Hot-water heating systems can be classified by temperature and pressure.
Hot-water systems can be classified by operating temperature into three groups
- low temperature - LTW
- medium temperature - MTW
- high temperature - HTW
Low Temperature Hot-Water Heating System - LTW
- operates within a temperature of 250oF (121oC). The maximum allowable working pressure for a LTW system is usual 30 psi (2 bar).
- LTW systems are in general used for space heating in homes, residential buildings, offices, local distribution of district heating systems and similar.
Medium Temperature Hot-Water Heating System - MTW
- MTW systems operates at a temperature of 350oF (177oC) or less. The maximum allowable working pressure for a MTW system is usual 150 psi (10.5 bar)
- MTW systems are often used in large hot-water distribution systems like district heating, and in systems where process applications requires higher temperatures than achievable by LTW systems
High Temperature Hot-Water Heating System - HTW
- HTW systems operates at temperatures exceeding 350oF (177oC) or more. The maximum operating pressure for a HTW system is usual less than 300 psi (20.7 bar).
- HTW systems are used like MTW systems in large distribution and process application systems.