Fire alarm: 7 keys to buying the best detector for home

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Fire detector and alarms

I still do not understand why in France it is mandatory to have a fire alarm at home (if you do not have it, the home insurance is not valid) and in Spain, this is not mandatory security measures. It's about saving lives, and a automatic fire detector for home, overwhelmingly, it is cheap.

Notice! On average, almost seven out of ten deaths are caused by smoke inhalation and at night, you don't even know about it. And one of the things that these devices do well in the event of an accident inside the home, is detect smoke or heat in its initial phase.

The early detection of a home fire, it is a very serious matter. You have to see many aspects and buy the right device! In the following guide we explain it in detail …

1.- What systems are there to detect a fire

Within emergency systems, there are two methods to detect a fire (Initial phase of the presence of smoke or heat - flame): an automatic fire system and a second, which is a manual activation:

  • Automatic fire detection device. Device that uses an «X» technology (We will see later) at certain points in a space. It can be one element or several and they serve to detect fires early by emitting some type of alarm signal or audible (Even warnings to firefighters, for example).
  • Manual fire detection device (Human detection). In this case, we are the ones who activate the alert - normally by means of a button - to give the warning to the emergency services, which in turn will activate an audible or visual signal.

The installation of fire alarms can range from a smoke sensor for homes, the basic appliance to avoid material and personal injury, up to a complex alert system that even activate barriers to protect us (closing doors, automatic extinguishing actuation, sprinklers, alerts to firefighters, etc):

Here we could also put home security cameras, since some also capture heat.

Voucher! We already understand how complex these emergency systems can be, but, what kind of fire alarm can I install at home

If we do not know what types of fire alarm they sell, we will not be able to choose the best device according to our needs.

2.- Types of fire alarms they sell

The question is… What are the most common heat detectors? Although manufacturers are always bringing new technologies, we generally find the following types of fire alarm in the shops:

  • Thermostatic heat detectors. Is he thermal detector. It turns on with an acoustic signal when the ambient temperature of a space exceeds a certain value - usually 58º - for a certain time.
  • Thermovelocimetric heat detectors. It is a thermal detector that turns on when the rate of increase in temperature exceeds a certain value, about 8 ° C per minute, for a specified time.
  • Combination heat detectors. They incorporate a thermostatic element (controls the temperature) and another velocimetric (speed of heat increase).
  • Ionic smoke detector (Invisible smoke and of course visible smoke too). Any fire produces gases (even if it does not initially have smoke or flame) this device detects them. They are activated due to the influence produced by combustion products on the electrical current generated in an ionization chamber.
  • Optical smoke detectors (Visible combustion smoke). They also call them photoelectric detectors or, for large spaces, linear optical light beam detectors. In short, an optical detector has a lens that detects visible smoke that is activated by the influence of a darkening of the air or the diffusion of light (called Tyndall effect) in the infrared, visible and / or ultraviolet areas of the electromagnetic spectrum.
  • Gas detectors. They are sensitive to the gaseous products of burning and / or thermal decomposition (More industrial use).
  • Flame detectors. They are sensitive to the radiation emitted by the flames of the fire.
  • Multi sensor detectors. They are sensitive to more than one fire phenomenon, for example, such as smoke and heat.

You have to think that fire detectors that alert are designed - normally - to discover one or more of the three characteristics of fire: smoke, heat and radiation (A flame).

Watch out! We are not talking about gas detectors for when there are anomalies in; methane, propane, butane or those that detect the abnormal presence of carbon monoxide (CO) in the air they are different devices! Although we have manufacturers that offer us in the same element, a CO Detector + Smoke Capture.

A carbon monoxide (CO) detector does not sense smoke, just like a smoke sensor does not sense CO concentration levels.

To be clearer what models of fire detectors exist. Better we see the following scheme where more or less, we already observe what device you will need for home, an office, a local or whatever space:

If we see the following image, already real appliances. The models are very similar, but in reality they have different characteristics if we compare them between them; sensitivity, reliability, maintenance, price, etc.

