What Are Heat Detectors? Don’t Wait for Smoke

When it comes to fire safety, there are various types of detectors available that can help in the early detection of a fire. One such type is heat detectors. What are heat detectors?

Well, we’ll get to that in a moment. But first, it’s important to understand why early detection is crucial in fire safety. In this blog post, we’ll explore the different types of detectors and their importance in fire safety. So, let’s dive in.

What Are Heat Detectors?

Heat detectors are devices that are designed to detect heat and changes in temperature.

They are commonly used in commercial and industrial settings, where there may be a higher fire risk.

Heat detectors are essential to fire detection and alarm systems, as they provide an early warning of a potential fire.

There are two main types of heat detectors: fixed temperature and rate-of-rise. Fixed temperature detectors are designed to trigger an alarm when the temperature reaches a certain level.

On the other hand, rate-of-rise detectors are designed to detect rapid increases in temperature and trigger an alarm when the temperature rises too quickly.

How Do Heat Detectors Work

Heat detectors work by detecting changes in temperature or reaching a predetermined temperature threshold, which triggers an alarm. There are typically two types of heat detectors: fixed-temperature heat detectors and rate-of-rise heat detectors.

Fixed temperature heat detectors: These heat detectors have a set temperature threshold, and when the temperature rises to that threshold, the heat detector triggers an alarm.

They are designed to detect a rapid temperature rise and are commonly used in environments where fires can develop quickly, such as kitchens, boiler rooms, or garages.

Rate-of-rise heat detectors: These heat detectors are designed to detect a rapid rate of temperature rise rather than a specific temperature threshold.

They have a built-in sensor that measures the rate of temperature increase, and if the rate exceeds a predetermined threshold, the heat detector triggers an alarm.

Rate-of-rise heat detectors are typically used where fires can start from small smoldering fires or slow heat build-ups, such as storage areas or attics.

Heat detectors are typically hardwired or connected to a fire alarm control panel (FACP) and can be integrated into a larger fire detection and suppression system.

When the heat detector is triggered, it sends a signal to the FACP, which activates the fire alarm and initiates appropriate response actions, such as sounding alarms, notifying emergency services, or activating fire suppression systems.

Why Are Heat Detectors Important?

Heat detectors are important for fire detection and safety for several reasons:

Early warning of fires: Heat detectors can provide early warning of fires by sensing a rapid rise in temperature, which may indicate the presence of a fire.

They can trigger an alarm when the temperature exceeds a pre-set threshold or rises at a rate higher than a pre-set threshold.

This early warning can allow people to evacuate the premises, call for help, and take appropriate action to mitigate the fire hazard.

Reliable fire detection in challenging environments: Heat detectors are designed to operate in environments where smoke detectors may not be suitable due to the presence of dust, steam, or other conditions that can cause false alarms.

For example, heat detectors can be used in areas such as kitchens, boiler rooms, garages, or workshops, where smoke detectors may be prone to false alarms due to cooking activities, high humidity, or other factors.

Heat detectors provide reliable fire detection in challenging environments where other types of detectors may not be effective.

Complementary fire detection coverage: Heat detectors are often used in conjunction with smoke detectors to provide comprehensive fire detection coverage.

Smoke detectors are effective in detecting fires that produce smoke, while heat detectors are designed to detect fires that may not produce significant smoke, such as fast-burning or heat-driven fires.

Using both smoke and heat detectors in a fire protection system can enhance the overall fire detection capabilities and improve the safety of occupants.

Compliance with building codes and regulations: Heat detectors may be required by building codes and regulations in certain areas or applications.

For example, in industrial or commercial settings, heat detectors may be required by local fire codes or insurance regulations to provide adequate fire detection coverage.

Compliance with these codes and regulations is essential to ensure the safety of occupants, protect property, and meet legal requirements.

Customizable for different environments: Heat detectors come in different types and configurations, such as fixed temperature, rate-of-rise, combination, and line-type heat detectors, which can be chosen based on the specific requirements of the environment.

This allows for customization and flexibility in designing fire protection systems that meet different areas or applications’ unique fire detection needs.

