ETC系统比FPC系统便宜. They perform better in colder regions and avoid freezing problem during sub-zero temperature. FPC based systems also perform well with anti-freeze solution at sub zero temperature but their cost increases. 在其他地区，两者的表现同样出色. 利用热虹吸原理工作的系统简单且相对便宜. 它们适用于国内和小型机构应用, 前提是水质良好，氯含量不高. Forced circulation systems are generally preferred in industries or large establishments. 在水坚硬且氯含量较高的地方, 如果正在安装基于FPC的系统, it must be with heat exchanger as it will avoid scale deposition in copper tubes of solar collectors which can block the flow of water as well reduce its thermal
表演。. ETC based systems will not block the flow of water but its 表演。 may go down due to deposition of salt contents on inner surface of glass tubes, 哪些可以一年左右清洗一次.