Danfoss Heat Cost Allocator Operating guide

Operating Guide

Electronic Heat Cost Allocator

Table of Contents	1.	General......................................................................................................................................		3
	1.1	Application..........................................................................................................................................................		3
	1.2	General Guidelines...........................................................................................................................................		3
		1.2.1	Hazards and Disposal...............................................................................................................................	3
		1.2.2	Changing the Battery...............................................................................................................................	3
		1.2.3	Installation with Glue...............................................................................................................................	3
		1.2.4	Warranty.......................................................................................................................................................	3
		1.2.5	Compliant Use............................................................................................................................................	3
		1.2.6	Non-compliant Use...................................................................................................................................	3
		1.2.7	Notes regarding Installation..................................................................................................................	3
		1.2.8	Protection against Outside Influences..............................................................................................	3
		1.2.9	Data Collection while the Device is open.........................................................................................	4
		1.2.10	Transport in Original Packaging..........................................................................................................	4
		1.2.11	New Programming....................................................................................................................................	4
	1.3	Restrictions.........................................................................................................................................................		4
		1.3.1	Applications.................................................................................................................................................	4
		1.3.2	Measurement using Single or Dual Sensors....................................................................................	4
		1.3.3	Exclusion of Liability.................................................................................................................................	4
		1.3.4	Modifications..............................................................................................................................................	4
	2.	Product Description................................................................................................................		4
	2.1	Packaging............................................................................................................................................................		4
	2.2	General Description.........................................................................................................................................		4
		2.2.1	Type................................................................................................................................................................	4
		2.2.2	Design............................................................................................................................................................	4
		2.2.3	Characteristics............................................................................................................................................	5
		2.2.4	Display...........................................................................................................................................................	5
		2.2.5	Electronics....................................................................................................................................................	5
		2.2.6	Versions.........................................................................................................................................................	5
		2.2.7	Optical Interface........................................................................................................................................	6
		2.2.8	Radio Wireless M-Bus...............................................................................................................................	6
	2.3	Technical data.....................................................................................................................................................		6
	3.	Settings.....................................................................................................................................		7
	3.1	Settings................................................................................................................................................................		7
	3.2	Operating mode...............................................................................................................................................		9
		3.2.1	Cycle................................................................................................................................................................	9

