The advantages of closed heating systems
Heating and cooling installation use water for the energy transfer because it’s the most cost
effective medium and most readily available, stable resource. Water expands when is heated, and
contracts (volume reduces) when cooled.
To accommodate expansion and contraction storage is
required. In general there are two types of system for accommodating thermal expansion, Sealed
systems (Closed) and Open vented systems.
- In an open vented system an open tank at the highest point of the installation is used to store the expanded fluid.
- In a closed system (pressurised/sealed) an expansion vessel is used to store the expanded fluid.
In this white paper we will discuss the advantages of a closed heating system.
Medium seized vessel water connection
In practice you will find expansion vessels with the water connection on bottom, and with the
connection on top. In this hite paper we want to expose what philosophies are behind the position
of the water connection.
This white paper discusses the difference between different types of vessels, the annual check and end-of-life disposal.
Expansion vessel in a solar installation
Like every closed system in which a liquid’s temperature changes, a solar installation also needs an
expansion vessel. However, there are some important differences between systems for solar and
central heating systems with regard to the location of the expansion vessel and the calculation of
the necessary capacity. This is due not only to the medium used but also the way in which solar
This white paper discusses the following:
- Solar boilers with a return flow.
- Overpressure solar boilers installations.
- Solar boiler installations with non-glazed collectors.
A half is more than one - The pre-pressure for an expansion vessel in the attic
There are many theories about the best pressure to fill a central heating installation with in relation to the pre-pressure of the expansion vessel and the final pressure in the system. An incorrectly set system can cause problems:
- If there is too much water in the system, the final pressure of the system will be reached too quickly. The safety valve then opens unnecessarily and the boiler malfunctions.
- Insufficient filling of the system can cause the expansion vessel to run dry when the system cools down. This causes the pressure to drop suddenly, which also results in the boiler malfunctioning. A vacuum may even arise, causing problems with air in the system.
In this white paper, we explain which pre-pressure is best for an attic installation.
Expansion vessels in
potable water systems
Potable water is a vital asset, everyone uses it. Although much of our planet is covered with water, we increasingly hear about impending shortages of clean potable water. One way to counteract some of the wastage of potable water is to use expansion vessels in potable water systems with calorifiers. When potable water is discharged from a calorifier through the pressure relief valve not only is this a waste of water, but energy is also wasted on heating this water.
In order to counteract this waste, an expansion vessel can be installed in a potable water system. However, if an expansion vessel is installed in a potable water system, this vessel will have to satisfy stringent requirements. Health risks must be avoided at all times.
Maintaining pressure in changeover systems
Changeover systems have made big advances in recent years, especially in installations that operate at low temperatures (heat pumps, cold/heat sources). The changeover from the supply of heat to cold and back is done by means of three-way valves. However, if one of the valves only switches over partly or not at all, then both systems become hydraulically connected to each other.
Expansion vessels or automats in the separate systems contain a certain amount of water depending on the pressure present. If the systems come into contact with each other, these pressures will level out, allowing water to flow from one system to the other. If the systems are then separated again, there may be too much water in one system and too little water in the other.