Photo by thanyapatm on Envato
Author: Federico Re Ferrè
Key Points of the Article
- The gas-fired heating plants are subject to specific fire safety regulations, in particular Ministerial Decree of November 8, 2019, which sets forth requirements based on thermal capacity.
- Below 35 kW , no fire safety regulations apply; however, above this threshold, technical measures to ensure safety become mandatory.
- There are requirements for minimum height, ventilation, fire resistance of structures and the presence of gas detection systems.
- Access must be through an REI hallway, and the door must open outward and meet certain minimum dimensions and be made of fire-resistant materials.
- The premises must ensure fire compartmentalization and, if necessary, can be adapted by installing drop ceilings, false walls, and column encasements.
Heating plants are classified as technical rooms that are particularly prone to fire risk due to the presence of combustion chambers; for this reason, there are regulatory measures in place to ensure safety in the event of a fire.
The relevant regulation is the consolidated text of the Ministerial Decree of November 8, 2019, which establishes the technical rules for fire prevention in heating plants fueled by gaseous fuels.
When a Premises Becomes a Heating Plant: The 35-kW Threshold
The total heat output in a single room is the key factor in determining what measures to take. The first threshold to consider is 35 kW: below this threshold, the room is not classified as a boiler room, and therefore fire safety upgrades are not required.
This is the most common scenario for homes equipped with their own independent boiler, typically around 30 kW, which can be installed indoors (such as in the kitchen, basement, or garage, regardless of whether it is a heated room or not) or outdoors (on the balcony or along the perimeter of the building on the ground floor) without any particular restrictions.
It should be noted that the power calculation must be performed for each installation room and not for each hydraulic circuit: two hydraulically separate 30-kW boilers (one for heating and one for domestic hot water or a heating circuit separate from the first), if installed in a single room, constitute a total power of 60 kW and require compliance with fire safety requirements; conversely, two 30-kW boilers supplying the same hydraulic circuit but located in two separate areas (for example, one on the roof and one in a basement) do not requirecompliance with fire safety requirements.
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Fire Safety Requirements for Premises with a Power Rating Exceeding 35 kW
If the power exceeds 35 kW in the same room, the provisions of the aforementioned Ministerial Decree apply. A heating plant cannot be located more than 10 m below the reference floor and must have an exterior wall whose length is at least 15% of the perimeter; this requirement mandates that furnaces be located on the periphery of the building so that they can be easily accessed in the event of an emergency.
If the length of the exterior wall is less than 15%, a gas leak detection system must be installed that controls a manually resettable solenoid valve and optical and acoustic alarm devices.
Fire-Resistant Compartments and Structural Modifications
The heating plant, which is integrated into the building’s structure, must be designed as a fire compartment to preventthe fire from spreading to the rest of the building; for this reason, the walls and ceilings must have a fire resistance rating commensurate with the installed thermal capacity.
IIn the event of a fire , the heating plant must not collapse while awaiting emergency responders; this is why the columns must also be fire-resistant. If these characteristics are not present, a heating plant can be brought up to code by installing REI/EI partition walls and false ceilings and by encasing the existing columns .
| Thermal capacity | Load-bearing structures (columns) | Partition elements (walls, ceilings) | ||
| Fire Resistance | Reaction to fire | Fire resistance | Fire behavior | |
| Less than 116 kW | R ≥ 60 | 0 (Italian)
A1 (European) |
REI/EI ≥ 60 | 0 (Italian)
A1 (European) |
| Greater than 116 kW | R ≥ 120 | REI/EI ≥ 120 | ||
Minimum height based on heating capacity
The heating plant must havea minimum height based on its installed thermal capacity:
- ≥ 2.0 m for systems with a capacity of less than 116 kW;
- ≥ 2.30 m for systems with a thermal output between 116 and 350 kW;
- ≥2.60 m for systems between 350 and 580 kW;
- ≥ 2.90 m for systems with a capacity greater than 580 kW.
The minimum heights for each category may be reduced by 30 cm (with the exception of the category for power ratings below 116 kW, which cannot be less than 2 m), provided that the ventilation area is increased by 100% and the same devices required for power plants located at altitudes below 5 m are installed .
Ventilation of the Heating Plant
Ventilation of the boiler room is another critical factor: in the event of a gas leak, the boiler room must prevent the formation of gas pockets near the ceiling. The room must therefore have permanent openings flush with the ceiling to prevent the accumulation of methane. The area of these openings is proportional to the heat output and depends on the type of room ( above ground, basement, or underground) and whether or not gas detection systems are present.
Access to the heating plant and door specifications
Access to the boiler room can be gained either from the outside or from the inside. In the latter case, however, access must be through a hallway with REI-compliant characteristics, equipped with ventilation openings and a minimum surface area as specified if the heat output exceeds 116 kW. Under no circumstances may the boiler room be accessed directly from a room without a hallway in between.
The door to the boiler room—which must open outward for systems with a capacity exceeding 116 kW—must always meet a minimum height of 2.0 m and a minimum width of 0.6 m, and must be constructed of Class 0 material according to fire resistance ratings.
Doors in thermal power plants are typically equipped with automatic self-closing devices to ensure that the door closes, thereby containing the spread of fire and ensuring the effectiveness of fire compartmentation.
Relevant Regulations and Further Information
The measures outlined above are the most important requirements for gas-fired heating systems that are integrated into the building’s structure—which is one of the most common scenarios.
For a more in-depth and comprehensive discussion, please refer to the Consolidated Text of Ministerial Decree dated November 8, 2019, which provides a detailed account of all the necessary precautions for each possible scenario.
For further information on this topic or for a consultation, please contact our Enertech Solution team.
