How to choose a gas leak detector for home and business
Why to solve gas leak detection professionally, not just "by eye"
A gas leak is one of the risks that in the normal operation of a household or boiler room only becomes apparent when it is already too late - that is, during an explosion, fire, or carbon monoxide poisoning due to incomplete combustion. Human sense of smell can detect the characteristic odor of odorants (usually tetrahydrothiophene or mercaptans added to natural gas and propane-butane), but relying on it in an environment with technology, in a basement, boiler room, or in a larger leak-prone gas line is risky. A gas leak detector is therefore a device that should be in every household with a gas appliance as self-evident as a fire extinguisher or smoke detector - and in industrial or commercial operations with gas boilers, dryers, burners, or technological gas lines, it is required in most cases directly by the project documentation or by the inspection technician.
This article was created as a practical guide to selection - it is based on real situations that repeat during the sale and installation of gas detectors: from a simple home kitchen with a gas stove, through a family house with a gas boiler in the basement, to a commercial kitchen or boiler room with multiple appliances. In the category detectors, you will find the specific models we refer to in the text, including variants with a built-in solenoid valve.
Principle of gas detector operation
A gas detector is an electronic device with a sensor that reacts to the presence of flammable gas in the air. In commercially available detectors for households and smaller operations, the most commonly used is a semiconductor (catalytic or metal-oxide) sensor, which changes its electrical conductivity depending on the concentration of gas in the surrounding air. When the concentration exceeds a set threshold value (usually expressed as a percentage of the lower explosive limit - LEL, from the English Lower Explosive Limit), the detector activates an acoustic and visual signal and, in the case of models with a solenoid valve, also sends a command to close the gas supply.
It is important to understand that the detector does not react to the smell (odorant), but directly to gas molecules - it is therefore effective even in situations where a person would not notice the smell, or could be used to it (so-called olfactory adaptation), or has a weakened sense of smell, which is common, for example, in older people.
Natural gas vs. propane-butane: why it affects the choice and placement
The first question to ask when choosing a detector is the type of gas that is present in the space. Natural gas (methane, CH4) is lighter than air - its density is approximately 0.55 to 0.65 in relation to air, so it accumulates at the ceiling during a leak. In contrast, propane and butane (LPG) are heavier than air (density approximately 1.5 to 2 in relation to air) and fall to the floor during a leak, accumulating in pits, channels, and the lowest parts of the room.
This physical property directly determines where the detector should be mounted - for natural gas in the upper third of the room (typically 15-30 cm below the ceiling), for propane-butane, on the other hand, low above the floor (typically 15-30 cm above the floor, near possible leak sources). A detailed analysis with precise recommended heights and distances from appliances can be found in the separate article "Placement and mounting height of gas detectors according to gas type," here we just summarize the principle and add practically verified values.
In practice, we encounter a mistake when a customer buys a detector and installs it "by habit" - for example, low above the floor in an apartment with natural gas, because they had a CO detector there before. The result is a detector that will not actually detect a leak at the ceiling from a leaky connection of a stove or boiler, because the gas simply does not reach the sensor quickly enough. Therefore, the type of gas is the first thing to be resolved when choosing and installing - and if you have both types in one operation (e.g., natural gas for heating and propane-butane in a cylinder on the terrace or in the garage), you need two separate detectors in two different places, not one universal one.
Stand-alone detector vs. detector with solenoid valve
The second key decision is whether a detector that only signals a leak (visually and acoustically, optionally with a dry contact for connection to a control panel or GSM alarm) is sufficient, or whether it is necessary for the detector to also physically close the gas supply via a solenoid (electromagnetic) valve.
A stand-alone detector is suitable where there is a permanent presence of staff who can react immediately to the signal - for example, in a home where a person is present most of the time, or in an operation with continuous staffing. A detector with a solenoid valve is, on the other hand, essential wherever there is a risk that no one will be present in the space at the time of the leak - typically a cottage, recreational property, boiler room without permanent staff, warehouse, garage with an LPG cylinder, or a commercial operation outside of opening hours. In such a case, the detector automatically closes the gas supply when the threshold concentration is exceeded and prevents further leakage regardless of whether anyone is nearby.
