Boiler room gas detection

Most gas boiler rooms run without permanent monitoring and a gas leak could stay unnoticed. The gas detection controllers for the boiler room mainly remove these risks by triggering valve actuators. In the presence of ignitable gas detection (liquefied petroleum gas or natural gas), a controller will shut down the gas supply with a safety solenoid valve (tools available inside the taps with suitable fittings) placed upstream and, if possible, outside the technical room.

Boiler rooms standards and regulations

Gas detection systems in large boiler rooms are subject to specific regulations, but common sense dictates that the same recommendations apply to smaller systems, whatever the sector of activity. For lighter-than-air gases (such as methane - CH4 - for example), the device should be positioned above the burner; for heavier-than-air gases (such as butane or propane, for example), the multi-gas detector should be positioned below the burner.

For gas boiler rooms with high ceilings (over 3 meters), an additional gas detector is placed at the highest point of the boiler room (or ideally in the extraction intake flow when there is one), to obtain double detection (burner and ceiling), whatever the number of burners (hydrogen or other fuel boilers).

All the tools required to operate boiler room equipment are referenced according to the standards and regulations in force. The decree of June 23 1978 applies to boiler rooms with a capacity of over 70 kw or 85 kw up to 2000 kw, and less than 2MW. Sheet 2910 of the order of August 3, 2018, determines the new modalities by reducing the classification threshold to 1MW for Installations Classées Protection de l'Environnement. This change makes it mandatory to install fixed gas detection in boiler rooms.

Boiler room gas detection: different alarm thresholds

A gas detection controller (such as the MX32 V2 gas detection controller) for boiler heating systems manages every fixed gas detector and features relays for alarm signals and valves actuators:

  • Level 1: 10 or 15 % of the LEL (lower explosive limit), visual and audible signal with alarm report for rapid intervention on the site presenting a danger
  • Level 2: Between 20 and 40 % of the LEL, gas supply shutdown through a manual reset boiler gas valve (human intervention is required to restart the boiler)
  • Level 3: Only for biggest gas boiler heating systems. Starting at 60% of the LEL, direct action on the main LV board and complete shutdown of any power supply (except the boiler room gas detection controller)

Another type of boiler room

Industrial steam boiler room is very popular in the food, metal, chemical, and other industries. At a time when we're looking for a better way to reduce our energy bills, this type of heating meets today's challenges by being more ecological and environmentally friendly. To achieve results, it's essential to monitor the evolution of consumables such as water and gas. Maintenance and control of the equipment are also essential for the proper operation of the steam boiler. In homes equipped with a boiler, the risk of carbon monoxide emissions cannot be ruled out.

Gas detectors in boiler rooms

Connected to a central gas detection system, the gas detector inside a boiler room housing several boilers is an essential element in worker protection. The use of high-tech detection equipment, which requires daily bump test, is essential to the smooth operation of a boiler room. It provides an early warning of leaks in gas-fired boiler rooms, helping to protect employees from potential explosions or poisoning. Some are suitable for ATEX zones, such as the OLCT100 fixed gas detector for explosive, toxic, and refrigerant gases.

The number of devices to be installed depends on the number of boilers, and their location within the building is determined by the risk of leakage. One detector per boiler is preferred, with a central detector at the top due to the weight of natural gas, which is lighter than air, and a device above the heating equipment to trap the gas. The lower part of the system features a ventilation system with fresh air intake, while the upper part features an air exhaust system to ensure continuous air scavenging even when the burners are shut down.

Maintenance of all the tools used in a boiler room gas detector is essential. Personnel must be available regularly to carry out manual checks, calibrations, and preventive maintenance. An explosimeter sensor must be inspected and calibrated periodically. For portable gas detectors, a docking station is ideal for daily bump testing, to check that the sensor and cells are working properly.

Portable 4 gas detector – VENTIS-MX4

ATEX fixed gas detectgor – OLCT10

Spyglass SG50 series optical flame detectors

Spyglass IR3-H2 flame detector

Components for AIR/GAZ lines in boiler rooms

The main (and most effective) form of control in the event of an unexpected gas supply is to cut off the gas supply using a gas solenoid valve, preferably with automatic or manual reset. The product's power supply passes through the gas detection control unit (fail-safe relay), which closes in the event of an alarm as soon as a lack of voltage is detected. This gas cut-off ensures optimum safety.

Gas line accessories offer enhanced protection for solenoid valves. The two essential safety products are block valves, which stop the flow of gas at a defined point, and gas pressure switches, which measure the minimum presence of gas or excessive pressure. A solenoid valve is an aluminum or brass fitting that opens or closes a circuit by sending an electric current through a magnetic field. It generally has female-to-female connections to standardized flanges. This range of tools is varied and affordable.

The manometer is also a good complement. It quantifies the pressure of the liquid or gaseous fluid in a heating system. Regular reading of the level is necessary to detect any problems in the atmosphere. 

The dead-glass box is an excellent safety accessory, protecting the solenoid valve from corrosion.


Manual reset gas solenoid valve – ELK600

Automatic reset gas solenoid valve – ELK700

Air - gas low pressure switch - DWR

Safety box to protect valves - BSVD