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Table of Contents		3.2.2	Single Sensor Version with Start Sensor...........................................................................................	10
(continuous)		3.2.3	Dual Sensor Version..................................................................................................................................	10
		3.2.4	Comparison of the Measuring Principles.........................................................................................	10
		3.2.5	Temperature Measurement and Calculation..................................................................................	10
		3.2.6	Calculation of the Displayed Consumption Value.........................................................................	11
		3.2.7	Start of Counting.......................................................................................................................................	11
	3.3	Display and Additional Functions..............................................................................................................		12
		3.3.1	The Menu Sequences of the Digital Display...................................................................................	12
		3.3.2	The Digital Display....................................................................................................................................	12
		3.3.3	Rolling Display............................................................................................................................................	15
		3.3.4	Communication Indicator and Measuring Indicator •...........................................................	16
		3.3.5 Real Time Clock and Calendar..............................................................................................................		16
		3.3.6	Check code..................................................................................................................................................	16
	3.4	Special Functions..............................................................................................................................................		17
		3.4.1	Suppression of Summer Counting......................................................................................................	17
		3.4.2	Annual Reset of the Consumption Value..........................................................................................	17
		3.4.3	Unit Scale and Product Scale................................................................................................................	17
	3.5	Parameterization..............................................................................................................................................		17
	3.6	Error.......................................................................................................................................................................		17
		3.6.1	List of Errors.................................................................................................................................................	17
	4.	Installation...............................................................................................................................		18
	4.1	Introduction.......................................................................................................................................................		18
	4.2	DIN Standard Requirements for the Installation..................................................................................		18
	4.3	General Restrictions........................................................................................................................................		18
	4.4	Operating Range..............................................................................................................................................		18
	4.5	Allocator Installation Position – Standard Installation.......................................................................		19
	4.6	Mounting the Remote Sensor......................................................................................................................		20
	4.7	Wall Mounting...................................................................................................................................................		21
	4.8	Installation of Fastening Parts Kits.............................................................................................................		22
		4.8.1	Installation to Sectional Radiator, direct mounting......................................................................	22
		4.8.2	Sectional Radiator, wall mounting......................................................................................................	22
		4.8.3	Installation on Folded Radiator............................................................................................................	23
		4.8.4	Folded Radiator, wall mounting...........................................................................................................	23
		4.8.5	Installation to Panel Type Radiator.....................................................................................................	24
		4.8.6	Mounting of heat cost allocators with glue.....................................................................................	24
		4.8.7	Panel Type Radiator, wall mounting...................................................................................................	25
		4.8.8	Installation to Panel-Type Radiator with Front Convection Plate............................................	25
		4.8.9	Bathroom radiator – Towel rails...........................................................................................................	26
		4.8.10	Sectional Radiator wide..........................................................................................................................	27
	4.9	Overview mounting accessories.................................................................................................................		27
	4.10 Mounting and Sealing....................................................................................................................................			28
	5.	Commissioning........................................................................................................................		28
	5.1	Automatic commissioning during the installation..............................................................................		28
	5.2	Commissioning by pressing push button...............................................................................................		29
	5.3	Radio Standby....................................................................................................................................................		29
		5.3.1	Sleeping Mode...........................................................................................................................................	30
		5.3.2	Installation Mode.......................................................................................................................................	30
		5.3.3	Operation Mode.........................................................................................................................................	30
	6.	Readout.....................................................................................................................................		30
	6.1	Remote Radio Reading...................................................................................................................................		31
		6.1.1 General Information about the Remote Radio Readout.............................................................		31
		6.1.2 WireIess M-Bus Remote Radio Readout............................................................................................		31
		6.1.3 Readout using the Radio Central SonoCollect................................................................................		31
	7.	Rating factors...........................................................................................................................		32
	7.1	Taking Measurements.....................................................................................................................................		32
		7.1.1	Rating of Radiators with Over Length or High Nominal Power...............................................	32
		7.1.2	Rating of Radiator......................................................................................................................................	32
	7.2	Table of Rating Factors....................................................................................................................................		33
	7.3	Rating Factor according EN 834:2013........................................................................................................		33

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1.	General	This manual serves as a reference for users
1.1	Application	and service personnel of the Danfoss heat cost
		allocators. It describes the use of the SonoHCA
		heat cost allocators.

The heat cost allocator is a measuring device to record the heat output of radiators in units. Units are apartments, offices, and business,

commercial or industrial premises whose heat is supplied through a central heating system or via a conjoint district heating station.

The group of units constitutes one billing unit.

If one billing unit includes units with differences, for example, from a technical standpoint (in

the form of different heating systems) or in terms of consumption behaviour (i.e. in the case of industrial premises and apartments), a subdivision of the billing units into unit groups may be necessary.

Each radiator is fitted with a heat cost allocator which records and assesses the heat output of the radiator and displays the consumption value.

The consumption value is the basis for allocating the heating costs to each unit, which is necessary for the annual billing of the heating costs.

The heat cost allocators are principally used in the following units:

•Collective housing buildings.

•Offices or administrative buildings.

The typical users are:

•Measuring and billing services.

•Cooperatives or property managers.

•Building service companies, letting agencies.

The heat cost allocators can be installed on:

•Sectional radiators.

•Column/tube radiators.

•Panel radiators with horizontal or vertical water flow.

•Flat register radiators.

•Convector heaters.

1.2 General Guidelines	1.2.1 Hazards and Disposal
	The heat cost allocators are equipped with
	lithium batteries. This type of battery falls into
	the category of hazardous goods. Please
	respect the transport directives applicable in your
	country.