A practical example from a typical order: a family house with a gas boiler in the basement, the owners living upstairs. We selected the Gas Detector AVANSA 100M as a standalone unit with an 85 dB acoustic signal, because someone is almost constantly present in the house and the signal from the basement can be heard upstairs through the stairs. On the other hand, for a weekend cabin we recommended the variant Gas Detector AVANSA 100M + solenoid valve G1/2" DN15, because no one is present in the building during the week to react to the alarm, and the leak could otherwise continue for several days.
A more detailed comparison of the advantages and disadvantages of both approaches, including recommendations according to the type of operation, is discussed in a separate article: Gas detector with solenoid valve vs standalone detector: what to choose.
What parameters to consider when choosing a specific model
When selecting a specific type of detector, I recommend monitoring several technical parameters that determine whether the device will actually function reliably in the given environment and without unnecessary false alarms.
Type of sensor and detected gas
The majority of commonly available detectors for households and smaller operations are designed universally for flammable gases (natural gas - methane, propane, butane, or LPG mixtures). When choosing a model, it is important to verify that it covers exactly the gas used in the building - the relevant differences in sensitivity and threshold settings are described in the article Gas detector for natural gas vs propane-butane: what difference and what it means for selection.
Power supply
Detectors are supplied either with a 230 V mains power supply (the most common solution for permanent installation at home and in operations), or with battery/accumulator backup in case of a power outage. For models with a solenoid valve, backup power is especially important - if a power outage occurs simultaneously with a gas leak (which can realistically happen, for example, during a storm), the device must be able to close the valve even without mains voltage, or the valve remains in a safe (closed) position in case of power loss - this behavior must always be verified in the technical specifications of the specific model before installation.
Sensitivity and threshold setting (% LEL)
A quality detector allows reacting to a concentration significantly lower than the lower flammability limit of the gas - typically, the alarm is triggered already at 10-20 % LEL, which provides sufficient time to respond or automatically close the supply before the concentration approaches a dangerous level.
Signaling and outputs
The basic signaling is acoustic (siren, usually 80-90 dB at a distance of 1 m) and visual (LED, blinking). For connection to other technologies (FES, FAS, boiler room control system, GSM communicator), it is important whether the detector has a dry contact relay output - this is especially appreciated in commercial operations, where the signal from the detector needs to be sent to a central dispatch or sent as an SMS/notice to the responsible person.
Operating temperature and humidity range
In boiler rooms, garages or technical rooms without heating, the temperature can drop below freezing in winter and rise well above 30 °C in summer. Always verify that the selected model is suitable for the given climatic conditions - cheap sensors outside the specified temperature range lose accuracy or report false alarms.
Comparison of models AVANSA 100M and AVANSA 150MC
In this category you will find two main series - AVANSA 100M (available also in a version with a built-in solenoid valve in three thread sizes) and AVANSA 150MC. A detailed comparison including the third series AVANSA 200M can be found in a separate article AVANSA 100M vs AVANSA 150MC vs AVANSA 200M: comparison and recommended use, here we present a brief practical overview for quick decision making.
| Parameter | AVANSA 100M | AVANSA 150MC |
|---|---|---|
| Intended use | household, smaller operation | household, operation with higher requirements |
| Mounting | on the wall, standalone unit | on the wall, compact design |
| Solenoid valve | optional in the package (G1/2", G3/4", G1") | separately / according to configuration |
| Suitable for | apartments, family homes, garages, cottages | households and smaller commercial spaces |
Practical recommendation: for a standard family home with one gas appliance (boiler or stove), the standard choice is Gas detector AVANSA 100M, or even in combination with a solenoid valve, if there is no permanent supervision in the house. For more demanding operations or as an alternative solution with different signaling parameters, it is worth considering Detector AVANSA 150MC - the specific choice is always recommended to be consulted according to the number and type of appliances in the building.
