Hot Water Heating Systems Design

Introduction to Gravity Heating Systems and Forced Heating Systems

Gravity Circulating Heating System

In a hot water gravity heating system the circulation of water is a result of the density difference between hot water in the supply lines and cold water in the return lines.

Gravity Circulating Heating System

The hot water tends to flow upwards and cold water tends to flow downwards. The elevation of the supply and return lines are therefore important for proper functionality.

The low differential pressure in the gravity system requires increased pipes and valves dimensions. The gravity system has a relative low heating capacity due to low medium temperature in heating elements.

The gravity system is simple and limited to use in smaller hot water heating systems.

With a reversed return pipe the length of the supply and return pipes for all heating elements are more or less the same. This makes it easier to select proper piping dimension for balanced flow.

The expansion of water (4.7% from 0oC to 100oC) can be collected in an open expansion tank above the rest of the system or inside a closed pressurized tank close to the boiler and safety valves. In modern systems closed tanks are preferred.

Forced Circulation Heating System

In forced systems the circulation is forced by pumps.

Forced Circulation Heating System

Water is circulated by the pump regardless of temperature forces between hot and cold water. It is not necessary to be careful with piping elevations. Pipes, valves and heating elements, radiators and air heaters, can be downsized because of higher flow and higher mean temperatures.

Forced circulation systems are in general the only practical alternative for larger systems.

Related Topics

  • Heating - Heating systems - capacity and design of boilers, pipelines, heat exchangers, expansion systems and more

Related Documents

Tag Search

Search the Engineering ToolBox

- "Search is the most efficient way to navigate the Engineering ToolBox!"

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your SketchUp model with the Engineering ToolBox - SketchUp Extension/Plugin - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!

Translate the Engineering ToolBox!
About the Engineering ToolBox!

Support the ToolBox

If you find the Engineering ToolBox useful and want this website to be available tomorrow - and the days after tomorrow - enable ads or make a contribution!

Contribute to the Engineering ToolBox