Danfoss SonoHCA Installation guide
Installation Guide
LC-Display
Optical Interface
Push Button
Seal
Electronic Heat Cost Allocator
SonoHCA
1 Specification
1.1 General Description
1.1.1 Type
1.1.2 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
The electronic heat cost allocators SonoHCA
operate with the double sensor principle. The
device has been developed and approved
in accordance with the European Standard
EN 834 :2013.
conversion, the reference resistance for
standardising the measuring transformation and
the microprocessor for accessing the radiator
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.
Standard aluminium back plate
for nearly all existing bolts with
common dimensions and mounting
possibilities – thus easy installation
© Danfoss | 2019.05 VI.SH.R1.02 | 1
Snap-on blind to cover
colour shadows for
increased aesthetics
Installation Guide SonoHCA
1.1.3 Characteristics
1.1.4 Display
• Measuring by two temperature sensors,
radiator and ambient temperature sensor
(NTC-resistor).
• 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
• 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
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. Please find
the display segments:
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
necessar y).
• 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.
88
888888
1.1.5 E lec tronics
1.1.6 Optical Interface
Normally, the heat cost allocators are supplied
with switched-off LCD-display. On request, the
heat cost allocators can also be supplied with
permanent LCD- display.
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.
With a standardised optical probe the
consumption and configuration values can
be transferred directly to a computer. All
consumption values can be readout over the
optical interface and over radio. The data are
Display with all active segments
For SonoHCA it is possible to plug the connector
of the remote sensor to an interface inside the
heat cost allocator. Refer to chapter 2.3 Mounting
the Remote Sensor.
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.
transmitted in M-bus-format acc. to EN136757-3.
Authorised personnel can alter the configuration
of the device over the optical interface with an
optical probe.
1.1.7 Radio Transmission
wM-Bus
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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.
• Please refer to chapter 1.7.4 Operation Mode
for Radio wM-Bus (SonoHCA) for the radio
reading range.
Installation Guide SonoHCA
Start of cylce
Measuring and
calculation of the
temperature
Calculation of the
new consumption
value
Update time and
date
End of cycle
Update display
1.2 Operating mode
1.2.1 Cycle Time
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.
1.2.2 Double Sensor real temperature, measured by the ambient
1.2.2.1 Heat Accumulation
Mode
For the double sensor version basically the
same specifications apply as for the single
sensor version with start sensor. However,
for calculating the room temperature the
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
temperature sensor (corrected via the
corresponding radiator-dependent „K
is used as the basis.
sensor mode and calculates with an ambient
temperature of 20 °C.
-value“),
air
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Installation Guide SonoHCA
NTC
1.2.3 Comparison of the
Measuring Principles
1.2.4 Temperature
Measurement and
Calculation
1.2.4.1 Measuring of a
Resistor, Principle
Double sensor measuring principle
For heating systems with tm
≥ 35 °C
min
The heat cost allocator calculates with a variable
reference temperature T
air 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
fixtures are detected automatically by the
double sensor system which then switches over
internally to the single sensor mode.
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:
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.
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.
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.
1.2.4.2 Calculation of
the Value of an Unknown
Resistance (e.g. sensor
resistance)
1.2.4.3 Measuring of
the Radiator and Ambient
Temperature
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 dis-charge time is directly proportional
to the resistance. With a reference resistance R
whose exact value is known, it is now possible to
ref
calculate the unknown resistance value Rx with
The following measurements are carried out
during one cycle:
1. Measuring of the reference resistance R
2. Measuring of the ambient temperature
sensor NTC
3. Measuring of the radiator temperature
sensor NTC
A
R
ref
The measuring values are calculated with the
following formula:
t
NTC
A R
R TC
= ⋅ = ⋅ N
A
t
ref
ref R
t
NTC
R
ref
t
ref
the following equation:
tRt
ref
= ⇒ = ⋅
R
refXX
From this equation the self-calibration of the
converter can be derived, which is given by
t
X
R
R
X
ref
t
ref
measuring the discharging time through the
reference resistance.
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 medium- or long
term without causing any failures because the
self-calibration of the con-verter is repeated
in every cycle while measuring the reference
resistance.
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Installation Guide SonoHCA
= ∗∫ (
−
60
)
1.33
1.2.5 Calculation of the
Displayed Consumption
Value
1.2.6 Start of Counting
The value displayed on the heat cost allocator is
calculated as follows:
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
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 ) E (TR - TA ≥ ΔT
MIN
)
During summer period (off heating period):
(TR ≥ 35 °C)
Or
(TR ≥ 20 °C ) E (TR - TA ≥ ΔT
MIN
)
Explanation:
TR Radiator temperature
TA Ambient temperature
ΔT
Minimum temperature difference
MIN
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
adjust-ed according to the needs and specificities of
the customer.
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Installation Guide SonoHCA
LC-Display
Optical Interface
Push Button
Seal
1.3 Display and
Additional Functions
1.3.1 The Menu
Sequences of the Digital
Display
The menu sequences
Ex factory all menu sequences are activated.
With a software the order of the menu
sequences 1 - 15 can be changed in any order.
However the order within the individual menu
sequences 1 – 15 cannot be changed. It is also
possible to hide individual menu sequences so
that they are not visible to the end-user.
When reading out over the optical interface
or via radio the complete set of data is always
readout and transferred.
Operation of the Push Button
When pushing the button briefly the digital
display always goes to the next menu sequence.
When pushing the button in one menu sequence
for 2 seconds the individual values within the
selected menu sequence can be accessed. When
the last value within one menu sequence has
been displayed, the 1st position will be displayed
by pushing the button again.
If the button is not pushed for 2 minutes,
the digital display returns to the cumulated
consumption value.
Consumption value
36 Monthly Values
Short key press
Current time
Short key press
Current date
Short key press
Set Day value
Short key press
Radiator temperature
Display position 1
Long key press
Display position 2
Display position 3
Display position 4
Display position 5
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