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Hydronic Heating Systems

 

Hydronic heating systems use hot water to heat buildings and spaces.

A hydronic heating system requires a heat source to be connected to heating elements by using pipes, valves, fittings, and a circulation pump.

1. Heat Source

 

A core component of a hydronic heating system is the heat source. 

The heat source takes cold (or warm) water and generates hot water.

The most common heat sources used in hydronic heating systems are:

1 - Gas Fired or Electric Boiler - the traditional choice in the industry

2 - Ground Source (Geothermal) Heat Pump - a newer technology increasing in popularity because they use natural sources of heat instead of fossil fuels

 

In H2X's hydronic heating design software, you can select any type of heat source

that your project requires and set the relevant feed and return temperatures (Delta T).

2. Heating Elements

 

To heat up a building, you need to transfer energy (heat) from the hot water to the space.

The most common heating elements that are used to do this are:

1 - Radiators - a cost effective installation that has higher operating costs due to their inefficiency

2 - Underfloor Heating Systems - a more expensive installation that provides better efficiency and more comfort for the end user

In H2X's hydronic heating design software, you can create any radiator or underfloor heating element for your design, specify the kW rating, and automatically receive flow rates and pipe sizes.

 

3. Pipe Layout

To operate correctly, hot water is circulated to each heating element through pipes.

There are usually two pipes that run together, these pipes are known as the 'feed' and 'return'. 

The 'feed' water (∼ 70 °C) pipe supplies the water from the heat source to the heating elements.

The 'return' water (∼ 50 °C) pipe is the water returning from the heating element to the heat source.

As the feed water loses heat through the pipes and heating element, the return pipework will circulate it back to the heat source to be re-heated and to follow the same process again. 

 

In H2X's hydronic heating design software, it is easy to draw the pipework layout.

You also choose the pipe material and set the system's maximum velocity (∼ 1 m/s)

4. Hot Water Circulation Pump

The hot water circulation pump is a critical part of the hydronic heating system. It is responsible for maintaining the system temperature by moving water from the heat source, to the heating element, and back to the heat source.

The duty of the hot water circulation pump is difficult to calculate due to the number of variables involved. A list of the variables are:

 

1 - Flow Rate

The factors that contribute to the flow rate calculation are:

  • The pipe sizes

  • The pipe insulation

  • The delta T of the system

  • The heating elements

  • The ambient air temperature

  • The air speed in the building

2 - Pressure

 

The factors that contribute to the pressure drop calculation are:

  • Friction loss through the pipes

  • Friction loss through the fittings

  • Friction loss through valves

  • Friction loss through heating elements

Note that the pressure calculation is only to the most disadvantaged heating element. 

In H2X's hydronic heating design software, hot water circulation pump duty is automatically calculated based on all of the factors noted above.

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How to Design a Hydronic Heating System Using H2X