Measure Flow
A Cadillac® flow meter measures the volume of water moving through the heating or cooling circuit and sends its flow signal to the HEATX.
HEATX BTU Energy Meter
Combined with precision matched 4-wire RTD assemblies, and the HEATX BTU / Energy computer Cadillac® Meters offer the most accurate BTU/Energy measurement system currently available for measurement and billing purposes.
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The Cadillac® BTU Meter (HEATX) is designed to measure the energy consumed in hot water heating and chilled water cooling systems. The system is a rate and totalizing device, which is capable of calculating and displaying Volume, Energy, Temperatures and Peak Energy usage. Combined with Cadillac®’s superior flow meter technologies the HEATX provides the most accurate, repeatable, and maintenance free energy system available in the industry.
The Cadillac® BTU Meter (HEATX) measures the temperature in the feed and return lines via two precision matched 4-wire RTD’s and from this calculates the density and enthalpy of the water. In addition, by also measuring the volume of water flowing in the system via the Cadillac® flow meter, the HEATX will then compute, display, and output the Energy consumed.
The New Industry Standard
Combined with Cadillac®’s superior flow meter technologies the HEATX BTU meter has quickly become acknowledged as the industry standard. Customers choose the Cadillac® HEATX BTU Meter because of proven: accuracy, dependability, consistency, maintenance, reliability and rangeability.
Cadillac® BTU / Energy Meter has the ability to provide the best suited and widest range of application solutions to meet the end users energy measurement needs.
Technical Product Guide
Cadillac® HEATX BTU Energy Meter
Explore the HEATX system’s applications, operating principle, measurement modes, specifications, installation requirements and model-selection information for hot-water heating and chilled-water cooling systems.
Product Overview
Thermal Energy Measurement for Heating and Cooling Systems
The Cadillac® HEATX BTU Energy Meter is designed to measure thermal energy consumed in hot-water heating and chilled-water cooling systems. It operates as both a rate-measuring and totalizing device, giving system operators a clear view of current and accumulated energy use.
The HEATX combines flow data from a Cadillac® flow meter with temperature measurements from two precision-matched, four-wire RTD assemblies. Using these measurements, it calculates the density and enthalpy of the water and determines the energy transferred through the system.
Measured and Calculated Values
The HEATX can calculate and display volume, thermal energy, feed and return temperatures, temperature differential and peak energy usage.
Operating Principle
How the HEATX Calculates Thermal Energy
The HEATX determines the amount of thermal energy transferred by combining the measured water flow with the temperature difference between the system’s supply and return lines. The instrument processes these inputs continuously to provide both current energy rate and accumulated energy totals.
Compare Temperatures
Two precision-matched, four-wire RTD assemblies measure the water temperatures in the supply and return lines.
Calculate Energy
The HEATX uses the measured flow and temperatures to calculate water density, enthalpy and the thermal energy transferred through the system.
Display and Totalize
Calculated values are displayed locally, while energy usage is totalized to support monitoring, control, reporting and billing.
Heating and Cooling Operation
In a heating system, energy is released as the water cools between the supply and return measurement points. In a chilled-water system, energy transfer is determined as the water absorbs heat and its temperature rises.
Continuous System Insight
The combination of instantaneous readings and accumulated totals
allows operators to assess both present system demand and energy
consumption over time.
Operating Modes
Configurable Energy Measurement Modes
The HEATX can be configured for four operating modes to match the direction and type of thermal-energy transfer within the application. Each mode determines how positive and negative temperature differences are handled by the meter’s energy registers.
Heating Mode
Only positive temperature differentials are totalized. This mode is intended for systems in which energy is delivered through hot-water heating.
Cooling Mode
Only negative temperature differentials are totalized. This mode is intended for chilled-water cooling applications.
Heating/Cooling Mode
The energy total increases whether the temperature differential is positive or negative. This supports systems in which energy flow may alternate between heating and cooling.
Charge/Discharge Mode
Two separate registers independently totalize positive and negative energy values, allowing charging and discharging activity to be recorded separately.
Local Display Measurements
Energy Total
Energy Flow Rate
Volumetric Flow Rate
Volume Total
Feed Temperature
Return Temperature
Temperature Differential
Peak Energy Usage
Measurement System
Sensors, Flow Measurement and System Outputs
A complete HEATX measurement system combines the energy computer, a precision-matched pair of temperature sensors and a compatible Cadillac® flow meter. The accuracy and configuration of each component must be considered when specifying the complete installation.
