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Fan Coil Unit Sensor Calibration London

In the bustling city of London, maintaining optimal indoor thermal comfort in commercial buildings is of paramount importance. To achieve this, the calibration of fan coil unit sensors plays a crucial...

In the bustling city of London, maintaining optimal indoor thermal comfort in commercial buildings is of paramount importance. To achieve this, the calibration of fan coil unit sensors plays a crucial role. Fan coil unit sensor calibration in London ensures accurate temperature and humidity measurements throughout a building, allowing for precise control and efficient energy management. This article discusses the significance of sensor calibration, the potential consequences of neglecting this vital task, and the benefits it brings to maintaining a comfortable and productive working environment in the heart of the busy capital.

What is a Fan Coil Unit?

Definition and Function

A fan coil unit (FCU) is a mechanical device used in HVAC systems to regulate the temperature and airflow within a space. It consists of a fan, a heating or cooling coil, and various sensors, including temperature and moisture sensors. The FCU is typically installed in individual rooms or zones and is connected to a centralized control system. It works by drawing air from the room, passing it over the coil to either heat or cool it, and then returning the conditioned air back into the room.

Types of Fan Coil Units

There are different types of fan coil units available to meet the specific requirements of different spaces. The most common types include:

  1. Standard Fan Coil Units: These units can only provide cooling or heating, depending on the coil installed.
  2. Four-Pipe Fan Coil Units: These units have separate coils for cooling and heating, allowing for simultaneous operation.
  3. Ceiling Mounted Fan Coil Units: As the name suggests, these units are mounted on the ceiling and are often used in commercial settings.
  4. Ducted Fan Coil Units: These units are connected to ductwork and provide conditioned air to multiple areas or rooms.
  5. High-Static Pressure Fan Coil Units: These units are designed to deliver conditioned air over longer distances and are used in larger spaces.

Each type of fan coil unit has its own advantages and considerations based on factors such as the size of the space, the cooling or heating requirements, and the desired flexibility in operation.

Importance of Sensor Calibration

Ensuring Accuracy

Sensor calibration is crucial when it comes to maintaining accurate temperature and moisture measurements in a fan coil unit. Calibrated sensors provide reliable data, which is essential for controlling the HVAC system and achieving the desired comfort levels. By ensuring accuracy through calibration, you can trust that the information provided by the sensors is correct and make informed decisions regarding temperature adjustments and energy management.

Optimizing Energy Efficiency

Properly calibrated sensors allow for optimized energy efficiency in fan coil units. When the sensors accurately detect temperature and moisture levels, the HVAC system can adjust its operation accordingly. This includes regulating the fan speed, controlling the heating or cooling output, and optimizing the overall energy consumption. By calibrating the sensors regularly, you can avoid energy wastage and achieve significant cost savings.

Preventing Equipment Damage

Inaccurate sensor readings can lead to improper operation of the fan coil unit, potentially causing equipment damage. For example, if the temperature sensor is not properly calibrated, it may not accurately detect excessive heat buildup, leading to a failure to activate the cooling coil. This can result in the overheating of the fan coil unit, damaging the components and reducing the lifespan of the equipment. Regular sensor calibration helps prevent such issues by ensuring that the sensors accurately detect and respond to changes in temperature and moisture levels.

Maintaining Comfort Levels

Fan coil units are designed to provide comfort by controlling the temperature and airflow in a room. However, if the sensors are not calibrated correctly, the system may not achieve the desired comfort levels. Inaccurate temperature readings can result in overheating or insufficient cooling, leading to discomfort for the occupants. Additionally, inaccurate moisture readings can affect humidity levels, causing discomfort or even health issues. Proper sensor calibration is essential for maintaining the comfort and well-being of the individuals occupying the space.

Factors Affecting Fan Coil Unit Sensor Calibration

Temperature Variations

Temperature variations in the room can affect the accuracy of the fan coil unit sensors. For example, if the sensors are located near heat sources such as radiators or direct sunlight, they may provide inaccurate readings. It is important to consider the placement of the sensors and their proximity to temperature fluctuations when calibrating them.

