As mentioned in Part 1, we have decided to investigate purchasing and having installed a tankless water heater.由于部分提到，在一，我们已决定进行调查，购买和拥有tankless安装了热水器。 However, if we do it must meet four conditions:不过，如果我们这样做必须符合四个条件：
Natural gas as the energy source天然气作为能源来源
Sufficiently sized to meet our hot water needs充分大中，以满足我们的热水需求
Product manufactured by and installed by reputable companies to reduce the risk of unsatisfactory product performance and/or installation, […]产品的制造和安装的有信誉的公司，以减少风险，不理想的产品性能和/或安装， [ … … ]