Handling of Lithium Batteries:

•Store in a dry place.

•Do not heat to more than 100°C and do not throw into a fire.

•Do not store near a heat source.

•Do not store in direct sunlight.

•Do not short-circuit.

•Do not open or damage.

•Do not recharge.

•Keep out of reach of children.

1.2.2 Changing the Battery

The heat cost allocator’s battery is soldered. Changing the battery is neither provided for nor permitted.

Disposal

In order to protect the environment, to reduce waste of natural resources and prevent pollution, the European Union has adopted a directive stipulating

that electrical and electronic devices must be recovered by their manufacturers in order to ensure proper destruction or recycling.

Should you dispose of the device yourself, please get information from your local authority on recycling options.

1.2.3 Installation with Glue

Due to their chemical composition, the use of glues emits vapours and can damage the plastic casing of the heat cost allocator.

1.2.4 Warranty

The warranty rights are only valid if the devices have been installed and used in compliance with regulations and if the technical guidelines in force have been followed.

1.2.5 Compliant Use

Installation of this product must comply with the installation directives described in this manual and carried out by personnel trained for this purpose.

1.2.6 Non-compliant Use

Any application other than that described above is not permitted.

1.2.7 Notes regarding Installation

Any inappropriate handling or faulty installation may result in radiator leakage. Please respect the recommendations of the installation notice for the radiator.

1.2.8 Protection against Outside Influences 1.2.8.1 Lead seal

The heat cost allocator is closed with a safety seal which cannot be removed without causing damage. It is therefore impossible to open

the device without this being detected. After installation, the electronic part of the device is no longer accessible. The LCD display, the push button and the optical itnterface are protected. It is impossible to access the interior of the device without damaging it.

1.2.8.2 Electronic Detection of Opening

The electronic detector detects unauthorised opening and closing of the heat cost allocator. As soon as the housing of the heat cost allocator

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1.2General Guidelines is opened and / or removed, the electronic

(continuous)	detector triggers an error message. During
	this time, the date of opening of the case, the
	number of openings and the cumu-lative length
	of time for which the case was open are saved
	and may be read using the optical interface or
	the radio.
	1.2.9 Data Collection while the Device is
	open
	The heat cost allocators continue to collect data,
	even if the electronic detector is activated.

1.2.10Transport in Original Packaging

The heat cost allocators must be transported in their original packaging.

1.2.11 New Programming

Before each new instance of programming, save the history of previous value readings.

1.3 Restrictions

1.3.1 Applications

The heat cost allocators may not be used in the following cases:

•Steam heating.

•Air radiators.

•Floor heating.

•Ceiling radiant heating.

•Flap-controlled radiators.

•Radiators with a removable front plate (attached with clips).

Heat cost allocators may only be attached to radiators controlled by a combination of flaps and valves if the control is disassembled or locked in the ‘open’ position.

1.3.2Measurement using Single or Dual Sensors

Combining the two systems in the same building or in a single calculation unit is not permitted.

1.3.3 Exclusion of Liability

Danfoss rejects all liability when the conditions of assembly and use described in this manual as well as those described by the standard EN 834:2013 are not observed.

1.3.4 Modifications

Danfoss reserves the right, without prior notice, to make any modifications with a view to improving the product.

2.Product Description Contents of the SonoHCA allocator box:

2.1Packaging

	Box with label describing	5 10-piece trays with	1 box of 50 back plates	Installation guide
	the product	premounted lead seal

2.2 General Description	2.2.1 Type
	The electronic heat cost allocators SonoHCA
	operate either according to the single sensor
	principle with start sensor or the double sensor
	principle. The device has been developed and
	approved in accordance with the European
	Standard EN 834:2013.
	2.2.2 Design
	The heat cost allocator consists of a
	microprocessor, a lithium battery, two
	temperature sensors, a heat conducting
	aluminium back plate, a multi-functional display
	and a plastic housing.

