Gas Leak Detector: Selection, Installation, Wiring Diagram and Testing
Gas leak detector is a device designed for continuous monitoring of the concentration of flammable or toxic gases in the air. When a preset threshold is exceeded, it emits an audible and visual alarm, and can also shut off the gas valve. Such systems are vital in homes, apartments, boiler rooms and industrial facilities to prevent explosions and poisoning.
In this guide, we will look at how to choose, where to install and how to connect a gas alarm, as well as discuss the specifics of operation in a private house and apartment, for a gas boiler and boiler room.
1. Purpose and operating principle
Gas monitoring system is designed for early detection of natural gas (methane), liquefied gas (propane-butane) or carbon monoxide (CO) leaks. It consists of one or more sensors connected to a controller and can control shut-off valves — an electromagnetic valve. When the alarm is triggered, the valve shuts off the gas supply, and the ventilation (if available) is turned on forcibly.
Such devices come in two main types based on the sensing element:
- Optical (infrared) — uses the principle of gas absorption of infrared radiation. Accurately determines the concentration of methane and propane. Does not require frequent calibration, is not poisoned.
- Semiconductor — cheaper but less stable, requires periodic verification.
- Electrochemical — best for detecting carbon monoxide (CO).
The market offers universal models, for example, Gerda Gas Leak Detector, as well as specialized ones — infrared DZI-3 detector.
2. Types of detectors by target gas
- For methane (CH₄) — for natural gas, which is lighter than air. Methane detectors are installed under the ceiling.
- For carbon monoxide (CO) — a product of incomplete combustion. Very dangerous, odorless. CO detectors are mounted at a height of 1.5–1.8 m from the floor (at breathing level).
- For liquefied gas (propane-butane) — heavier than air, detectors are placed at the bottom, 30–50 cm from the floor.
- Combined — respond to several gases (e.g., methane + carbon monoxide).
3. Installation of gas leak detector: where and how to place
Proper installation of the detector is critical for its effective operation. Main rules:
- Avoid places with strong air currents (ventilation grilles, drafts) that distort readings.
- Do not install in corners, niches, behind cabinets — air stagnates there.
- Distance from gas equipment — no more than 4 meters horizontally.
- For methane (natural gas) — installation height 0.3–0.5 m from the ceiling, but not lower than 0.3 m from the top point of the room.
- For propane (liquefied) — at a height of 0.3–0.5 m from the floor.
- For carbon monoxide — at a height of 1.5–1.8 m from the floor (at head level).
3.1. Installation in an apartment
In an apartment, gas detectors are usually placed in the kitchen near the gas stove or gas boiler. If liquefied gas in cylinders is used, the detector is placed at the bottom; if mains methane — under the ceiling. They are often required when gas is commissioned. Many modern apartments are also equipped with a carbon monoxide alarm from the gas boiler.
3.2. Installation in a private house and for a boiler room
For a private house, a gas detector is mandatory in the room with the gas boiler (boiler room). The same rules apply: for methane — under the ceiling, for propane — near the floor. In a boiler room in a private house, the detector must be connected to an electromagnetic valve that shuts off the gas at the inlet. It is also recommended to install a gas monitoring system with signal output to a control panel or GSM module.
Comprehensive solutions for boiler rooms and industrial facilities are presented in the gas level monitoring system section.
4. Wiring diagram for gas leak detector
The wiring diagram depends on the device type and its functionality. Typically, the detector has terminals for:
- Power supply (220 V or 12/24 V).
- Output relay (dry contact) for connecting an electromagnetic valve.
- 4–20 mA output or RS-485 for data transmission to a controller.
- Connecting an external siren or light annunciator.
When connecting the detector with a valve, the electromagnetic valve is normally open; when the alarm triggers, the relay opens the circuit and the valve closes. To restore gas supply, a manual reset is required (after eliminating the cause).
For a typical household system, a two-wire or three-wire scheme is used. It is recommended to entrust installation to a qualified specialist.
5. Detector with electromagnetic valve: advantages
Using a detector with an electromagnetic valve allows you to automatically shut off the gas supply in case of a leak. This is critical for boiler rooms, where a leak can lead to an explosion. The valve is installed on the gas pipeline in front of the meter or boiler. When the alarm is triggered, it shuts off the gas, preventing the accumulation of an explosive mixture. Such systems are mandatory for new homes with gas heating.
6. Testing and verification of gas detectors
Testing of the detector should be carried out regularly — at least once a month. The simplest method: bring a lit lighter to the detector (without igniting the gas!) — the device should react to the vapors of unburned fuel. However, this does not replace professional verification.
Verification (calibration) of gas detectors is performed by specialized organizations using gas mixtures of known concentration. The frequency of verification is usually once a year for household appliances and every 6 months for industrial ones. A verification certificate is issued based on the results. Without verification, readings may be inaccurate, which is dangerous.
7. Additional functions and requirements
- Gas monitoring can be part of a “smart home” system.
- A stationary detector (not portable) is mounted on a wall or ceiling and powered from the mains.
- For rooms with high ceilings (more than 4 m), detectors must be installed at different levels.
- For a gas boiler, a carbon monoxide detector is mandatory, as the boiler may malfunction and emit CO.
8. Conclusion
Installing a gas leak detector is a mandatory safety requirement when using gas equipment in an apartment, private house or boiler room. The correctly selected type (for methane, carbon monoxide, propane), proper installation at the right height and connection according to the diagram with an electromagnetic valve significantly reduce the risks of explosion and poisoning. Regular testing and annual verification ensure the reliability of readings.
To equip your facility, we recommend high-quality devices: universal DZU Gerda detector (for methane/propane/CO) or infrared DZI-3 detector for critical facilities. Comprehensive systems are presented in the gas level monitoring system section.