HEATX Energy Computer
- Calculates, displays and totalizes thermal-energy measurements
- Front-panel configuration without a separate computer
- Field adjustment for differential-temperature offset
Temperature Sensors
- Precision-matched, four-wire PT100 RTD assemblies
- Bath calibrated with NIST-traceable calibration
- Thermowell and junction-style head with field-wiring terminations
Recommended CMAG Flow Meter
- No moving parts or obstruction in the flow path
- Suitable for installation in any orientation
- Integral or remote electronics with a two-line backlit LCD
| Measurement Element | Published Performance | Technical Detail |
|---|---|---|
| Temperature Sensors | ±0.01% of temperature span | Precision-matched, bath-calibrated PT100 RTDs |
| Differential Temperature | ±0.10°F or better | Includes meter adjustment capability |
| CMAG Flow Measurement | ±0.50% of rate generally | ±0.25% of rate with 1.5 pipe diameters upstream and downstream from the meter centreline |
| CMAG Turndown | Minimum 300:1 | At the stated ±0.25% of rate accuracy |
Communications and Outputs
Depending on the selected model code, HEATX output options may include:
RS-485 Modbus RTU
Modbus TCP/IP
BACnet TP
N2
Open-Collector Pulse
Installation
HEATX System Layout and Installation Planning
A complete HEATX installation uses a flow meter to measure the volume passing through the circuit and two matched RTD assemblies to measure the feed and return temperatures. These field measurements are transmitted to the HEATX energy computer, which calculates, displays and totalizes the transferred thermal energy.
Position the Flow Meter
Install the selected Cadillac® flow meter in the measured water circuit according to its product-specific installation instructions and required straight-pipe conditions.
Install the RTDs
Place the matched four-wire RTD assemblies at the designated feed and return measurement points so the HEATX can determine the system’s temperature differential.
Connect the Inputs
Route the flow and temperature signals to the HEATX energy computer in accordance with the wiring information supplied for the ordered meter configuration.
Configure and Verify
Confirm the operating mode, engineering units, input configuration and required outputs before placing the complete measurement system into service.
Thermal-Energy Calculation
P = V × ρ × (htv − htr)
- P = Power in watts
- V = Volumetric flow rate
- ρ = Water density
- htv = Specific enthalpy at feed temperature
- htr = Specific enthalpy at return temperature
Important Installation Note
Final positioning, wiring and commissioning must follow the documentation supplied with the exact HEATX and flow-meter model ordered. Available connections and outputs vary by configuration.
Product Selection
Information Required to Specify a HEATX System
The HEATX energy computer, matched temperature sensors, flow meter, power requirements and communication outputs must be selected as one coordinated measurement system. Providing complete application data allows Cadillac Meter to identify the appropriate configuration and prepare an accurate quotation.
Define the Application
- Heating, cooling, combined heating/cooling or charge/discharge
- Closed-loop or applicable process-water system
- Required energy and flow engineering units
Provide Operating Data
- Minimum, normal and maximum flow rates
- Feed and return temperature ranges
- Expected differential temperature
- Pipe size, material and available installation space
Select System Components
- Compatible Cadillac® flow-meter type and size
- Matched PT100 RTD assemblies
- Appropriate sensor insertion and thermowell arrangement
- Integral or remote equipment locations
Confirm Electrical Needs
- Available power supply
- Required communication protocol
- Pulse or network output requirements
- Building-management or control-system compatibility
Before Requesting a Quote
Gather the design flow, operating temperatures, pipe information, preferred flow-meter arrangement, available power and required communications. If replacing an existing instrument, include its model number and clear photographs of the current installation.
Frequently Asked Questions
Common HEATX Energy Meter Questions
What does the HEATX measure?
The HEATX calculates thermal-energy transfer using the measured volumetric flow rate and the temperature difference between the feed and return sides of the water circuit. It can display and totalize energy, flow, volume and temperature measurements.
Can it measure heating and cooling?
Yes. The available operating modes support heating, cooling, combined heating and cooling, and systems where charging and discharging energy must be recorded in separate registers.
Which temperature sensors are used?
The system uses a precision-matched pair of four-wire PT100 RTD assemblies. The sensors are bath calibrated and supplied with NIST-traceable calibration for accurate differential-temperature measurement.
Which flow meter is recommended?
A Cadillac® CMAG magnetic flow meter is commonly recommended because it has no moving parts or obstruction in the flow path. The correct meter type and size must still be selected for the application’s pipework and operating range.
Can the HEATX connect to a control system?
Depending on the ordered configuration, communication options may include Modbus RTU, Modbus TCP/IP, BACnet TP, N2 and an open-collector pulse output. Required communications should be confirmed before ordering.
Can the meter be configured in the field?
The HEATX is factory configured for the specified application, but settings can be accessed through the front-panel keypad without a separate computer. Field adjustment is also available for compensating for a differential-temperature offset.
Technical Documentation
Download the HEATX Technical Product Guide
View or download the complete HEATX technical guide for convenient reference when reviewing applications, system components, specifications, installation requirements and product-selection information.
HEATX Technical Guide
Opens the complete PDF guide in Google Drive, where it can be viewed, printed or downloaded.
View or Download the PDF Review Selection Requirements