The measuring circuit consists of the temperature sensors, the analogue-digital conversion, the reference resistance for standardising the measuring transformation and the microprocessor for accessing the radia-tor heat output. During each measuring the circuit tolerances are eliminated with a reference resistance and the heat cost allocator carries out an automatic self-test.

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2.2General Description

(continuous)

Standard aluminium back plate for nearly all existing bolts with common dimensions and mounting possibilities

– thus easy installation

Snap-on blind to cover colour shadows for increased aesthetics

2.2.3 Characteristics

•Measuring by two temperature sensors, radiator and ambient temperature sensor (NTC-resistor).

•Optional measuring principle: 1 sensor mode with start sensor or two sensor mode.

•Unit scale or product scale.

•Recording of cumulated heat consumption on the annual set day.

•Recording of 144 monthly values and 18 half monthly values for cumulated heat consumption.

•Recording of 18 monthly values for the maximum radiator temperature.

•Optical interface for the readout of the data and programming

•For heat cost allocator SonoHCA, the radio module comprises a unidirectional radio transmitter.

Two telegrams: short telegram, OMS compliant and long telegram for Walk-by reading.User-friendly operation by push button.

•6-digit and high-contrast LCD display.

•Automatic commissioning during the mounting on the aluminium back plate (available when ordering).

•Check code for postcard mail-in method

•Possibility to connect a remote sensor on each version of heat cost allocator. The remote sensor will be automatically detected by the heat cost allocator.

•Remote sensor version with 2 m cable.

•Standard aluminium back plate for nearly all existing bolts with common dimensions and installation possibilities – thus easy installation (no cutting and welding of bolts necessary).

•Snap-on blind to cover colour shadows for increased aesthetics.

•Safe operation and fraud/manipulation detection.

•Lithium battery with a capacity of up to 10+1 year.

•Meets EN 834:2013.

2.2.4 Display

The heat cost allocator has a LCD-display with 6 large main digits on the right and 2 smaller digits on the left as well as two special symbols and one communication indicator. The main digits are separated by four decimal points. Below, please find the display segments:

Display with all active segments

Normally, the heat cost allocators are supplied with switched-off LCD-display. On request, the heat cost allocators can also be supplied with permanent LCDdisplay.

2.2.5 Electronics

The device has an electrical circuitry with an 8-Bit-CMOS-micro controller of the latest

generation STM8L with extremely low current consumption operating at a voltage as from 1.8 V.

The temperature measuring circuit with automatic self-calibration measures the discharging time of a capacitor. The accuracy of the measuring circuit is independent of the supply voltage.

2.2.6 Versions

For each version of heat cost allocator, it is possible to plug the connector of the remote sensor to an interface inside the heat cost allocator.

Once equipped with a remote sensor, the heat cost allocator will only work for an application with remote sensor. Remote sensor version with 2 m cable.

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2.2General Description

(continuous)

2.2.7 Optical Interface

With a standardised optical probe the consumption and configuration values can be transferred directly to a computer. With the radio heat cost allocator all consumption values can be readout over the optical interface and over radio. The data are transmitted in M-bus-format acc. to EN13757-3. Authorised personnel can alter the configuration of the device over the optical interface with an optical probe.

2.2.8 Radio Wireless M-Bus

The radio heat cost allocator features a transmitter circuit in the 868 MHz band with integrated antenna.

This radio module comprises a unidirectional radio transmitter which is used to transfer data according to the wM-Bus (EN 13757-4) radio communication protocol and in compliance with the OMS (Open Metering System) Release V3.0.1.