What Triggers Heat Detectors?

significant changes in temperature trigger heat detectors. This can be caused by a number of factors, including:

Flames – Flames produce a significant amount of heat, which can cause a heat detector to trigger.

Electrical Malfunctions – Electrical malfunctions can cause electrical equipment to overheat and trigger a heat detector.

Cooking – Cooking can produce a significant amount of heat and if left unattended, can cause a heat detector to activate.

Smoking – Smoking can cause a heat detector to activate due to the heat produced by the cigarette.

Heating Equipment – Heating equipment such as space heaters can overheat and trigger a heat detector.

Once a heat detector is triggered, it sends a signal to the central monitoring station, which alerts the appropriate authorities. This provides valuable time for individuals to evacuate the building and for the fire department to arrive.

Types Of Heat Detectors

There are several types of heat detectors commonly used in fire protection systems. These include:

Fixed Temperature Heat Detectors: These heat detectors operate based on a pre-set threshold temperature.

They typically have a fusible element or a bi-metallic strip designed to melt or expand when the ambient temperature rises above the pre-set threshold.

Once the fusible element melts or the bi-metallic strip expands, it triggers the alarm, indicating the presence of a fire.

Fixed temperature heat detectors are simple and cost-effective, and they are commonly used in environments where the temperature is expected to rise rapidly in case of a fire.

Rate-of-Rise Heat Detectors: Rate-of-rise heat detectors are designed to trigger an alarm when the temperature rises at a rate higher than a pre-set threshold.

These detectors typically have a built-in temperature sensor that measures the change in temperature over a short period.

If the temperature rises at a rate higher than the pre-set threshold, the detector triggers the alarm.

Rate-of-rise heat detectors are useful in environments where a fire can spread quickly, such as in areas with combustible materials or flammable liquids.

Combination Heat Detectors: Combination heat detectors combine the features of fixed temperature and rate-of-rise heat detectors.

They typically have a fusible element or a bi-metallic strip for fixed temperature detection and a built-in temperature sensor for rate-of-rise detection.

If the ambient temperature rises above the pre-set threshold or rises at a rate higher than the pre-set threshold, the detector triggers the alarm.

Combination heat detectors provide a dual-detection capability, offering increased reliability and flexibility in fire detection.

Line-Type Heat Detectors: Line-type heat detectors consist of a heat-sensitive cable or wire that can be installed in specific areas, such as along the ceiling or walls.

The cable or wire is designed to expand when the temperature rises above a pre-set threshold, which triggers the alarm.

Line-type heat detectors may use different technologies, such as pneumatic, electronic, or digital, to detect the change in temperature and trigger the alarm.

Line-type heat detectors are commonly used in areas where traditional point-type heat detectors may be impractical or where coverage along a specific linear path is required, such as in cable trays, conveyor belts, or ducts.

Spot-Type Infrared Heat Detectors: Spot-type infrared heat detectors use infrared technology to detect the heat emitted by a fire.

They typically have a built-in infrared sensor that measures the amount of infrared radiation emitted by an object, such as a fire, in its field of view.

The detector triggers the alarm when the infrared radiation exceeds a pre-set threshold.

Spot-type infrared heat detectors are commonly used in environments where smoke or dust may be present, as they are less prone to false alarms compared to smoke detectors.

Heat Detector Advantages And Disadvantages

Heat detectors have both advantages and disadvantages as fire detection devices. Here are some of them:

Advantages of Heat Detectors:

Reliable detection of high heat: Heat detectors are designed to detect a rapid temperature rise, which is typically associated with a fire.

They do not generate false alarms due to smoke or other environmental factors, making them reliable in environments where smoke detectors may not be suitable, such as areas with high dust, steam, or other airborne particles.

Durability: Heat detectors are generally durable and less susceptible to damage or wear and tear compared to other fire detectors, such as smoke detectors.

They are typically less sensitive to environmental factors and can withstand harsh conditions, making them suitable for use in industrial or outdoor environments.

Cost-effective: Heat detectors are generally less expensive than other types of fire detectors, such as smoke or flame detectors.

