What is a BTU Meter?

A BTU meter is a special instrument that measures the thermal energy transferred in a heating or cooling system. BTU meters are also known as energy meters, heat meters. Commonly used are electromagnetic energy meters and ultrasonic energy meters. It is widely used in online metering of central air-conditioning cooling and heating energy metering and heating network. It can also be used to measure the performance of energy conservation measures or the loss of system efficiency that affects revenue.

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What Is a BTU Meter?

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What is BTU?

BTU (British Thermal Unit). 1BTU is approximately equal to 252.1644 calories (calorie) = 0.293 watt-hour (watt-hour) = 1.055 kilojoules (killojoule)

1 BTU is the amount of heat required to heat 1 pound of pure water from 59 degrees Fahrenheit to 60 degrees Fahrenheit at an atmospheric pressure of 14.696 pounds per square inch. ​​

Btu is British Thermal Unit (British Thermal Unit) and Btu/h is “British Thermal Unit per hour”. Since 1(British Thermal Unit) = 1055.056(Joule), and 1 Watt = 1 Joule/Sec. ​​

So 1 (Btu per second) = 1055.056 (Watts), converting seconds to hours is: 1 BTU per hour = 1055.056/3600 = 0.293071 (Watts). ​​

Therefore, the power of an air conditioner with a (BTU/H) of 10000 is 10000*0.293 = 2.93 (kW).

BTU Meter Working Principle

When the water flows through the system, according to the flow rate given by the flow sensor and the temperature signal of the supply and return water given by the paired temperature sensor, as well as the time that the water flows. Calculate and display the heat energy released or absorbed by the system through the calculator.

Its basic formula is as follows:

BTU Meter Working Principle

In the formula:

Q—the heat released or absorbed by the system, J;
qm flow through heat meter
The mass flow of water, kg/h;
qv is the volume flow of water passing through the heat meter, m5/h;
ρ Density of water passing through the heat meter, ks/m3;
△h—the difference in the enthalpy of water at the inlet and outlet temperatures of the heat exchange system, J/kg;
T a time, h.

From the working principle of the heat meter, it can be seen that the heat meter is mainly divided into three parts: the base meter, the temperature sensor and the totalizer.

The base meter refers to the meter that measures the flow and converts the flow information into electrical signals.

The temperature sensor refers to a sensor that measures the temperature of the supply and return water of the heat exchange system.

The totalizer is a device that integrates and displays heat according to the formula.

Video source: https://www.youtube.com/watch?v=keD50bX1mec

BTU meter calculations are based on the measurement of flow rate and temperature difference in a heat transfer system. We now take a chilled water system as an example, and we want to calculate the amount of energy used for cooling.

Starting Data:

Flow rate of chilled water: 500 gallons per minute (GPM).
Inlet water temperature (before cooling): 70°F.
Outlet water temperature (after cooling): 50°F.

BTU Meter Calculation Steps:

  • Measure Temperature Difference: Calculate the difference in temperature between the inlet and outlet, which is 70°F – 50°F = 20°F.
  • Calculation Formula: The BTU calculation formula is BTU = Flow Rate (in lbs) x Temperature Difference x Specific Heat of Water. The specific heat of water is approximately 1 BTU/lb°F.
  • Convert Flow Rate to Weight: Convert the flow rate from gallons per minute to pounds per minute. Since water weighs about 8.34 pounds per gallon, the conversion for 500 GPM is 500 x 8.34 = 4170 lbs/min.
  • Final BTU Calculation: Plug the values into the formula:BTU = 4170 lbs/min x 20°F x 1 BTU/lb°F, which equals 83,400 BTU/min.

The industrial cooling system uses 83,400 BTUs per minute to cool the machinery and processes.

BTU Measurement System

BTU measurement systems are an important component in the pursuit of energy efficiency and sustainability in heating and cooling systems.

Define BTU measurement system:

BTU measurement systems are an important tool for understanding and managing energy in heating and cooling systems. At its core, the system relies on the British Thermal Unit (BTU), a unit of measurement of heat energy. 1 BTU represents the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit.

Components of a BTU measurement system:

A key component of this system is the BTU meter. Measure the flow rate and temperature difference of a liquid passing through a heat exchanger.