2.3Technical data

			Single sensor device with start sensor
			for heating systems with tmmin ≥ 55 °C
			Calculation with set reference temperature 20 °C
	Optional measuring systems:		Necessary rating factors: KQ, KC, (KA, KT)
			Double sensor device
			for heating systems with tmmin ≥ 35 °C
			Calculation with variable ref. temperature T-air sensor
			Necessary rating factors: KQ, KC, (KA, KT)
	Optional scales:		Unit scale or product scale
	Current supply:		3 V-Lithium-battery
	Life-span with 1 battery:		> 10 years
	Display:		Liquid crystal display (LCD-display)
	No. of displayed digits:		6 digits (000000 ... 999999)
	Sensor temperature range:		0 °C ... 120 °C
	Exponent:		n = 1.33
	Radiator – performance range:		4 Watt ... 16.000 Watt
		(tmmin ... tmmax)	Single sensor device with start sensor
	Design temperature range:		55 °C ... 105°C / 120 °C (compact- / remote sensor)
		(tmmin ... tmmax)	Double sensor system
			35 °C ... 105°C / 120 °C (compact- / remote sensor)
	Values:		Rating factors see digital KC-data base
	Models:		Compact device or remote sensor device
	Set day:		Freely programmable
			144 monthly values and 18 half monthly values for cumulated heat
	Data storage:		consumption, 18 monthly values for the maximum radiator temperature.
			Maximum temperature of the current and previous year, all relevant
			consumption values
	Self-test:		Before every measuring
	Start of counting:		Heating period 25°C – 40°C (programmable)
			Off-heating period 25°C – 40°C (programmable)
	Satndard version:		EN 834:2013
	Homologation according to:		HKVO: A1.02.2015
	Conformity:		CE
			At 75% of the overall height of the radiator.
	Standard mounting height:		If the height of the radiator is less than (<) 470 mm, the heat cost allocator
			must be installed at 50% BH.
	Wireless M-Bus radio communication
	Frequency:		868.95 MHz
	Communication:		Unidirectional
	Protocol:		Wireless M-Bus
	Encryption:		AES-128
	Transmission standard:		EN 13757-4, mode T1
	Broadcasting interval:		Short telegram (OMS): > 120 s
			Long telegram (walk-by): > 120 s
			Short telegram (OMS): 24 h/d,
	Data transmission periods:		7 days a week
			Long telegram (walk-by): < 12 h/d,
			7 days a week

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2.3 Technical data	Dimension
(continuous)

3.	Settings	The following table can be used to determine
3.1	Settings	the configuration of the heat cost allocator by
		combining the different settings options that
		follow.

Due to distinctive technical features, not all possible combinations are necessarily achievable.

Configuration sheet for SonoHCA:

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3.1 Settings (continuous)	• Position 1: Not used.	• Position 13: Max. room temperature TA ,
	• Position 2: Allocator Date and Standard	Activation of Heat Accumulation Mode,
	Time:	Sum-mer Period:
	The UTC time zone will be programmed	Set a reference temperature in order to
	in accordance with the country where the	avoid an incorrect measurement due to heat
	allocator is in-stalled.	accumulation (e.g. if the radiator is hidden by
	• Position 3: Set Day (yearly date):	panels, thermal accumulation). The allocator
	It is possible to program an annual set day on	will automatically switch into single-sensor
	which the cumulative consumption value to	mode when the ambient temperature
	date is recorded.	measurement surpasses the defined reference
	• Position 4: Setting Winter / Summer	temperature. Following this, the calculation
	Periods:	will use an ambient temperature set to
	2 options: yes / no.	20°C rather than the temperature actually
	If the ‘yes’ option is chosen, two different	measured.
	specific heating periods (winter and summer)	• Position 14: Max. room temperature TA ,
	with different start temperatures settings	Activation of Heat Accumulation Mode,
	depending on the current period can be	Winter Period:
	distinguished.	Set a reference temperature in order to
	• Position 5: Set the Start of the Summer	avoid an incorrect measurement due to heat
	Period:	accumula-tion (e.g. if the radiator is hidden by
	Choose the date on which the summer period	panels, thermal accumulation). The allocator
	will begin.	will automatically switch into single-sensor
	• Position 6: Set the Start of the Winter	mode when the ambient temperature
	Period:	measurement surpasses the defined reference
	Choose the date on which the winter period	temperature. Following this, the calculation
	or the heating period will begin.	will use an ambient temperature set to
	• Position 7: Unit Scale and Product Scale:	20°C rather than the temperature actually
	2 options: unit scale / product scale.	measured.
	Set the type of scale used when calculating	• Position 15: Minimum Temperature
	the display values.	Difference, Summer Period:
	By default, the KC and KQ evaluation factors	Set a reference value calculated using the
	will be set to 1 for the product scale.	temperature difference between the radiator
	• Position 8: Set Cumulative Values to Zero:	and the ambient air. According to the
	2 options: set day / never.	standard EN 834: TR - TA ≤ 5 K.
	Determine whether the units’ consumption	• Position 16: Minimum Temperature
	totalizer will be reset to zero on the set day or	Difference, Summer Period:
	never.	Set a reference value calculated using the
	• Position 9: Single Sensor or Dual Sensor	temperature difference between the radiator
	Mode:	and the ambient air. According to the
	Set the measuring method used by the	standard EN 834: TR - TA ≤ 5 K.
	allocator.	• Position 17: Standard Ambient
	2 options: single sensor / two sensors.	Temperature TA, Summer Period:
	Single sensor: determines the amount of	Ambient temperature value used to calculate
	heat emitted by a radiator by measuring and	the unit’s consumption. Set by the standard
	assessing the radiator’s temperature with	EN 834: TA = 20°C.
	respect to that of the room temperature	• Position 18: Standard Ambient
	measured at the start and fixed at 20°C.	Temperature TA, Winter Period:
	Two sensors: determines the amount of heat	Ambient temperature value used to calculate
	emitted by a radiator based on the measured	the unit’s consumption. Set by the standard
	temperature of the radiator via the radiator	EN 834: TA = 20°C.
	temperature sensor and the ambient air	• Position 19: Measuring Cycle, Summer
	sensor.	Period:
	• Position 10: Elimination of Summer	Set a time interval to be used as an operations
	Counting:	measuring cycle. The allocator will therefore
	2 options: yes / no.	usually be in sleep mode.
	If the ‘yes’ option is chosen, consumption will	• Position 20: Measuring Cycle, Winter
	not be measured during the summer period.	Period:
	• Position 11: Radiator Temperature TR ,	Set a time interval to be used as an operations
	Start Counting Summer Period:	measuring cycle. The allocator will therefore
	Set the threshold temperature for the start	usually be in sleep mode.
	(counting) of the allocator. When this start	• Position 21: Commissioning of the
	temperature is reached, the allocator will	Allocator:
	begin to count the consumption units.	2 options: Automatic commissioning upon
	• Position 12: Radiator Temperature TR ,	installation on the back plate / By pressing
	Start Counting Winter Period:	the push button after installation on the back
	Set the threshold temperature for the start	plate.
	(counting) of the allocator. When this start	The allocator leaves the factory in sleep mode,
	temperature is reached, the allocator will	meaning that it does not measure or calculate
	begin to count the consumption units.	consumption. The transition from sleep to
		installation mode can be carried out in 2

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different ways: automatically upon installation on the aluminium back plate or by pressing the push button after having installed it on the aluminium back plate.

•Position 22: 24-hour Active Display:

2 options: yes / no.

If the ‘no’ option is chosen, the display will always be switched off. By pressing the push button, the LCD screen will become active. After 3 minutes of inactivity, the screen will automatically re-turn to deactivated mode.

If the ‘yes’ option is chosen, the display will be active 24 hours a day.

•Position 23: Scrolling Display Menu:

2 options: yes / no.

If the ‘no’ option is chosen (static display), the menu can be changed by pressing the push button.

If the ‘yes’ option is chosen, the display will automatically move from one menu to the next. The display duration can be configured individually for each duration.

•Position 24: Error Information Display:

If an error occurs, the Err message will appear on the LCD screen. This information will appear at the top of the menu sequence.

•Positions 25 to 39: 15 values which can be displayed.