Airflow Restrictions

Restricted or inadequate airflow can also impact sensor calibration. If the airflow around the sensors is obstructed by furniture, objects, or improperly sized air vents, the sensors may not receive accurate readings. It is crucial to ensure proper airflow around the sensors to maintain their calibration and achieve reliable temperature and moisture measurements.

Filter Blockages

Dirty or clogged air filters can affect the airflow and the accuracy of the sensors. When the air filters are blocked, the fan coil unit may struggle to draw in the air, leading to inefficient operation and potential sensor inaccuracies. Regular cleaning and maintenance of the air filters are essential to prevent filter blockages and ensure the proper functioning of the sensors.

Dirty Coils

Dirty coils can negatively impact the performance of the fan coil unit and its sensors. Accumulated dirt and debris on the coils can hinder the heat transfer process, resulting in temperature fluctuations and inaccurate readings. Regular cleaning and inspection of the coils help maintain optimal performance and ensure accurate sensor calibration.

Proximity to Heat Sources

The proximity of the sensors to intense heat sources can interfere with their calibration and accuracy. Heat sources such as hot water pipes, electrical equipment, or equipment generating excessive heat should be taken into account when positioning the sensors. Maintaining sufficient distance between the sensors and these heat sources is essential for accurate calibration.

Humidity Levels

Humidity levels can affect the accuracy of moisture sensors in fan coil units. High humidity can cause condensation on the sensors, leading to inaccurate moisture readings. Conversely, low humidity levels can affect the performance of the sensors, resulting in incorrect measurements. Considering the ambient humidity levels and properly calibrating the moisture sensors are important for accurate humidity control and comfort.

Common Sensor Calibration Issues


Under-calibration refers to a situation where the sensors in a fan coil unit provide readings that are lower than the actual temperature or moisture levels. This can lead to incorrect control of the HVAC system, resulting in inadequate cooling or heating. Under-calibration can occur due to factors such as sensor drift, improper initial calibration, or environmental changes not accounted for during calibration.


Over-calibration, on the other hand, occurs when the sensors provide readings that are higher than the actual temperature or moisture levels. This can lead to excessive cooling or heating and potentially uncomfortable conditions for the occupants. Over-calibration can be caused by similar factors as under-calibration, such as sensor drift or changes in the environment.

Inaccurate Readings

Inaccurate readings can occur due to various factors, including sensor malfunction, physical damage to the sensors, or improper calibration techniques. Inaccurate readings can lead to inefficient HVAC system operation and discomfort for the occupants. Regular calibration and maintenance of the sensors are important to minimize inaccurate readings and ensure reliable performance.

Sensor Malfunction

Sensor malfunction can happen as a result of wear and tear, electrical issues, or physical damage. A malfunctioning sensor may provide erratic readings or stop functioning altogether. It is important to regularly inspect the sensors for signs of damage or malfunction and replace them if necessary. Malfunctioning sensors can affect the overall performance of the fan coil unit and compromise the accuracy of temperature and moisture control.

Inconsistent Performance

Inconsistent performance of the fan coil unit sensors can occur if the calibration settings are not maintained properly or if the sensors are affected by external factors such as environmental changes or interference. Inconsistent performance can lead to temperature fluctuations, inefficient operation, and discomfort for the occupants. Regular calibration and thorough troubleshooting are essential for addressing and resolving inconsistent sensor performance.

The Calibration Process

Identifying Sensor Locations

Before starting the calibration process, it is important to identify the locations of the sensors in the fan coil unit. The most common sensor locations include the supply air temperature sensor, return air temperature sensor, discharge air temperature sensor, and moisture sensor. These sensors are strategically placed to provide accurate temperature and moisture measurements for proper control of the HVAC system.

Locating Calibration Instructions

Each fan coil unit model may have specific calibration instructions provided by the manufacturer. It is important to locate these instructions, either in the unit’s manual or by contacting the manufacturer or a professional service provider. The calibration instructions will outline the specific steps and settings required for calibrating the sensors in the fan coil unit.

