What is a BTU Meter?

BTU meters are flow meters with temperature sensors added to measure the energy consumption of any liquid 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.

What Is a BTU Meter?

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 Types

The flow sensor is the most important part of the heat meter and the most sensitive component. The classification of the heat meter actually refers to the classification of the flow sensor. Flow sensors can be divided into three categories: mechanical, ultrasonic and electromagnetic according to their measurement principles.

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.

According to the internal structure classification, it is divided into single-fluid type and multi-fluid type. Among them, the single-fluid type has a short impeller life due to uneven water flow.

According to the different forms of impellers, it is divided into screw type and rotor type. Generally, small-diameter DN15~DN40 household meters use rotor type. Large-diameter process tables DN50~DN300 use screw type.

The main feature of the mechanical watch is that the initial investment is relatively low. However, the flow sensor has strict requirements on the bearing. In order to prevent long-term operation from causing large errors due to wear and tear, there are certain requirements for water quality. To prevent the rotating parts of the flowmeter from being blocked and affecting the instrument of normal work.

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.

According to the reflection principle of the ultrasonic heat meter, it is divided into a direct type ultrasonic heat meter and a reflective ultrasonic heat meter.

Among them, the direct type ultrasonic heat meter is suitable for large-diameter heat meters. The reflection type ultrasonic heat meter is suitable for small-diameter heat meters.

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.

BTU Meter for Chilled Water

In an era of ever-increasing energy costs. It is important to accurately measure and control energy consumption. Meet customer requirements by offering a wide range of highly advanced cooling metering instruments.

Chilled water energy meters, commonly referred to as BTU meters. Can be defined by measurement of heat/chilled water energy consumption.

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 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 clip-on temperature sensors are available. Installation is simple. low cost.

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

Problems and Solutions in the Use of Heat Meters

  1. The problem of blockage is the fatal problem of the heat meter.

There are two main sources of impurities in water: one is the rust produced by the oxidation and corrosion of the heating system, and the other is the residual debris after the construction of the heating system.

The main solution is to install a filter before the household heat meter. When a mechanical heat meter is used as a building heat meter. There should be two levels of filtration before the entrance. The aperture of the primary filter should be 3mm. The secondary aperture should be 0.65~0.75mm.

If a mechanical heat meter is used indoors as a tool for household heat (fee) apportionment, a filter with a filter diameter of 0.65~0.75mm should be installed before the household heat meter.

  1. Whether it is a building meter or a household meter, the heat meter has a specific flow accuracy performance curve. When selecting a heat meter, the system flow should be calculated. Make the correct selection according to the flow performance requirements of the heat meter, and do not directly select the heat meter according to the caliber. When designing, the specifications of the heat meter are generally determined according to the nominal flow rate equal to 80% of the design flow rate. And analyze the minimum possible flow of the system. Make the minimum flow value greater than the boundary flow value of the heat meter.
  2. There are many points worth noting during the installation and use of the mechanical heat meter. For example, rotary-wing heat meters should be installed horizontally. The upstream of the mechanical heat meter should maintain a straight pipe section with a length of 5D~10D. Downstream should maintain a straight pipe length of 2D~8D. At present, the installation of ultrasonic heat meters does not require straight pipe sections to ensure measurement accuracy.
  3. The installation position of the flow sensor of the heat meter should meet the installation requirements of the meter. It should be installed on the return pipe. This will help reduce the ambient temperature where the instrument is located. Extend battery life and improve meter usage.

At one point it was suggested that heat meters installed on the water supply would prevent users from stealing water. In fact, only the water meter can not measure the amount of stolen water. You can’t recover much lost water. It also makes the working environment of the heat meter worse.

Related Products


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.

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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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