•Position 40: Programmable Display Time for Each Value Shown.

•Position 41: Operation Mode for the Wireless M-Bus Radio:

2 options: short telegram (OMS) / long telegram (Walk-by).

•Position 42: Transmission Interval for Wireless M-Bus Radio Telegram:

Set a transmission interval for sending Wireless M-Bus radio telegrams.

•Position 43: Wireless M-Bus Radio Telegram Transmission Period.

Short telegram (OMS): 24 hours a day, 7 days a week.

Long telegram (walk-by): 12 hours chosen per day (programmable), 7 days a week.

•Position 44: AES-128 Encryption Activated at Factory:

2 options: yes / no.

If the ‘yes’ option is chosen, the encryption key can be programmed according at the customer’s request.

•Position 45: Decryption Key:

Contact the local Danfoss for Decryption Key.

•Position 46: Installer Password:

Default password: 56781234

This may be chosen by the customer.

•Position 47: Detachable Label Attached to the Heat Cost Allocator:

2 options: yes / no.

If the ‘yes’ option is chosen, a detachable label will be attached to the front face of the allocator.

•Position 48: Information Contained on the Detachable Label:

The information contained on the detachable label may be chosen by the client.

3.2 Operating mode	3.2.1 Cycle
	The heat cost allocators SonoHCA operate in a
	cycle of 4 minutes. Most of the time, the device is
	in sleeping mode. Every 4 minutes the device is
	set into operation and operates according to the
	adjoining diagram.
	The clock-pulse generator is a counter which is
	completely independent from the rest of the
	program. This counter is designed in a way so
	that it is impossible to stall the cycle or to skip
	one or more cycles.
	Each cycle follows the adjoining diagram.
	The measuring and calculating processes are
	explained in detail later.
	The tasks carried out during one cycle are taking
	approx. 100 ms. This means that the device is in
	sleeping mode more than 99.8 % of the time. It
	can be set into operation between two cycles
	over the optical probe or by pushing the button.
	In this case it carries out the requested task and
	then returns to sleeping mode.
	In case an optical probe is connected or the
	button is pushed during the course of the cycle,
	the respective value is readout at the end of the
	cycle.
	The button can be pushed for an indefinite
	period of time and the optical probe can be
	left in its position since the normal function of
	the device is not impaired by an influence from
	outside.
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3.2Operating mode

(continuous)

3.2.2 Single Sensor Version with Start Sensor

The start sensor of the single sensor version serves as an ambient temperature sensor which mainly functions during the heating up period.

The start temperature is the threshold temperature of the radiator at which the device always starts to carry out energy ratings. For these ratings, the measured radiator temperature and an assumed ambient temperature of 20° C are used as calculation basis.

3.2.3 Dual Sensor Version

For the dual sensor version basically the same specifications apply as for the single sensor version with start sensor. However, for calculating the room temperature the real temperature, measured by the ambient temperature sensor (corrected via the

corresponding radiator-dependent „Kairvalue“), is used as the basis.

3.2.3.1 Heat Accumulation Mode

In order to avoid faulty measuring due to heat accumulation (e.g. in case the radiator is hidden by panels), the device switches from a defined ambient temperature (e.g. 28°C) to the one sensor mode and calculates with an ambient temperature of 20° C.

3.2.4Comparison of the Measuring Principles

Single sensor device with start sensor measuring principle

For heating systems with tmmin ≥ 55 °C

The heat cost allocator calculates with a set reference temperature of 20 °C

Application:

Single sensor devices with start sensor are used in areas where normal ambient temperatures are given. For low temperature heating systems the double sensor device is recommended.

For radiators which are covered or blocked by fix-tures, normally the single sensor devices are used because the double sensor device is not in a posi-tion to capture the current ambient temperature due to the heat accumulation.

Double sensor measuring principle

For heating systems with tmmin ≥ 35 °C

The heat cost allocator calculates with a variable reference temperature Tair temperature

Application:

Double sensor devices are used in areas where precise measuring of the ambient temperature is necessary and/or in low temperature heating systems.