Selection of solenoid valve according to pipe dimension
If you decide on a solution with automatic closure of the supply, you need to choose a solenoid valve with the correct light (DN) corresponding to the dimension of the existing gas pipe. In the range there are three most common sizes:
- G1/2" (DN15) - the smallest common dimension, typical for a connection to a single appliance (stove, smaller boiler) - Gas detector AVANSA 100M + solenoid valve G1/2" DN15
- G3/4" (DN20) - medium dimension, suitable for the main distribution in a family home with multiple appliances - Gas detector AVANSA 100M + solenoid valve G3/4", DN 20
- G1" (DN25) - larger dimension for higher flow, typical for boiler rooms, operations or buildings with higher gas consumption - Gas detector AVANSA 100M + solenoid valve G1" DN25
Choosing an incorrect dimension of the valve (for example, too small compared to the existing pipe) can cause an unacceptable pressure drop and insufficient gas flow to the appliances, on the other hand, a valve that is too large for a small connection is unnecessarily oversized and expensive without real utility. The exact procedure for correctly determining the required dimension according to the diameter of the existing pipe and the installed power of the appliances can be found in the article How to choose the right solenoid valve for the detector (G1/2", G3/4", G1").
Where exactly to place the detector - summary of principles
In addition to the selection of the type of gas itself, it is important to comply with the distance from interference sources and from the appliance itself. In general, the following applies:
- do not place the detector directly above the stove or close to the burner - heat and water vapor distort the measurement and shorten the sensor life,
- maintain a minimum distance from the corner of the room (in corners, air flow is limited, gas may not reach the sensor quickly enough),
- avoid placing in a draft near doors or windows, where gas concentration is diluted before it reaches the sensor,
- in a boiler room with multiple appliances, consider multiple detectors instead of one universal one in the center of the room.
Step-by-step installation procedure
The installation of a gas detector, as well as a detector with a solenoid valve, essentially consists of several steps that should be followed in the correct order - the detailed electrical procedure including wiring diagrams can be found in the article "Installation and wiring of a gas detector with a solenoid valve". Here we provide a simplified overview.
This practically means: (1) determine in advance whether it is natural gas or propane-butane, and choose the installation height accordingly; (2) before any intervention in the pipe, close the main gas shut-off valve and turn off the electrical supply in that circuit; (3) mechanically mount the detector body on the wall and the solenoid valve on the pipe in the direction of flow according to the arrow on the valve body; (4) connect the detector to the valve and possibly to further signaling according to the manufacturer's diagram; (5) after completing the installation, perform a leak test of the connections (e.g., using a foaming leak detection spray, never an open flame); (6) finally, perform a function test - either with a calibration gas or at least by pressing the test button, which confirms that the acoustic signaling and valve closure actually work.
The installation of a solenoid valve into an existing gas line should be carried out or at least approved by a qualified gas technician / inspection technician in any case - it is an intervention in the gas equipment, which is subject to the relevant technical standards and in many cases also a mandatory inspection after the intervention.
False alarms and common mistakes in selection and operation
In practice, we most often encounter these situations that lead either to false alarms or, on the contrary, to the detector not reacting in a critical moment:
- incorrect installation height - a detector for natural gas mounted too low, or a detector for propane-butane mounted near the ceiling,
- placement near steam and chemicals - cleaning agents, paints, thinners or even ordinary steam from cooking can temporarily "blind" the sensor or trigger a false alarm,
- missing or neglected calibration - sensors have a limited lifespan (typically several years) and over time they lose sensitivity, which can lead to a delayed or no reaction in the case of a real leak,
- underestimating power backup - a detector without backup power will stop working during a power outage, precisely when the risk of damage to the supply is highest,
- incorrect dimension of the solenoid valve - an undersized valve restricts gas flow to the appliances, an oversized one is unnecessarily expensive.
A detailed analysis of specific types of faults and recommendations on how to avoid them can be found in the article "Common faults and false alarms of gas detectors", the topic of calibration and sensor lifespan is covered in a separate text "Maintenance, calibration and lifespan of gas detector sensors".