The system includes:

  • Two temperature sensors: installed at the inlet and outlet of the heat exchanger to measure the temperature difference.
  • Flow sensor: This component tracks the flow of liquid through the heat exchanger, which is a key part of energy calculations.
  • Calculator: It processes data from temperature and flow sensors to provide accurate calculations of heat energy transfer.

Applications beyond the basics

BTU measurement systems have uses far beyond basic temperature and flow measurements:

  • Energy Consumption Monitoring: It provides a detailed view of system energy usage, enabling smarter, more cost-effective decisions.
  • HVAC System Optimization: Ensure your heating and cooling systems are running at peak performance by pinpointing inefficiencies.
  • Leak and inefficiency detection: The system can alert on leaks or inefficiencies, preventing energy loss and potential system damage.
  • Improvement identification: It plays a key role in identifying areas where energy consumption can be reduced, promoting sustainable practices.

BTU Meter Types

There are different types of BTU meters, each suited for specific applications and system requirements.

The mechanical heat meter is mainly based on the impeller heat meter. Its working principle is to measure the flow rate of the heat medium by measuring the speed of the impeller, and then measure the heat value.

Turbine Meters: These meters use a rotating turbine to measure the flow rate of the fluid. The turbine’s rotational speed is proportional to the flow rate, providing a direct measurement of energy transfer.

Vortex Meters: Vortex meters detect vortices that are created when a fluid flows past an obstruction. The number of vortices is proportional to the flow rate and is used to calculate energy usage.

The ultrasonic heat meter uses a pair of ultrasonic energy exchange energy to send and receive ultrasonic waves alternately (or simultaneously). By observing the propagation time difference between the forward and reverse flow of the ultrasonic waves in the medium, the flow rate of the fluid is indirectly measured. The flow rate is then used to calculate the flow rate. Then calculate the heat value.

Clamp-On Meters: These meters use external sensors that are clamped onto the pipe. They measure the flow rate using ultrasonic signals, which is non-intrusive and causes no disruption to the system.

Inline Meters: Inline ultrasonic meters are installed within the pipeline. They offer high accuracy and are ideal for systems where a non-intrusive setup is not critical.

The main features of the ultrasonic heat meter are that there is no mechanical impeller rotation and no mechanical wear. The maintenance cost is low for later use. The service life is much longer than that of the mechanical heat meter. The flow measurement accuracy is high and the measurement reliability is good.

Electromagnetic heat meter is a measuring instrument that measures the heat released by the heat transfer fluid in the heat exchange system. A high-precision and high-reliability electromagnetic flowmeter is used as a flow meter. At the same time, a high-precision, high-stability platinum heat meter is used The resistance is used for temperature measurement. The thermal energy meter has excellent measurement performance.

At present, the electromagnetic heat meters used in the market are mainly integrated electromagnetic heat meters. Its main feature is to improve the measurement accuracy. It increases the reliability and stability of the product. It is free of debugging and maintenance. It is easy to install, But the price is relatively high.

Orifice Plate Meters: These meters use an orifice plate to create a pressure drop, which is measured to determine the flow rate.

Venturi Meters: Similar to orifice plate meters, but use a venturi tube to create a pressure drop. They are more efficient and have a lower pressure drop compared to orifice plates.

BTU Meter for Chilled Water

A BTU (British Thermal Unit) meter for chilled water is a specialized device used in cooling systems, particularly in HVAC (Heating, Ventilation, and Air Conditioning) applications. Its primary function is to measure the energy consumed in cooling processes by calculating the heat removed from the chilled water

The BTU meter consists of a flow measurement sensor, two temperature sensors, and a microprocessor-based energy calculator.

The flow sensor should be installed in the chilled water return line, and the chilled water flow direction should be installed in a vertical or horizontal position. Two temperature sensors, one sensor is installed on the oil return line. The second sensor is installed on the water supply line. The thermal energy transferred from the cooling water to the consumer over a specified period of time is proportional to the temperature difference between the flow and return flow and the amount of cooling water flowing through.