Now comes the trick! EL comparing the different models to make sure we got the right choice …

3.- How to choose the best fire detector

First, I would like to make it clear that, in Spain, the current regulations do not require a fire or smoke detector to be installed in homes (later we will see when it is mandatory in residential, which depends on the evacuation height).

At this key point, we already know that the quality of the gadget is in the details and that is why we have written a fairly comprehensive guide. On these alert sensors we must look at:

Although the table above represents several points. The tolerable delay in detection is very important, that is, how quickly the device activates. Two important elements that make the mechanism of a fire detector be more reliable and efficient:

  • Sensitivity of the detector apparatus
  • Detector location

Ultimately, they determine the "delay" … When is a fire sensor activated?

What is really important in a system to detect a fire is the type of delay (Time to activate) in detecting smoke or fire, as appropriate.

One of the The main questions when we buy a smoke or fire detector is knowing when the alarm is activated in the event of a fire. This very important factor is given by the "sensitivity of the appliance" to a fire that comes together with its location and, of course, the type of appliance we buy.

4.- Comparison between devices and prices

In these security systems, each device is designed and manufactured for one use. If we have a device with a very high sensitivity, on certain occasions, it can give us false positives, for example, before smokers or in a kitchen due to water vapor or a little smoke.

To have it clearer, we first have a comparison of sensitivity in the mechanism to see how they act in the face of fire with: solid, liquid and electrical materials …

Sensitivity compared between detectors
Fire type
Detector type Solid materials Flammable liquids Electrical
Gas (ionic) high high Half
Optical smoke (photoelectric) high Short Half
Fixed temperature Short high Short
Speedometer Half high Short
Of flames:
Ultraviolet Short high high
Infrared Short high Short

Second, we compare fireproof equipment in relation to its characteristics of; sensitivity, reliability, maintenance and stability.

Detector type according to characteristics Sensitivity Reliability Maintenance Stability
Gas (ionic) high Half Medium Half
Optical smoke (photoelectric) Half Half Medium Half
Fixed temperature Short high Under high
Thermovelocimetric Half Half Under high
Of flames:
Ultraviolet high Half Medium Half
Infrared Half Half Medium Short

If we analyze the data a bit, in a home it is best to use a photoelectric smoke detector with alarm (optical device) or ionic. remember! They also sell self-contained smoke detectors that combine photoelectric and ionization technology. For home we would have:

  • For dining room, living rooms, bedrooms, corridors, stairs, basements: Photoelectric or ionic smoke detector (Or both in the same device).
  • For kitchen: It is not advisable to install a photoelectric device in the kitchen, the steam or smoke when something is roasted and the hood is not set, it can trigger a false fire alarm, but, in reality, many people use them and they are happy! Better a thermostatic detector or a thermovelocimetric detector (They act on heat). They are not usually installed in the bathroom.
Living rooms Dining room Bedrooms Corridors - Lobbies Basements Building plants Kitchen Garage
It is best to install a point smoke detector in areas of YES YES YES YES YES YES NO NO
It is best to install a heat detector in areas of NO NO NO NO NO NO YES YES

A device to locate photoelectric smoke is the most sensible thing for home. They're relatively cheap, high-quality, and work great

But… What else should you look at in these teams?

  • It is essential that the device is approved. It must bear the CE logo and the standard it complies with.
  • Check the warranty offered by the manufacturer.
  • Specific smoke alarms are designed to be installed in private homes (flat or house) and not in common areas of buildings.
  • Don't buy a cheap appliance not worth it! It will last longer and we will not have any problems. Look for quality and recognized brands that we are protecting our house and us.
  • Better to buy a wireless detector that works with battery or batteries (Check how long it lasts). We save the electrical installation at home by a professional. Another issue will be whether it is already for offices or buildings.
  • These mechanisms have evolved a lot technologically. Smart detectors; LED indicators for alarm (light signal), low battery and sensor failure, with screens and even that connect to the mobile with Wi-Fi connection to notify us. You decide here! But remember its function, diagnose a fire quickly.
  • By regulation, 10 Years must be changed.

