Installation of gas pollution sensors: standards, height, installation

Installing gas detectors: standards, height, installation and verification

The safety of premises where gas equipment is used largely depends on timely leak detection. A gas detector responds to exceeding the threshold concentration of flammable or toxic gases and triggers an alarm, often also shutting off the fuel supply. However, even a certified device will be useless if it is placed in violation of regulations or connected incorrectly. In this article, we will analyze how to choose a location, at what height to mount the sensor depending on the type of gas, how many control points are needed for a boiler room or a private house, and what requirements apply to installation and periodic verification.

General information on the operating principles and types of gas analysers is provided in the article about gas detectors. It is also useful to familiarise yourself with the architecture of automation systems in the article gas monitoring system.

1. Regulatory framework and mandatory installation

The placement of detectors is regulated by several documents. Basic requirements for boiler rooms are set out in SP 60.13330.2016 “Heating, ventilation and air conditioning”. Clause 6.6.21 requires that rooms with gas heat generators be equipped with methane and carbon monoxide detectors, as well as an electromagnetic shut‑off valve. Additional instructions are contained in SP 41‑108‑2004 “Apartment heating of residential buildings with gas‑fired heat generators”. Installation standards in residential premises with gas stoves are advisory, but since 2020, the Ministry of Emergency Situations and gas supervision authorities insist on mandatory equipping. All work must be carried out in accordance with GOST R 52136‑2003 (gas analysers) and the technical regulation on building safety.

2. Choosing a location: dependence on gas type

The main factor determining the position of the sensor is the density of the gas relative to air. Methane CH4 (natural gas) is lighter than air, so when leaking it rises to the ceiling. Propane (liquefied gas) is heavier than air and spreads along the floor. Carbon monoxide CO is close to air in density, but due to convective flows from warm equipment it initially spreads in the upper zone and then distributes throughout the volume. Thus, the installation height is strictly linked to the gas type.

The recommended placement zones are given below:

• Methane CH4: mounting under the ceiling, at a distance of 10–30 cm from the ceiling. If the room has high ceilings (more than 3 m), the detector is installed at a height of at least 3 m so that it is in the gas accumulation zone.
• Propane, butane: installation near the floor, no higher than 30 cm from the finished floor level. In a kitchen with a gas stove running from a cylinder, the gas detector is placed exactly at the bottom.
• Carbon monoxide CO: mounting at a height of 1.5–1.8 m from the floor, which corresponds to the human breathing zone. In a boiler room, an additional sensor is also installed at a height of 0.5–0.8 m, since CO can accumulate in the lower part of the room in the absence of circulation.
• Combined CH4+CO detectors: if one housing with two sensors is used, it is mounted at a height of 1.8–2.0 m as a compromise. However, two separate devices, each at its own height, are preferable.

3. Placement standards within a room

In addition to height, there are rules regarding location relative to building structures and equipment:

• Distance from the gas appliance (stove, boiler, water heater) — no more than 2.0 m horizontally. If the room allows, 1.0–1.5 m is optimal.
• Installation closer than 1.0 m to windows, doors and ventilation grilles is prohibited, as drafts distort the actual concentration.
• Do not mount the detector in close proximity to exhaust hoods, in corners with poor circulation, or behind cabinets.
• In a boiler room with a methane sensor placed on the ceiling, areas where a stream of hot air from the boiler may hit should be avoided.

For a gas detector in a boiler room, the installation standards require placing the methane sensor above the boiler, and the CO sensor in the area where personnel may be present, at a distance of 1.5–2.0 m from the source. If the boiler room area exceeds 15 m², two detectors of each type are installed to cover the entire zone.

4. Number of control points

How many detectors are needed for a particular facility depends on the layout and equipment composition. Approximate figures:

• Apartment with a gas stove: one methane detector in the kitchen. If a flow‑through water heater is installed, an additional CO detector in the same room or in the corridor.
• Private house with a gas boiler in a separate boiler room: in the boiler room — at least two detectors (methane under the ceiling and CO at breathing level). In the kitchen, if there is a stove, another methane detector.
• Boiler room with a capacity over 60 kW: two detectors of each gas, evenly distributed throughout the room.
• Garage, basement with gas equipment: CO and methane detectors; when using propane, a propane detector near the floor.

All detectors must be integrated into a common circuit with a valve and a control panel. The architecture of such systems is described in detail in the article gas monitoring system.

5. Installation and connection

Installation of gas detectors is carried out after finishing work is completed. The housing is fixed with dowels or self‑tapping screws to a load‑bearing wall using the standard mounting holes. Power is supplied from the 220 V mains via a separate 6 A circuit breaker — this is a safety requirement to keep the device energised even when other protections are triggered.

How to connect a gas detector to an electromagnetic valve? A signal cable with a cross‑section of at least 0.5 mm² connects the relay output of the detector to the valve coil. The valve is normally closed, meaning that without voltage it shuts off the gas. During installation, the polarity specified in the data sheet must be observed. For combined models that control two valves, two pairs of contacts are used. The connection diagram must be checked before applying power.

When using several detectors and a control panel, all devices are linked in a loop. The gas alarm panel coordinates the operation of the sensors and the valve, providing audible and visual indication. One of the models that allows such connection is the DZI GERDA gas detector, which supports the RS‑485 interface.

Earthing of the housing is not required for plastic models, but if the detector is metal or shielded, the earth wire is connected to a special bolt. All connections are insulated.

6. Calibration and verification

Calibration is performed at the factory, but periodic verification is required during operation. For domestic detectors, the verification interval is 12 months; for industrial ones — 6 to 12 months depending on conditions. Verification in a boiler room involves supplying a reference gas mixture to the sensor and monitoring its response. If the device does not fall within the permissible error (usually ±10% of the threshold), it is repaired or replaced.

For a self‑check of functionality once a month, press the test button that simulates a gas leak. Some models require calibration with clean air — this procedure is performed on site according to the instructions.

7. Operating rules after installation

After successfully installing the detector in a house or boiler room, it is important to follow the operating regime. At least once every six months, clean the ventilation openings of the housing from dust, and do not paint or cover the detector. When an alarm is triggered, immediately ventilate the room, turn off electrical appliances, and do not use open flames. After the leak is eliminated, the valve is reset manually.

8. Typical installation mistakes

Common errors include: installing a methane detector near the floor, placing it next to ventilation, missing a separate power circuit breaker, connecting the valve without checking polarity. All of these lead to false alarms or failure to trigger in an emergency. Therefore, installation should be entrusted to a specialised organisation, and the certificate of completed work should be kept together with the device passport.

9. Conclusion

Correct installation of gas detectors is the key to protection against explosions and poisoning. Strict adherence to the height depending on the gas type, placement rules and connection diagram ensures that the alarm will detect a dangerous concentration in time and shut off the fuel supply. Regular verification maintains metrological characteristics at the proper level. Questions of choosing a specific model are covered in the overview article linked above.