They are a cost-effective option for fire detection in areas where smoke detectors may not be practical or effective.

Simple installation: Heat detectors are relatively simple and do not require extensive wiring or complicated setup.

They can be easily installed in areas where a rapid temperature rise is expected, such as kitchens, utility rooms, or mechanical rooms.

Disadvantages of Heat Detectors:

Delayed detection of smoldering fires: Heat detectors may not detect smoldering fires or fires with slow heat buildup, as they rely on a rapid rise in temperature to trigger an alarm.

This can delay fire detection and response, giving the fire more time to spread before being detected.

Lack of early warning: Heat detectors do not provide early warning of fires that produce smoke or toxic gases before a rapid rise in temperature occurs.

This means that occupants may not be alerted to a fire in its early stages, potentially reducing the time available for evacuation.

Limited detection range: Heat detectors have a limited detection range, typically within a few feet or meters, depending on the type of heat detector. This means that they may not be suitable for large areas or spaces where a fire may start in a remote location.

Lack of specificity: Heat detectors do not provide information about the type or location of a fire, as they only detect a rapid rise in temperature.

This can make determining the exact location or nature of the fire challenging, which may impact firefighting efforts.

Difference Between Heat Detector VS Smoke Detector

Heat and smoke detectors are both types used in fire protection systems, but they operate based on different principles and have distinct features.

Here are the key differences between heat detectors and smoke detectors:

Detection Principle: Heat detectors detect temperature changes, whereas smoke detectors detect the presence of smoke particles in the air.

Heat detectors are triggered by a change in temperature that exceeds a pre-set threshold. In contrast, smoke detectors are triggered by smoke particles in the air that interrupt or scatter a light beam, ionize air particles, or change the electrical conductivity of the air.

Fire Detection Capability: Heat detectors are generally slower in detecting fires than smoke detectors.

Heat detectors are effective in detecting fires with a significant rise in temperature, such as in fast-burning fires or fires involving flammable liquids.

Smoke detectors, on the other hand, are typically more sensitive and can detect fires early when smoke is present, even before a significant increase in temperature occurs.

Smoke detectors are effective in detecting slow-burning, smoldering, and fires that produce a significant amount of smoke, such as fires involving upholstered furniture, mattresses, or electrical wiring.

False Alarm Potential: Heat detectors are generally less prone to false alarms than smoke detectors.

Heat detectors are triggered by a change in temperature, which is less likely to be caused by non-fire-related factors, such as dust, steam, cooking fumes, or aerosols.

On the other hand, smoke detectors can be triggered by non-fire-related factors, which may result in false alarms.

However, modern smoke detectors often come with advanced features, such as dual-sensing technology or algorithms, to reduce false alarms caused by non-fire-related factors.

Installation Requirements: Heat detectors and smoke detectors may have different installation requirements.

Heat detectors are typically installed where the temperature is expected to rise rapidly in case of a fire, such as near heat sources, electrical panels, or mechanical equipment.

Smoke detectors, on the other hand, are typically installed in areas where smoke is likely present in the early stages of a fire, such as in hallways, bedrooms, living rooms, and common areas.

The placement and spacing requirements for heat and smoke detectors may vary depending on the specific type of detector, the environment, and local building codes and regulations.

Types and Variations: Heat detectors and smoke detectors come in various types and variations, such as fixed temperature heat detectors, rate-of-rise heat detectors, combination heat detectors, spot-type smoke detectors, photoelectric smoke detectors, ionization smoke detectors, and dual-sensor smoke detectors.

Each type of detector has its own strengths and weaknesses, and the choice of detector type depends on the specific requirements of the environment, the fire detection needs, and compliance with applicable building codes and regulations.

Where To Install Heat Detectors In A House

Heat detectors are typically installed in areas where the temperature is expected to rise rapidly in case of a fire. Here are some common locations where heat detectors can be installed in a house:

Kitchen: Heat detectors can be installed in the kitchen, where cooking activities can potentially lead to a fire.

They should be installed away from the stove or oven but still close enough to detect a rapid rise in temperature in case of a fire.

