Boilers transfer energy to liquids

A boiler transfers energy from fuel, electricity or another energy source, to a fluid that is used outside the boiler. The fluid, which is usually water in various forms, is both pressurised and hot. If the boiler starts to leak, there is a high risk of serious burns. There are also hot oil boilers, where a special heat-resistant oil is heated. The oil can then be used in a heat exchanger to heat, for example, a drying process.

High risks if boiler is mismanaged

There are great risks in using a boiler if it is not safely managed and monitored. Because a boiler is pressurised and hot, both parts and hot liquid can fly out if a boiler cracks or bursts. As an employer, you must therefore ensure that your boilers are kept in good condition and are safe to use.

Before you start to use a boiler

If your boiler is in class A or B according to the Swedish Work Environment Authority's provisions and general guidelines (AFS 2023:11) on work equipment and personal protective equipment - safe use, Chapter 9, it must be inspected by an inspection body before you can pressurise it.

You have pressurised your boiler when you have started the boiler's circulation pump or water feed pump. The inspection body must also have made an assessment of how the boiler should be monitored before you put the boiler into operation. A boiler is in operation when energy is transferred to the water, or to the oil if it is a hot oil boiler.

Examples of class A and B boilers

Some examples of boilers that belong in class A are hot water boilers, steam boilers or hot oil boilers. Boilers that belong in class B are often called hot water boilers, but they should not be confused with water heaters for domestic hot water.

Read more about control of pressurised devices in classes A and B.

Control of pressurised devices

Competence and procedures for monitoring boilers

A boiler operator tasked with monitoring a Class A or B boiler needs to have the right skills to perform the task safely.
The boiler operator should be familiar with the boiler's safety system and know how to respond to safety-related alarms. As an employer, you must document the assignment as a supervising boiler operator. It must be clearly stated which tasks are included in the assignment.

You as an employer must ensure through documented procedures that

• the boiler is started up with constant monitoring
• the boiler is monitored as stated in the report from the inspection body
• in the event of an alarm, the boiler operator can arrive on site within the response time set by the inspection body.

Monitoring, alarms and response

When the accredited inspection body that you hire for the recurring inspection performs operational tests on the boiler, they also make an assessment of how the boiler should be monitored. Some boilers are only used with constant supervision. The operator can then address situations that arise before they become dangerous.

If you want to use your boiler with periodic monitoring, it must have equipment that can prevent

• the fluid level becoming too low
• temperature too high
• insufficient flow through the boiler.

The certificate from the inspection body governs the monitoring

The certificate issued by the inspection body after the operational test states how you should monitor your boiler. It also specifies the response time for a boiler operator in case of an alarm from the boiler. You must monitor the boiler as often as the inspection body has stated in the certificate, and not at longer intervals than what is stated there.