The regulations consider that, after 10 years of use, they must be changed.

  • We always have to place them on the ceiling (We will explain No. and location later) but more or less keep it in mind due to the size of the device or the decoration.
  • A device for locating photoelectric smoke is the most reasoned for home. They're relatively cheap, high-quality, and work great - they do the job!
  • Even if they want to sell us combined devices; Carbon monoxide detector CO + Photoelectric smoke collector with ionic collector. We recommend that you buy them separately. You will have a better device and it will do its job well.
  • The acoustic - audible alarm signal must have a sound of at least 85 dB (See noise calculation article).
  • If we have home insurance. Verify that they comment when installing a fire system. You can have a discount on installation or on a device, a discount on insurance, etc.

But… How much does a home smoke detector cost? A sensor to alert us to a fire or smoke in a home costs between 20 to 50 Euros, a quality device. With Wi-Fi and other technologies, they exceed 80 Euros with more complex mechanisms such as Google Nest, for example.

Those that are wireless and punctual, more intended for the home, are cheaper. Those that are connected to the electrical network or linear in optics are already used more by professionals and increase in price.

Before buying, always compare prices. Look at the prices in large stores like English court, Ikea, Leroy Melin, Media Markt. We can also quickly compare prices that appear on Amazon or search for brands to verify the sale price.

Try to buy brands from manufacturers recognized in the market by professionals, for example; Notifier, Apollo, Bosch, System Sensor, Siemens-Cerberus, J.M. Systems, ESSER, Fire-lite there's a lot!

Now you are wondering … How many sensors do I need at home? Where do I have to put them?

5.- How many do I have to buy according to the surface

Obviously, it is not the same to know the number and locations to put them in an apartment, home or house (The regulations do not oblige us), than, in a building, warehouse, large premises, etc. (See next section on the obligations according to applications). But professionals should consider:

We simplify!….How many smoke detectors do I need for a flat, home or house? Although the rule does not require us to put one is house, we do refer to it to understand what number we need:

Maximum area monitored Maximum installation height to ceiling
Heat alarm sensor 20 m2 9 meters
Smoke alarm sensor 60 m2 12 meters

As in a normal home, the height to the ceiling does not usually exceed 3 meters, we already know that the alarm covers us 60 square meters (Covers 8 to 9 linear meters).

Be careful with the corners and under cover, you have to respect the measurements.

6.- Where is better to put a smoke detector

In this aspect you have to be consistent. If we only want one, better in the hallway without closing the door (at least the one leading to the dining room) and without obstacles. If we have several plants, we will need more….

They should preferably be placed in corridors and passageways of the home, and always on the roof!

For a suitable fire prevention we should consider:

  • This alarm system is preferably placed in corridors and passageways of the house.
  • In long corridors with a distance greater than 12 linear meters, the most correct is to install two, one at each end.
  • Between one and the other there can be a separation distance of 9 meters (No obstacles between the area to be protected and the detector).
  • The Ceiling height influences detection: the higher the smoke, the longer it takes to reach the appliance. If it is greater than 3 meters, you can shorten the distance.
  • Beware of false ceilings. Normally, nothing happens in homes, but in basements, offices or garages, the false ceilings allow smoke to pass through. The fire alarm It should be glued to the slab - upper ceiling, not to the false ceiling.
  • In bedrooms, that the doors are within a radius of about 3 m.

