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Energy Meter BTU Meter DN-EM

Energy Monitoring of Heating or Cooling Systems, 1/4", 3/8", 1/2” & 3/4” Pipe

DESCRIPTION

The DN-EM Energy Meter / BTU Meter is an economical energy flow meter intended for applications in energy transfer and heating/ cooling systems where energy use requires measurement.

In heat exchange loops the DN-EM internally calculates the energy gained or lost by the heat exchanger. The energy is calculated based on the the mass volume rate and the difference in temperature between the supply and return lines. The volume of liquid is measured by means of a pulse generating vortex flow meter. A RTD sensor built into the flow meter (T1) measures temperature at the meter and the remote temperature (T2) is measured by means of a precision RTD sensor mounted in a pipe tee.

A scaled pulse output is provided and can be configured to report volume flow rate, mass flow rate or energy total. Modbus 485 communications provides an interface with a building automation or monitoring system.

The unit contains non-volatile memory that records, mass flow and energy, and is updated every ten minutes. However, when flow, mass or energy totals are read, the reported values are true current values; the last stored value is added to the current accumulated value when the applicable register is read.

The default medium for the DN-EM is water. Other media consisting of water and a certain percentage of glycol up to 60% can be field configured.

FEATURES

  • COMPENSATED TEMPERATURE MEASUREMENT
  • ACCURATE FLOW MEASUREMENT
  • COMPENSATED FOR SPECIFIC HEAT OF A RANGE OF GLYCOLS

Table 1 — Models

Model Pipe Size Full Scale Range (Gal/min) Full Scale Range (l/min) Flow Pulse Output Configuration (Pulses/Gallon) Flow Formula (Q=Flow in GPM) Max. Pressure Drop (PSI)
DN-EM8 1/4" 0.25 to 4.00 0.9 to 15.0 7200 Q= 0.00833xFreq. 2.9
DN-EM10 3/8" 0.50 to 8.00 1.8 to 32.0 3600 Q= 0.01667xFreq.
DN-EM15 1/2” 0.90 to 13.20 3.5 to 50.0 2000 Q= 0.06xFreq.
DN-EM20 3/4” 1.30 to 22.50 5.0 to 85.0 1200 Q= 0.1xFreq.

SPECIFICATIONS

Medium: Suitable for water & water glycol based heat exchange systems and other liquids compatible with 
the materials of construction (consult factory). For media with viscosity greater than 2 millipascal seconds 
(2 centipoise), higher flow rates are required to form vortices raising the minimum measurable flow rate value.
Flow ranges: From 0.25 to 22.5 GPM, See Table 1
Temperature measurement: 3-wire,1000 Ohm RTD
	1 RTD imbedded in flow sensor
	1 RTD packaged in a 1/4" x 2.5" stainless steel sheath with 1/2" NPT brass adjustable compression fitting for 
	mounting in a 1/2" or 3/4" pipe Tee; supplied connected to energy monitor with 10 ft of 3-wire RTD cable. 
	Pipe Tee is an ordering option, see Table 11.
Temperature:
	Ambient: 5° to 185°F (–15° to +85°C)
	In storage: -22° to 185°F (-30° to +85°C)
Max. pressures and liquid temperature:  See table 2

Table 2 — Maximum Operating Pressure & Temperature

PSI Bar °F °C Duration
174 12 104 40 Lifetime
100 6.89 200 93.3 Lifetime
87 6 212 100 Lifetime
58 4 257 125 600 hours
58 4 284 140 2 hours 