Selection according to type of building - practical scenarios
Summary of recommendations according to the most common types of buildings we encounter in practice:
- Apartment with a gas stove - a standalone detector placed above the stove in the upper part of the kitchen (natural gas) is sufficient, without the need for a solenoid valve, provided that someone is practically always present in the apartment.
- Detached house with a gas boiler in the boiler room/basement - we recommend a combination of a detector with a solenoid valve directly on the main supply to the boiler room, especially if the basement is rarely occupied.
- Cottage or recreational building with an LPG cylinder - a detector with a solenoid valve is definitely recommended, placed low above the floor near the cylinder and the appliance, because the building is often unattended for long periods.
- Garage with an LPG cylinder or vehicle running on LPG - a detector near the floor, ideally with a solenoid valve and connection to signaling outside the garage (e.g., in the living part of the house).
- Commercial kitchen or catering establishment - due to the higher number of appliances and shift operation, we recommend multiple detectors placed according to individual sections, with output to a central dispatch or at least with an audible alarm audible throughout the entire establishment.
- Boiler room with multiple boilers or technological piping - a combination of multiple detectors with common or separate solenoid valves according to how individual piping branches can be separated, with emphasis on a larger valve size (G3/4" or G1") matching the higher gas flow.
Common questions about selecting a gas leak detector
Am I required by law to have a gas detector?
In several types of premises (commercial kitchens, boilers above a certain power, technological areas) a gas detector is required by the project documentation, technical standard or by the insurance conditions. In a regular household it is not legally required in most cases, but due to the risk it is clearly recommended especially where the gas appliance is located in a closed space without permanent supervision.
Is one universal detector enough for the whole house?
In most households with one gas appliance in one room, one detector placed correctly according to the type of gas is sufficient. In the case of multiple rooms with appliances (e.g., a kitchen with a stove and a separate boiler room), we recommend a separate detector in each room, because one detector cannot reliably cover distant or separate areas.
How often should the detector be tested and the sensor replaced?
We recommend performing a functional test using the test button approximately once a month, and calibration or inspection by a qualified service technician according to the manufacturer's instructions (usually once a year to once every two years). The sensor has a limited lifespan, and after its expiry (usually several years), the entire sensor module or detector must be replaced, even if it appears to be functioning properly from the outside - for more details, see the article on sensor maintenance and lifespan.
Can I install the solenoid valve myself?
Mechanical mounting and electrical connection can be handled by a skilled technician, but any work on the gas supply line (disconnecting the pipe, installing the valve into the line) should be carried out or at least checked by a qualified gas technician, as it involves a restricted technical installation where connection tightness must be ensured and in many cases followed by an inspection.
What happens during a power outage?
It depends on the specific model - some detectors have battery backup ensuring the signaling function remains operational during a power outage, while in some versions the solenoid valve switches to a safe (closed) position when power is lost. Always verify this behavior in the technical documentation of the selected model before purchase, especially if the building is unattended.
What is the difference between AVANSA 100M and AVANSA 150MC in standard selection?
Both models are intended for households and small businesses, and differ in design, the possibility of combining with a solenoid valve in the package, and some technical signaling parameters. For a standard family home with one appliance, the most common choice is AVANSA 100M, or directly in the version with a built-in valve according to the pipe dimensions. A detailed comparison can be found in a separate article dedicated specifically to this topic.
Summary at the end
Selecting a gas leak detector is not just about buying "any" device from the shelf - several factors actually matter and influence each other: the type of gas in the building (and the derived placement), the presence or absence of permanent supervision (and the derived need for a solenoid valve), the dimensions of the existing piping (if you decide on automatic closing), and finally the specific technical parameters of the model - power supply, sensitivity, outputs, and operating conditions. In the category detectors, you will find a complete range including all mentioned AVANSA variants with solenoid valves of various dimensions - when selecting, we recommend following the steps described in this article precisely, and in case of any uncertainties, consult a technician before the actual purchase, so you do not have to deal with replacing the valve or detector after an unsuccessful installation.
Do you have a question on this topic?
Having trouble deciding or dealing with a specific situation in your home? Write to us - we are happy to help.