Preparing for Calibration

Before starting the calibration process, it is crucial to ensure that the fan coil unit is turned off and disconnected from the power source. This ensures safety during the calibration process and prevents any potential damage to the unit. Additionally, it is important to gather the necessary tools and equipment for calibration.

Tools and Equipment Needed

The specific tools and equipment needed for sensor calibration may vary depending on the fan coil unit model and calibration instructions. However, some common tools include a screwdriver for accessing the sensors, a multimeter for measuring voltage and resistance, and a calibration device or software for adjusting the sensor settings. It is important to ensure that the tools and equipment are in proper working condition and suitable for the calibration process.

Adjusting Calibration Settings

Once all the preparations have been made, the calibration process can begin. Following the manufacturer’s instructions, the sensor calibration settings are adjusted using the appropriate tools or software. This may involve adjusting the voltage or resistance values for temperature sensors or modifying the sensitivity or threshold for moisture sensors. The calibration process should be carried out carefully and accurately to ensure precise sensor readings.

Professional Sensor Calibration Services

Benefits of Hiring Professionals

While DIY calibration is possible, there are several benefits to hiring professionals for fan coil unit sensor calibration:

  1. Expert Knowledge and Experience: Professional calibration technicians have specialized knowledge and experience in calibrating a wide range of sensors and HVAC systems. They understand the complexities involved and can ensure accurate calibration based on the specific requirements of your fan coil unit.
  2. Time and Cost Savings: Hiring professionals saves you time and effort by eliminating the need for extensive research, tool gathering, and the trial-and-error process that may come with DIY calibration. Additionally, professionals can complete the calibration process efficiently, minimizing downtime and potential disruptions to your HVAC system operation.
  3. Safety and Compliance: Sensor calibration can involve working with electrical components and potentially hazardous situations. Professional technicians are trained to follow safety protocols and ensure compliance with relevant regulations. This minimizes the risk of accidents or damage to the fan coil unit during the calibration process.
  4. Long-Term Performance: Professionals can provide regular maintenance and monitoring services along with calibration to ensure long-term performance and reliability of your fan coil unit. They can identify any potential issues, address them promptly, and provide recommendations for preventive measures to optimize the performance of your HVAC system.

DIY Sensor Calibration Steps

Gathering Necessary Tools

For those who choose to undertake sensor calibration themselves, it is important to gather the necessary tools and equipment beforehand. As mentioned earlier, the specific tools required may vary depending on the fan coil unit model and calibration instructions. It is advisable to review the instructions and ensure that you have the appropriate tools for the calibration process.

Understanding Calibration Parameters

Before starting the calibration process, it is crucial to have a thorough understanding of the calibration parameters specific to your fan coil unit. These parameters include voltage or resistance values for temperature sensors and sensitivity or threshold values for moisture sensors. Understanding these parameters ensures accurate calibration and prevents potential errors during the process.

Following Safety Precautions

When conducting DIY sensor calibration, it is important to follow safety precautions to prevent any accidents or damage. This includes turning off the fan coil unit and disconnecting it from the power source, wearing appropriate personal protective equipment, and handling the sensors and tools with care. If you are unsure about any safety measures, it is advisable to seek professional assistance.

Calibrating Temperature Sensors

To calibrate temperature sensors, the first step is to access the sensors in the fan coil unit. This typically involves removing the cover or accessing the internal components. Using a multimeter, the voltage or resistance values of the sensors are measured and compared to the desired calibration parameters. Adjustments are made using the appropriate tools or calibration software until the sensors provide accurate temperature readings.

Calibrating Moisture Sensors

Calibrating moisture sensors follows a similar process to temperature sensors. The sensors are accessed and their sensitivity or threshold values are measured using the appropriate tools. These values are then adjusted according to the desired calibration parameters until the sensors provide accurate moisture readings. It is important to ensure that the moisture sensors are free from any moisture or dirt that could affect their performance.