Max. test pressure: 261 psi/18 bar at 104°F/40°C
Loss of pressure / cavitation: A minimum inlet pressure of 10.2 psi (0.7 bars) is required to avoid cavitation 
issues at maximum flow.
Wetted materials:
Flow sensor and bluff:
	ASTM- PPA, Polyphthalamide
	 ISO-PA6T/6I, Grivory 40%GF
	 Sensor vane: ETFE
	 Sealing material: EPDM
Flow Accuracy:
	Up to 50% fs: ≤ 1% fs
	From 50% fs: ≤ 2% of measured value
Temperature measurement accuracy: Reported supply & return temperatures are per PT1000, 
DIN EN 60751 Class B. Temperature difference used in energy calculation is product of 
matched pair RTD’s calibrated at factory to report temperature difference to ±(0.1 + 0.002*T) Degs C.
Operating Differential Temperature Range: 3°C to 91°C (5.4 to 164°F), consult factory for other.
System accuracy: EN1434-1, Class 2 & 3 (see Table 3)
Protection class: NEMA 4X (IP65)
Mounting position: Flow direction is identified by an arrow on flowmeter body. Otherwise the flowmeter 
mounting orientation is universal.
Units of Measurement:  Factory set or Field programmable
	Flow Rate: Gals/Min, Liters/Min
	Mass Flow: Lbs/Min, Kgs/Min
	Energy Rate: BTU/Min, kBTU/Min, kBTU/Hr, KW
	Total Flow: Gals, Liters, Cubic Meters
	Total Energy: kBTU, KW-HRS
	Temperature: °F, °C
Output Update Rate: 2 seconds
Power: 12 to 30 VDC
Current Consumption: < 10 mA
Pulse Output: Can be factory set or field configured to report volume flow rate, mass flow rate or energy total. 
Output is either an optically isolated NPN transistor with maximum sinking capability to 50 mA from a voltage 
source of no more than 48 VDC or a voltage output (power supply voltage). Pulse duration is 2 ms when reporting 
flow rate and 10 ms when reporting energy total (consult factory for different pulse duration)
Security: Holographic tamper evident label seal with unique serial number provided for electrical enclosure cover. 
Optional hour meter mounted in enclosure cover available to monitor power.
Energy Measurement:
	T1 RTD is located in the flow sensor
	T2 Remote RTD is installed in a pipe tee
Heating and cooling energy are both measured and totaled in separate registers in model DN-EM. The values can 
be interrogated via the Modbus Master.
	1) Heating Mode: T1>T2
	2) Cooling Mode: T2>T1
Depending on factory or field setup, the energy total pulse output functions in the absolute mode, indifferent as 
to whether in the heating-or-cooling mode,heating-only mode or cooling-only mode.
Modbus Operability:
	Baud Rate: 9600 (default) or 19.2 KB/S
	Parity: Selectable, None (default), Even, Odd
	Slave Id: 01-255 (default is 01)
	Function Codes: 03, 05 & 06 are supported
	Exception Codes: 01, 02 & 03 are supported
	Data types: Word, Double
	Data is sent "Big Endian", i.e. most significant byte first
Flow and energy data updated every 2 seconds.
Turn around time is less than 2 seconds. Since the data is updated every 2 seconds, reading data at intervals 
greater than the update time will ensure that current values will always be fresh. 
Commissioning: The DN-EM requires no special software to set the desired communication parameters. 
It can be done at the factory or from the User's Modbus Master over the RS-485 network. Stand alone 
commissioning can be done via PC serial port (model 43-119, RS-485 converter required). 
A 600 Ohm bus termination resistor can be jumper selected on the pcb. Download commissioning software HERE.
Wiring Connection:
	10 ft shielded 3-conductor plenum cable for RS-485
	10 ft shielded 4-conductor plenum cable for power & pulse output.
	Liquidtight 1/2" non-metallic conduit connector supplied for cable entry to enclosure
Pipe Connections: 304 Stainless Steel threaded adapters or brass solder adapters, see tables 7 & 8.

Table 3 - Maximum Error or Energy Measurement

Flow Percent F.S. 10 20 30 40 50 60 70 80 90 100
Delta T ¼C Delta T ¼F
3.0 5.4 14.4% 9.6%    
3.9 7.0 13.4% 8.5%
5.1 9.1 12.5% 7.7%
6.6 11.9 11.9% 7.0%  
8.6 15.4 11.4% 6.5%
11.1 20.0 11.0% 6.1%
14.5 26.1 10.7% 5.9%
18.8 33.9 10.5% 5.6%
24.5 44.0 10.3% 5.5%
31.8 57.3 10.2% 5.3%
41.4 74.4 10.1% 5.2%
53.8 96.8 10.0% 5.1%
69.9 125.8 10.0% 5.1%
90.9 163.6 9.9% 5.0%
  Class 2 & 3   Class 2   

