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Metrys The Metrys wordmark, set in a high-contrast swash serif.
A Metrys BTU energy meter set: a blue flanged electromagnetic flow sensor with a coiled black cable, a beige wall-mounted calculator with an LCD and four keys, and a pair of temperature sensors with metal heads.
BTU energy meter, drawn illustration

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A Metrys BTU energy meter set: a blue flanged electromagnetic flow sensor with a coiled black cable, a beige wall-mounted calculator with an LCD and four keys, and a pair of temperature sensors with metal heads.
BTU energy meter, drawn illustration

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Flow meters BTU-1

BTU Energy Meter

An energy meter for chilled and hot water, reading heat and cooling.

Pipe size range
DN15 to DN6000
Accuracy
±0.5%
Outputs
4–20 mA, pulse and relay
Communication
RS485, HART or GSM/GPRS

Documents

Download datasheet (Opens in a new tab)

Overview

Why buyers choose it

  • Bills what was carried

    Flow times temperature difference — the figure a tenant on central chilled water actually owes.

  • Heat and cooling in one

    A building that changes over in March and October does not need two instruments.

  • Takes any flow input

    Ultrasonic on a retrofit riser, electromagnetic on new work. The energy calculation is unchanged.

  • A matched pair of sensors

    On chilled water the difference is a few degrees; two sensors disagreeing by half of one is an indefensible bill.

In detail

A BTU meter does not measure water, it measures what the water carried. Flow from a meter, temperature from a matched pair of platinum sensors in the flow and return, and the energy is the difference between them multiplied by what went past. That is what a tenant in a building on central chilled water is actually billed for.

It reads heat and cooling in the same instrument, which matters in a building that changes over in March and October and would otherwise need two. Chilled water, hot water and condenser water are all in scope.

The flow input is deliberately open: ultrasonic, electromagnetic or turbine, whichever suits the pipe. On a retrofit that usually means a clamp-on ultrasonic, because the riser cannot be cut; on new work an electromagnetic meter in the line is cheaper and more accurate. The energy calculation is the same either way.

Temperature comes from Pt100 or Pt1000 sensors — supplied as a matched pair, because on a chilled water circuit the difference being measured is a few degrees and two sensors that disagree by half of one produce a bill nobody can defend.

Technical specifications

Metrological

Measuring principle Thermal energy, flow with paired temperature sensors
Accuracy ±0.5%
Repeatability ±0.2% of span
Velocity range 0.3 to 10 m/s

Hydraulic

Measured media Chilled water, hot water and condenser water systems
Medium temperature Below 180 °C
Maximum working pressure 10, 16, 25 or 40 kg/cm²

Materials

Enclosure material Aluminium, ABS plastic or mild steel

Electrical

Power supply 230 V AC, 24 V DC or battery
Outputs 4–20 mA, pulse and relay
Display LCD showing flow rate, totaliser, heat flow rate and heat totaliser

Communication

Communication RS485, HART or GSM/GPRS

Environmental

Protection class IP65 compact; IP67 or IP68 remote
Ambient conditions −20 to +60 °C, 5% to 90% humidity

Dimensions and installation

Schematic, not to scale
Pipe size range DN15 to DN6000
End connection Flanged, wafer, tri-clover, clamp-on or insertion
Transmitter mounting Integral or remote; portable or wall-mounted

Parts

Parts of a heat meter

How a meter of this type is built, and what this model is made of.

Parts of a heat meter, drawn illustration Exploded illustration of a BTU energy meter's parts, numbered top to bottom above the supply and return pipes: 1 calculator with display, 2 flow sensor, 3 supply temperature sensor, 4 return temperature sensor, 5 sensor cable, 6 thermowell, 7 mounting clamp. 1 2 3 4 5 6 7
Illustrative: how a meter of this type is built. This model's own materials and figures are in the table and its specifications.

  1. Calculator with display

    Combines the flow and temperature signals into an energy reading.

    Display LCD showing flow rate, totaliser, heat flow rate and heat totaliser

  2. Flow sensor

    Measures the volume of water circulating through the circuit.

  3. Supply temperature sensor

    Measures the water temperature leaving the heat source.

  4. Return temperature sensor

    Measures the water temperature returning to the heat source.

  5. Sensor cable

    Carries the temperature signals to the calculator.

  6. Thermowell

    Protects each temperature sensor from direct contact with the flow.

  7. Mounting clamp

    Secures the calculator to the pipe or wall.

Download centre

Everything you need to specify.

Documents for the BTU Energy Meter.

Approvals and certificates

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