✅ Safety groups - basic information, what are they and what are they used for?
Safety groups play a key role in controlling the operation of heating systems (CH) and domestic hot water systems (DHW), protecting them from threats such as overheating or blockages. They are used in various devices, such as heating boilers, (PHE) heat exchangers, radiators, boilers, water tanks, as well as in shower fittings and bathtubs.
A safety group is a type of measuring device that, in its own way, monitors the parameters of the heating system (preventing them from being exceeded). They are installed in CH or DHW systems to ensure safety and guarantee that certain pressure and temperature parameters are not exceeded (which would obviously be dangerous for our heating system). In this way, the safety group provides protection for the entire CH or DHW system.
Typically, CH / DHW safety groups must include elements that fulfill the tasks described above - that is, they prevent the dangerous levels of pressure and temperature from being exceeded. What are these elements?
Usually, a safety group consists of a safety valve, which in turn protects against the backflow of the medium (which could harm the system's efficiency and negatively affect the operation of pumps - the function of a check valve). Additionally, it also includes a pressure gauge, which is a device for measuring pressure.
The safety valve in such a group is responsible for discharging excess water - if there is a dangerous increase in pressure - to levels that could damage the CH or DHW system. Discharging a certain amount of water in such a situation can effectively relieve the system in terms of pressure, meaning the safety valve restores normal operating conditions in critical situations.
The functions and tasks of safety groups in both DHW and CH systems - regardless of the system they operate in - are similar. We will list them below, roughly in order of their importance from a safety perspective:
The safety group acts as a monitoring system and guardian that continuously and in real-time controls the water pressure in the system - and, if necessary, prevents the safe values from being exceeded. If the permissible pressure is exceeded - the safety group activates the safety valve, discharging some of the water and automatically restoring the system's balance.
The safety group in CH or DHW systems is designed to prevent the system from overheating - which, of course, is closely related to the previous point - as a significant increase in temperature also means a dangerous increase in pressure. If the safe temperature is exceeded, the safety group will act preventively by opening the safety valve.
Water backflow is a harmful phenomenon in itself - in all heating systems. Proper circulation always means greater system efficiency and saves circulation pumps (both additional ones and those that are standard equipment in CH boilers). The safety group prevents water backflow thanks to the presence of a check valve. This is a small device that fulfills this very function.
The formation of negative pressure is also an undesirable phenomenon. In the event of the safety valve opening, negative pressure could cause air or water to be sucked back into the system. This is a dangerous phenomenon, but safety groups have mechanisms to protect against it.
The appearance of safety groups may vary depending on the manufacturer. Popular models include those where all elements are mounted on a bracket that is attached to the wall, but the design can also be completely different. It is important that all elements that contribute to the system's safety are included. There are also models that come with factory insulation, in line with the current trend of avoiding heat loss even on small components.
When it comes to central heating systems - for the safety group to function properly, it is usually installed at the connection to the heat source, typically the heating boiler. The safety group and valve always operate automatically, without the need for manual control, and the signal for action is triggered by the laws of physics - when the permissible levels of temperature and pressure are exceeded.
An important element that we haven't mentioned yet, which allows for the discharge of excess water, is the drain pipe, which is connected to the sewage system.
On the other hand, in domestic hot water systems, the safety group is installed closer to the DHW tank, of course, on the supply side. The principle of operation and construction of the group is essentially the same. The tasks to be fulfilled are also similar. In DHW systems, it is very important to prevent water from flowing back into the tank - the water in the tank is protected, and often systems for automatic heating against Legionella are in place. Backflow - and then reintroducing the water into the tank - could also lead to contamination.
_____________
We invite you to check out Nordic Tec's offerings in the following areas:
How to choose a heat exchanger for a gas boiler?
Which plate heat exchanger for a 20 kW boiler?
Cleaning and maintaining the heat exchanger
Mixing valves, three-way, four-way - what exactly are they?
How to choose a pellet stove for your home?
Leave a comment