Troubleshooting Common Calibration Problems

Sensor Inaccuracy

If the calibrated sensors continue to produce inaccurate readings even after calibration, it may indicate a deeper issue with the sensors or the fan coil unit itself. In such cases, consulting a professional technician or contacting the manufacturer for troubleshooting and repair guidance is recommended. They can assess the problem and provide the necessary solutions to address the sensor inaccuracy.

Sensor Drift

Sensor drift refers to the gradual shift in sensor readings over time, even after calibration. This can occur due to environmental changes, wear and tear, or the aging of the sensors. To minimize sensor drift, regular sensor calibration, maintenance, and monitoring are necessary. This helps identify any signs of drift early on and allows for prompt adjustments and recalibration as needed.

Calibration Drift

Calibration drift occurs when the calibration settings of the sensors change over time, affecting their accuracy. This can happen due to factors such as aging components, electrical fluctuations, or environmental changes. Regular calibration checks and adjustments are essential to address calibration drift and maintain accurate sensor readings. Professional technicians can provide guidance and support in identifying and rectifying calibration drift.

Sensor Compatibility Issues

In some cases, sensor compatibility issues may arise when attempting to calibrate sensors in a fan coil unit. This can be due to differences in sensor technology, model specifications, or communication protocols. When faced with compatibility issues, consulting the fan coil unit manufacturer or a professional technician can help identify suitable sensor options or provide recommendations for resolving the compatibility issues.

Interference and Signal Loss

Interference and signal loss can impact sensor calibration and performance. This can occur due to electromagnetic interference from nearby electronic devices, inadequate grounding, or poor wiring connections. To prevent interference and signal loss, it is important to ensure proper installation and wiring of the sensors. Consulting a professional technician can help identify and mitigate any interference issues.

Regular Maintenance and Monitoring

Cleaning and Inspecting Sensors

Regular cleaning and inspection of the sensors in a fan coil unit are essential for maintaining accurate calibration and performance. Dust, dirt, and debris can accumulate on the sensors over time, affecting their accuracy and responsiveness. Cleaning the sensors using appropriate methods and materials, such as compressed air or gentle cleaning solutions, helps ensure reliable sensor readings.

Replacing and Upgrading Sensors

Over time, sensors may become worn out, damaged, or outdated, affecting their calibration and performance. Regular inspection allows for the identification of any sensor issues that require replacement or upgrading. It is important to consult with a professional technician to ensure the selection of suitable replacement sensors or upgrades that are compatible with the fan coil unit.

Monitoring Performance Metrics

Monitoring the performance metrics of a fan coil unit is crucial for identifying any potential issues and ensuring optimal operation. This includes regularly checking and recording temperature readings, airflow rates, energy consumption, and other relevant metrics provided by the sensors. Monitoring performance metrics allows for timely detection of any deviations or abnormalities, enabling prompt troubleshooting and maintenance.

Reviewing Calibration Logs

Maintaining a log of calibration activities is important for tracking the calibration history of the fan coil unit sensors. This log should include information such as the date of calibration, calibration settings, any adjustments made, and the condition of the sensors. Reviewing calibration logs helps identify any trends, patterns, or correlations that may affect the performance of the sensors and the fan coil unit.

Implementing Preventive Measures

To ensure the long-term performance and reliability of the fan coil unit sensors, it is important to implement preventive measures based on the insights gained from regular maintenance, monitoring, and calibration activities. This may include adjusting environmental conditions, addressing potential sources of interference, or upgrading components. Implementing preventive measures helps minimize sensor issues and extends the lifespan of the fan coil unit.


Fan coil unit sensor calibration is vital for accurate temperature and moisture control, energy efficiency, equipment protection, and maintaining comfort levels in HVAC systems. Understanding the importance of calibration, the factors affecting it, and the common issues that may arise allows for proactive measures to be implemented. Whether through professional services or DIY calibration, regular calibration and maintenance of the sensors ensure optimal performance and long-term reliability of fan coil units. By prioritizing sensor calibration, you can achieve efficient HVAC system operation, reduced energy consumption, improved occupant comfort, and extended equipment lifespan.

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