heater controls are not captured, such as startup heating delays.