Utility rooms: Heat detectors can be installed in utility rooms where there may be heat-producing appliances or equipment, such as water heaters, boilers, furnaces, or electrical panels.

They should be installed near these appliances or equipment but away from direct heat sources to avoid false alarms.

Mechanical rooms: Heat detectors can be installed in mechanical rooms with heating, ventilation, and air conditioning (HVAC) systems or other heat-generating equipment.

They should be installed in areas where a rapid temperature rise can be detected in case of a fire.

Garage: Heat detectors can be installed in garages where vehicles, tools, or other combustible materials can pose a fire risk.

They should be installed away from direct heat sources but still close enough to detect a significant rise in temperature in case of a fire.

Attic or crawl spaces: Heat detectors can be installed in attics or crawl spaces where electrical wiring, insulation, or other combustible materials can catch fire.

They should be installed in areas where a rapid rise in temperature can be detected in case of a fire.

Other high-risk areas: Heat detectors can also be installed in other high-risk areas of the house, such as near wood-burning stoves, fireplaces, or chimneys, or in areas where flammable liquids or gases are stored, such as near propane tanks or fuel storage areas.

What Temperature Should Heat Detector Be?

The National Fire Protection Association (NFPA) recommends installing heat detectors in areas where smoke detectors may not be effective, such as in garages or attics.

The NFPA also recommends installing heat detectors in areas where the temperature may exceed 100°F (37.8°C), such as in boiler rooms, mechanical rooms, and laundry rooms.

In general, most fixed temperature heat detectors are set to trigger an alarm at temperatures between 135°F (57.2°C) and 190°F (87.8°C).

However, it’s important to note that this range may vary depending on the specific heat detector used and the manufacturer’s recommendations.

 

Now, why is it so important to get the temperature setting right?

The answer is simple: if the heat detector is set too low, it may trigger false alarms, which can cause occupants to become complacent and ignore future alarms.

On the other hand, if the heat detector is set too high, it may not trigger an alarm until it’s too late, putting lives and property at risk.

What To Do If Your Heat Detector Goes Off?

If your heat detector goes off, it indicates that there may be a fire or a significant rise in temperature in the area where the heat detector is installed.

Here are the steps to take if your heat detector goes off:

Stay calm: It’s important to stay calm and not panic. Stay focused and composed to handle the situation effectively.

Evacuate immediately: If you are in a residential or commercial building, evacuate the premises immediately. Follow the established evacuation plan and proceed to the designated meeting point or a safe location outside the building.

Call emergency services: Call emergency services, such as the fire department, using a phone that is located outside the building or at a safe distance from the fire.

Provide your name, location, and details about the situation, including the fact that the heat detector has gone off.

Do not delay to investigate: Do not delay to investigate the cause of the heat detector going off or attempt to extinguish the fire yourself, as your safety should be the top priority.

Leave firefighting to trained professionals.

Close doors behind you: As you evacuate, close doors behind you to help prevent the spread of fire and smoke. Do not use elevators during evacuation, and use stairs if they are safe to do so.

Follow emergency procedures: Follow any established emergency procedures or protocols in place, such as using fire extinguishers or activating the fire alarm system, if it is safe and part of your designated role.

Wait for emergency services: Once you have safely evacuated, wait for emergency services to arrive and provide them with any additional information that may be helpful, such as the location of the fire or any other relevant details.

Do not re-enter the building: Do not re-enter the building until it has been deemed safe by the fire department or other emergency personnel.

Review and update fire safety measures: After the incident, review and update your fire safety measures, including the maintenance and testing of heat detectors, as well as other fire detection and suppression systems in your premises, to ensure they are in proper working condition.

Conclusion

Heat detectors are important fire detection devices that can provide early warning of fires in environments where smoke detectors may not be suitable due to dust, moisture, or other factors.

They work by detecting a rapid rise in temperature or reaching a predetermined temperature threshold, which triggers an alarm.

Heat detectors have advantages such as their ability to work in harsh environments and their low false alarm rates.

However, they may have limitations in detecting smoldering fires or fires in their early stages that produce little heat. Proper installation, regular maintenance, and adherence to fire safety protocols are essential for the effective use of heat detectors.