You shouldn't put smoke sensors in:

  • Do not put obstacles in the way or near air conditioning devices. Next to or above radiators or air conditioning vents (See article Air conditioning effects on health), windows, ventilation holes in the wall, etc.
  • You should not put them in areas with a lot of dust or dirt, as the dust that accumulates in the camera can negatively affect the performance (for example, garages).
  • You should not put them in areas where the normal temperature can exceed 100 ° F (38.7 ° C) or be below 40 ° F (4.4 ° C). If we have a device with high sensitivity, the positives will jump.
  • Near fluorescent lamps (Put a minimum distance of 1.5 m)

From a professional perspective, for more information. A manual that covers many characteristics and different useful tables is Asepeyo's guide for the design, use and maintenance of automatic fire detection systems. Recommended!

7.- How to install a smoke detector at home and what should I look at

One aspect must be highlighted, a automatic fire detection system for a home is simple and easy to install by us, but, in buildings, large premises, offices, warehouses, etc. It will be necessary through professionals. Here the regulations are complex in locations and number of elements (See next section on obligations according to uses).

Here we stop nonsense and directly a good video for install a smoke alarm at home of the Mapfre Foundation:

For a home, they are sold self-adhesive and with two screws, in case it does not stick well.Its installation has no secret, just remember to test it to see if it works.

East alarm system have minimal maintenance, but remember to test if it works from time to time. It should be cleaned at least once a month:

  • Use a soft bristle brush or the brush attachment of a vacuum cleaner to remove dust and cobwebs from the grooves.
  • Clean the cover with a damp cloth and dry it well. Let the light signal show.
  • Remove any insects or cobwebs to avoid creating false fire alarms.

When the regulations require us to have a fire system

In Spain, for a home, flat or house it is not mandatory (Yes in many countries of the European Union). But in residential for homes, which is the majority of cases, the Technical Building Code (CTE) and Royal Decree 513/2017 (Regulation of fire protection facilities) add the obligation when:

  • Home use (Residential buildings), if the evacuation height exceeds 50 meters.
  • Parking use, detection is required for those with an area greater than 500 m2. Also a carbon monoxide (toxic gas) detection system in car parks with more than 5 spaces or more than 100 m2.

Broadly speaking, in the following table we can identify when is a fire system mandatory:

Intended use of the building or establishment Terms
Residential use housing
Fire detection and alarm system.
If the evacuation height exceeds 50 m.
Administrative use Alarm system
Fire detection system.
If the constructed area exceeds 1,000 m2
If the constructed area exceeds 2,000 m2, detectors in high risk areas according to chapter 2 of section 1 of the Basic Fire Safety Document. If it exceeds 5,000 m2, in the entire building.
Residential-public use
Fire detection and alarm system.
If the constructed area exceeds 500 m2
Hospital use
Fire detection and alarm system.
In any case. The system will have connected sensors and manual call points and must allow the transmission of local alarms, general alarms and verbal instructions.
If the building has more than 100 beds. You must have direct telephone communication with the fire service.
Educational use
Alert system.
Smoke presence system.
If the constructed area exceeds 1,000 m2
If the constructed area exceeds 2,000 m2, appliances in high risk areas according to chapter 2 of section 1 of the Basic Fire Safety Document. If it exceeds 5,000 m2, in the entire building.
Commercial use
Alarm system.
Fire detection system.
If the constructed area exceeds 1,000 m2
If the constructed area exceeds 2,000 m2
Public use concurrency
Alarm system.
Smoke detection system.
If the occupancy exceeds 500 people, the system must be capable of broadcasting messages over the public address system.
If the constructed area exceeds 1,000 m2
Use parking
Smoke detection system.
In conventional car parks with a constructed area exceeding 500 m2, robotic car parks will have alarm buttons in any case.

Remember that the Fire Regulations are extensive and constantly changing as shown by the Spanish Society for Fire Protection Tecnifuego, so the table above is indicative. Not to mention that in many cases a safety study + corresponding project is necessary.

By the way, since we are talking about possible damage to the home. We have an extensive article on how to detect damage to houses and structures after earthquake - earthquake.

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