Sino-Inst offers two types of BTU meters, one with ultrasonic measurement technology (ultrasonic BTU meter) and the other with electromagnetic measurement technology (electromagnetic BTU meter).

BTU meters are widely used in:

  • Building HVAC Systems: In large buildings, accurate measurement of chilled water energy use is crucial for efficient system operation and cost allocation.
  • Industrial Cooling Processes: Industries that require precise temperature control rely on these meters for energy management and to ensure optimal operation of cooling equipment.
  • District Cooling Systems: They are also essential in district cooling systems, where chilled water is supplied to multiple buildings from a central plant.

Benefits of Using BTU Meters in Chilled Water Systems:

  • Energy Efficiency: By providing accurate energy usage data, these meters help in optimizing the operation of cooling systems, leading to energy savings.
  • Cost Allocation: In multi-tenant buildings, BTU meters enable fair billing based on actual energy usage for cooling.
  • System Monitoring and Maintenance: Regular readings from these meters can indicate system performance and help in early detection of issues.

Whether in a commercial, industrial or residential environment, a chilled water system’s BTU meter is an important tool in managing the cooling process.

BTU Meter Installation

BTU Meter Installation

The installation requirements for electromagnetic heat meters and ultrasonic heat meters vary.

Personally recommend the Clamp-On ultrasonic heat meter. Because the installation is the easiest.

Clamp-On ultrasonic sensors and external clamp-on temperature sensors are available. Installation is simple and low cost.

About the installation of electromagnetic heat meter. You May refer to the following PDF.

bTU meter vs flow meter

Both BTU meters and flow meters have their own importance. BTU meters help keep heating and cooling systems efficient, while flow meters ensure the correct movement of fluids through various systems.

FeatureBTU MeterFlow Meter
Primary FunctionMeasures energy usage in heating or cooling systems.Measures the volume or speed of a fluid (like water or gas).
Measurement TypeCalculates energy by assessing temperature change and flow rate.Measures the amount or flow rate of the fluid passing through it.
Typical Use CasesUsed in HVAC systems (heating, ventilation, and air conditioning), for efficiency monitoring in heating or cooling processes.Used in various industries, including water treatment, chemical processing, and residential water systems.
Key Information ProvidedProvides data on heat energy added or removed, crucial for energy management.Provides data on the quantity or speed of fluid, important for volume control and monitoring.
ComplexityGenerally more complex, as it combines flow measurement with thermal energy calculation.Simpler in operation, focusing solely on fluid flow measurement.
ImportanceEssential for energy efficiency and cost management in temperature control systems.Critical for managing and monitoring fluid flow in diverse applications.

Understanding the differences can help you choose the right tool for the job. If you need to know how well your heating or cooling is working, a BTU meter is your first choice. But if you just need to know how much water or gas is flowing, then a flow meter is what you need.


1 btu per (square meter) =1 055.05585 kg / s2


BTU = Flow Rate In GPM (of water) x (Temperature Leaving Process – Temperature Entering Process) x 500.4*Formula changes with fluids others than straight water.

BTU Calculator Tool

BTU is short for British Thermal Unit, a unit of measurement that shows just how much energy your air conditioner uses to remove heat from your home within an hour. It may seem overly technical, but BTU is an important metric that can help you determine the kind of air conditioner you need for a home your size.

Flow meters measure flow, and heat meters measure heat. The heat meter consists of an integrator (calculator), a flow meter, and a pair of temperature sensors. The first detection is the supply/return water temperature and flow rate, and then the integrator is used to calculate the heat. The basic principle is Q=Cm△t.

Compared with thermistors, platinum resistors have the advantages of accurate measurement and small resistance drift. Therefore, general heat meters use pairs of platinum resistors as temperature sensors. Usually there are PT100, PT500, and PT1000, with PT1000 being the most common (i.e. At 0℃, the resistance value is 1000Ω)

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Sino-Inst offers over 10 BTU Meter products. About 60% of these are ulrtasonic flow meters. 40% are magnetic meters.

A wide variety of BTU Meter options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of BTU Meters, located in China.

The top supplying country is China (Mainland), which supply 100% of the BTU Meter respectively.

You can ensure product safety by selecting from certified suppliers, with ISO9001, ISO14001 certification.

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