About EN 1434-1 Max. Permissable Errors of Complete Heat Meters

Class 2: E = ± (3+4"ΔΘ min. / ΔΘ + 0.02 qp/q
Class 3: E = ± (3+4"ΔΘ min. / ΔΘ + 0.05 qp/q

Where:
    E= Max. permissible error (%) 
    ΔΘ min.= Lower limit of temperature difference (3°C)   
    ΔΘ = Temperature difference between supply & return of the heat exchange circuit
    qp = Highest flow-rate at which energy meter shall function continuously without maximum 
	   permissable errors being exceeded (stated full scale value of DNEM)
    q = Flow rate

Note: Accuracy statements apply to meters with matched temperature probes provided as original 
equipment from factory.

Table 4 — Read Data Registers

Variable Register Number # Registers Function Code Data Type Description
FLOW RATE 40001 2 03 Double Returns flow rate in selected units
ENERGY RATE 40003 2 03 Double Returns energy rate in selected units
MASS RATE 40005 2 03 Double Returns mass flow rate in selected units
FLOW TOTAL 40007 2 03 Double Returns total flow in selected units since last reset
HEATING TOTAL 40009 2 03 Double Returns total heat energy in selected units since last reset
COOLING TOTAL 40011 2 03 Double Returns total cooling energy in selected units since last reset
MASS TOTAL 40013 2 03 Double Returns total mass in selected units since last reset
LOCAL TEMP 40015 2 03 Double Returns local temperature in selected units
REMOTE TEMP 40017 2 03 Double Returns remote temperature in selected units

Table 5 — Setup Functions, Write Data Registers

Variable Register Number # Registers Function Code Data Type Description
SET FLOW RATE UNITS 40101 1 06 Word Units of flow rate; 0=G/M, 1=L/M
SET ENERGY RATE UNITS 40102 1 06 Word Units of energy rate; 3=BTU/M, 4=KBTU/M, 5=KBTU/HR, 6=KW
SET MASS FLOW RATE UNITS 40103 1 06 Word Units of mass rate; 7=LBS/MIN, 8=KG/MIN
SET FLOW TOTAL UNITS 40104 1 06 Word Flow total units; 9=GALS, 10=LITERS, 11=CUBIC METERS
SET ENERGY TOTAL UNITS 40105 1 06 Word Energy total units; 12=kBTU, 13=W-HRS, 14=KW-HRS
SET MASS TOTAL UNITS 40106 1 06 Word Mass units; 15=LBS, 16=KG
SELECT PULSE OUTPUT 40107 1 06 Word Select Energy, Flow or Mass as pulse output; 0=FLOW, 1=ENERGY, 2=MASS
SELECT TEMPERATURE UNITS 40108 1 06 Word Select Deg F or Deg C; 0=DEG F, 1=DEG C
SELECT MEDIA TYPE 40109 1 06 Word 0=WATER, 1,(2)=ETHYLENE GLYCOL 92% (95.5%), 2(3) = PROPYLENE GLYCOL 94% (96%)
SET % GLYCOL 40110 1 06 Word Enter percent added; 10 to 60
SET PULSE TYPE 40111 1 06 Word 0 = UNIVERSAL; 2 = HEATING ONLY; 3 = COOLING ONLY
SET MIN. HEATING DELTA T 40112 1 06 Word 2 DEG F TO 5 DEG F
SET MIN. COOLING DELTA T 40113 1 06 Word 2 DEG F TO 5 DEG F

Table 6 — Commissioning & Other Functions, Write Data Registers

Variable Register Number # Registers Function Code Data Type Description
* SET SLAVE ID 40201 1 06 Word 01 is factory set 0 to 255
* BAUD RATE 40202 1 06 Word 19.2 KB 0R 9600 (DEFAULT) 0=9600, 1=19.2kb
* SET PARITY 40203 1 06 Word None, odd, even (default) 0,1,2
RESET FLOW TOTAL 00001 1 05 Word Clears totalized flow
RESET HEATING ENERGY TOTAL 00002 1 05 Word Clears totalized heating energy
RESET COOLING ENERGY TOTAL 00003 1 05 Word Clears totalized cooling energy
RESET MASS TOTAL 00004 1 05 Word Clears totalized mass
SET DEFAULT UNITS 00005 1 05 Word Resets all units to factory defaults
*Can only be set when commissioning 

Commissioning from a personal computer is straightforward with Clark commissioning software. 
Download HERE
Clark commissioning software.