Radiators which are covered or blocked by fix-tures are detected automatically by the

double sensor system which then switches over internally to the single sensor mode.

Within one billing unit, only one measuring principle (either single sensor measuring principle with start sensor or double sensor measuring principle) can be used. Mixed fitments or the use of different types of devices in the same billing unit is therefore also not allowed.

The processes for determining the K-value for the single sensor device with start sensor and the double sensor device are identical. It is only the measuring principle that is different.

3.2.5Temperature Measurement and Calculation

The temperature is measured with an NTC – resistor. For the resistance measurement the discharging time of the capacitor is measured. The measurement is carried out as follows:

3.2.5.1 Measuring of a Resistor, Principle

1.Charging of the capacitor

2.Discharging of the capacitor through the resistance which is to be measured. At the same time a 16+1 bit-timer starts with the discharge to measure the discharging time

3.As soon as the voltage on the capacitor terminals reaches a certain value, an interrupt is induced and the timer stops. At the same time the discharging of the capacitor is stopped as well.

After the three mentioned stages, the timer provides a 16-bit-value which corresponds to the discharging time of the capacitor through the resistance which is to be measured. In case the resistance is known (reference resistance), the constant ratio between discharging time and resistance can be assessed.

3.2.5.2 Calculation of the Value of an Unknown Resistance (e.g. sensor resistance)

The capacitor C is loaded at constant current. The interrupt at the end of the discharge is triggered by the same threshold voltage (a fraction of the discharge voltage). If these two conditions are met, the discharge time is directly proportional to the resistance. With a reference resistance Rref whose exact value is known, it is now possible to calculate the unknown resistance value Rx with the following equation:

From this equation the self-calibration of the converter can be derived, which is given by measuring the discharging time through the reference resistance.

3.2.5.3 Measuring of the Radiator and Ambient Temperature

The following measurements are carried out during one cycle:

1.Measuring of the reference resistance Rref

2.Measuring of the ambient temperature sensor NTCA

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© Danfoss | 2019.03

Operating Guide	SonoHCA

3.2 Operating mode	3. Measuring of the radiator temperature sensor
(continuous)	NTCR
	The measuring values are calculated with the
	following formula:

The reference resistance value is defined ex works with a tolerance of 0.5% with 50 ppm. The reference resistance features an excellent temperature and long-term stability.

The capacitor value and the threshold voltage have to remain stable over the whole cycle. However, they can vary at the mediumor long term without causing any failures because the self-calibration of the converter is repeated

in every cycle while measuring the reference resistance.

3.2.6Calculation of the Displayed Consumption Value

The value displayed on the heat cost allocator is calculated as follows:

Single sensor device

Double sensor device

Explanation:
TH	Temperature of the radiator surface in [°C]
TA	Ambient temperature in [°C]
Q	Displayed consumption value, without
	unit
Kc	Factor that carries back the ΔT measured at
	a normalized value
Kq	Factor Kq is a numerical value of the
	nominal power of the radiator stated in
	[KW]
Unit scale:
Kc = 1		and	Kq = 1
Product scale:
Kc <> 1		and	Kq <> 1

3.2.7 Start of Counting

The updating (increment) of the consumption value is carried out under the following conditions:

During winter period (heating period): (TR ≥ 25 °C)

or

(TR ≥ 20 °C) AND (TR - TA ≥ ΔTMIN) During summer period (off heating period):

(TR	≥	35 °C)
or
(TR	≥	20 °C) AND (TR - TA ≥ ΔTMIN)
Explanation:
TR	Radiator temperature
TA	Ambient temperature
ΔTMIN	Minimum temperature difference between

radiator and room

3K for standard device (winter heating period standard setting)

4K for remote sensor device (summer heating period standard setting)

Note:

The thresholds of starting (25°C et 35°C) are indicative values. These temperatures of starting are adjusted according to the needs and specificities of the customer.

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