Hot-Water Heating Systems - Classification

Hot-water systems can be classified by operating temperature into three groups

• low temperature - LTW
• medium temperature - MTW
• high temperature - HTW

where

Low Temperature Hot-Water Heating System - LTW

• operates within a temperature of 250 ^oF (121 ^oC). 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 350 ^oF (177 ^oC) 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 350 ^oF (177 ^oC) 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.