Table 7 - Dimensions

Model A B C
DNEM8 2.83 (72) 1.14 (28.9) 1.30 (32.9)
DNEM10 3.03 (77) 1.14 (28.9) 1.30 (32.9)
DNEM15 3.23 (82) 1.30 (33) 1.54 (39)
DNEM20 4.13 (105) 1.47 (37.4) 1.54 (39)
Dimensions do not include pipe fittings. See tables 9 & 10 for standard fitting offerings.

DIMENSIONS (INCHES)

Dimensions

Table 8 - Flow Constants When Pulse Output Is Programmed To Report Flow
Flow Constants
Unit 1/2” Monitor 3/4” Monitor
Pulse/Unit Flow Rate Pulse/Unit Flow Rate
GAL/MIN 1000 P/G GAL/MIN= .06xFREQ 600 P/G GAL/MIN= .1xFREQ
LITER/MIN 300 P/L LITER/MIN= .2xFREQ 150 P/L LITER/MIN= .4xFREQ
LITER/SEC 15,000 P/L LITER/SEC= .004xFREQ 10,000 P/L LITER/SEC= .006xFREQ
LB/MIN 120 P/LB LB/MIN= .5xFREQ 80 P/LB LB/MIN= .75xFREQ
KG/MIN 80 P/KG KG/MIN= .75xFREQ 150 P/KG KG/MIN= .4xFREQ

Pipe adapters

Table 9 — Stainless Threaded adapters (1/2"& 3/4" NPT)

Fitting Kit P/N
(Includes 2 clips, 2 O-rings, 2 adapters)		 Clip Part Number O-Ring Part Number
(Material)		 Threaded adapter Part Number Material A B C D E F G H
Inch mm Inch mm Inch mm Inch mm Inch mm Inch mm Inch mm
KADS1/4 C810 R810E (EPDM) ADS1/4 304 SS 1/4” NPT 1.76 44.65 2.27 57.65  0.551 14  1.142 29 0.965 24.5 0.236 6 1.21 30.8
KADS3/8 C810 R810E (EPDM) ADS3/8 304 SS 3/8” NPT 1.76 44.65 2.27 57.65 0.551 14 1.142 29 0.965 24.5 0.236 6 1.21 30.8
KADS1/2 C15 R15E (EPDM) ADS1/2 303SS 1/2" NPT 1.97 50.05 2.64 67.05 0.646 16.4 1.260 32 1.1 28 0.191 4.85 1.36 34.5
KADS3/4 C20 R20E (EPDM) ADS3/4 303SS 3/4" NPT 2.32 58.85 3.36 85.25 0.731 18.6 1.499 37.8 1.1 28 0.315 8 1.36 34.5
The DN-EM offers great flexibility with respect to piping connections. Inserting and removing fittings is easy.
A clip secures the end fitting to the flow sensor and an o-ring provides the seal.

Brass Solder adapters

Table 10 — Brass Solder adapters

Fitting Kit P/N
(Includes 2 clips, 2 O-rings, 2 adapters)		 Clip Part Number O-Ring Part Number
 adapter Part Number Material Standard Tubing Size
(For Use with Type K & Type L Copper)
KSADB1/4 C810 R810E SAD1/4 360 Brass 1/4”
KSADB3/8 C810 R810E SAD3/8 360 Brass 3/8”
KSADB1/2 C15 R15E (EPDM) SADB1/2 360 Brass 1/2"
KSADB3/4 C20 R20E (EPDM) SADB3/4 360 Brass 3/4"

ELECTRICAL

RS-485: 3-conductor cable
	Red: TXD1
	Black: TXDO
	Green or Clear: GND
Power & NPN Transistor Out: 
	 4-conductor cable
	 Red (+): Vin 12 to 30 VDC
	 Black (-): Vin Return
	 Green : OPTO NPN E
	 White: OPTO NPN C
Optional Model 43-119, RS-485 Converter for Commissioning from a PC 
Optional Model 43-119, 
RS-485 Converter for Commissioning 
from a PC:
PC End: DB9 Female
RS-485 End: Terminal Block
Terminal Block Connections to DN-EM:
	Black: TD(A)-
	Red: TD(B)+
	Clear or Green: Gnd
 Pulse output wiring
Note: NPN Opto-isolated switch output (Order code I) and
Vo Powered Pulse Output (order code V) are jumper selected
at the factory.

ORDERING INFORMATION

Order Number Examples: DNEM20KSADB3/4V1 DNEM8KADS1/4I2

Model DN-EM is supplied programmed with a configuration determined by the customer and expressed 
in the order nomenclature below. The setup can be changed in the field (see DN-EM installation manual) 
using Modbus Master over the RS485 network or via Clark Sonic commissioning software installed on a PC 
(RS 485 converter needed, such as Clark model 43-119). If you require the factory to provide a non-default 
configuration (Default Configuration #3), please DOWNLOAD a Factory Configuration Sheet.

Table 11

Model End Fittings (Tables 9 & 10)* Pulse Out Config. Factory Default Configuration
1= Default Config. #1 2= Default Config. #2 3= Default Config. #3
DNEM8 KADS1/4 I=Opto-Isolated NPN Pulse Output: 1 pulse = 1000 Btu (1 KBtu) Pulse Output: 1 pulse = 1 KW-Hr User Specified - user must download, fill out and submit the
Factory Configuration Sheet.
DNEM10 KADS3/8 V= Voltage Pulse Pulse Type: Universal Pulse Type: Universal
DNEM15 KADS1/2 Media: Water, no glycol Media: Water, no glycol
DNEM20 KADS3/4 Volume Flow Rate Units: Gallons/Min Volume Flow Rate Units: Liters/Min
KSADB1/4 Mass Flow Rate Units: Lbs/Min Mass Flow Rate Units: KG/Min
KSADB3/8 Volume Total Units: Gallons Volume Total Units: Liters
KSADB1/2 Mass Total Units: Lbs Mass Total Units: KG
KSADB3/4 Energy Rate Units: kBtu/Min Energy Rate Units: KW
Energy Total Units: kBtu Energy Total Units: KW-Hrs
Temperature Units: oF Temperature Units: oC
Baud Rate: 9600 Baud Rate: 9600
Parity: None Parity: None
Slave ID: 01 Slave ID: 01
 
Options
H= Hour Meter installed in enclosure cover to monitor power supply
*Note: last 2 digits define flowmeter size (KADS3/8 is for use with DNEM10, 3/8” pipe size)

Model  Description
43-119 PC Serial Port to RS-485 converter
43-122 Solder Joint Brass Pipe Tee, 1/2 “ Pipe x 1/2” NPT Branch
43-123 Solder Joint Brass Pipe Tee, 3/4 “ Pipe x 1/2” NPT Branch
43-125 Solder Joint Brass Union, 1/2 “
43-126 Solder Joint Brass Union, 3/4 “
43-152 Serialized Hologram Security Label, 0.5” x 0.6”
ADS1/4 1/4” NPT SS Adapter
ADS3/8 3/8” NPT SS Adapter
ADS1/2
1/2” NPT SS Adapter
ADS3/4 3/4” NPT SS Adapter
SADB1/4 1/4” Brass Solder Adapter
SADB3/8 3/8” Brass Solder Adapter
SADB1/2 1/2” Brass Solder Adapter
SADB3/4 3/4” Brass Solder Adapter
C810 Clip
C15 Clip
C20 Clip
R810E EPDM O-ring
R15E EPDM O-ring
R20E EPDM O-ring
DN-EM BTU/Energy Monitor

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