Danfoss DHP-R 7Ua User manual

VU*'+102
USER’S MANUAL
CONTROL SYSTEM
DHP-R&DP

VU*+'1022 – Danfoss
VUBMG102

VUBMG102
76*'+ Danfoss – 3
1 Introduction ......................................................... 5
2 Functional description ........................................ 7
2.1 Heating.................................................................... 7
2.1.1 Primary supply temperature..............................................................7
2.1.2 Integral control.......................................................................................7
2.1.3 Auxiliary heater ......................................................................................8
2.1.4 Seasonal stop........................................................................................10
2.1.5 Room temperature feedback and curve displacement.........10
2.1.6 Temperature limits and forced starts and stops.......................11
2.2 Hot water ..............................................................11
2.2.1 Basic settings.........................................................................................11
2.2.2 System settings ....................................................................................12
2.2.3 Hot water production ........................................................................12
2.2.4 Top-Up function...................................................................................12
2.2.5 Systems with hot water heat exchanger and WCS..................12
2.2.6 Final hot water heater with TWC....................................................13
2.3 Heat pump restrictions........................................13
2.3.1 Time restrictions...................................................................................13
2.3.2 Return temperature............................................................................13
2.3.3 Brine flow guard / pressure guard.................................................13
2.3.4 Brine monitoring..................................................................................14
2.4 Shunt groups ........................................................ 14
2.4.1 Outdoor compensated curve..........................................................14
2.4.2 Curve with seasonal stop..................................................................14
2.4.3 Constant heat........................................................................................15
2.4.4 Constant cooling..................................................................................15
2.5 Cooling.................................................................. 15
2.5.1 Cooling tank and integral control..................................................15
2.5.2 Surplus heat dumping.......................................................................16
2.5.3 The cooling circuit controller ..........................................................17
2.5.4 Blocking cooling ..................................................................................17
3 Using the controller........................................... 19
3.1 The operator panel...............................................19
3.2 Menus....................................................................19
3.3 Alarms ...................................................................20
3.4 Operation mode ................................................... 21
3.5 Information........................................................... 21
3.6 Settings .................................................................21
3.6.1 Heat pump .............................................................................................21
3.6.2 Heating....................................................................................................23
3.6.3 Extra heater............................................................................................24
3.6.4 Heat stop.................................................................................................24
3.6.5 Brine control..........................................................................................25
3.6.6 Hot water................................................................................................25
3.6.7 WCS...........................................................................................................26
3.6.8 TWC ..........................................................................................................26
3.6.9 Shunt groups.........................................................................................27
3.6.10 Cooling ....................................................................................................27
3.6.11 Manual override...................................................................................29
3.7 Expansion modules..............................................29
3.7.1 Slave pumps ..........................................................................................30
3.7.2 WCS, TWC, and Cooling.....................................................................30
3.7.3 Shunt groups.........................................................................................30
3.8 System settings .................................................... 30
3.8.1 Serial number........................................................................................30
3.8.2 Menu navigation..................................................................................30
3.8.3 Clock.........................................................................................................31
3.8.4 Password.................................................................................................
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3.8.5 Network...................................................................................................31
3.8.6 Email.........................................................................................................31
3.8.7 Sms............................................................................................................
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3.8.8 Restart......................................................................................................31
3.8.9 Factory settings....................................................................................31
3.8.10 Local backup..........................................................................................32
3.8.11 Version numbers..................................................................................32
3.8.12 Software upgrade................................................................................32
3.8.13 Restore passwords...............................................................................32
3.9 Language ..............................................................32
4Commissioning .................................................. 33
4.1 Basic settings........................................................33
4.1.1 Master or slave......................................................................................33
4.1.2 Settings in each heat pump.............................................................33
4.1.3 Extra heater............................................................................................33
4.1.4 Expansion modules.............................................................................33
4.1.5 Cooling ....................................................................................................34
4.2 Testing the installation........................................ 34
4.2.1 Sensor verification...............................................................................34
4.2.2 Checking actuators .............................................................................34
4.3 Starting the controller .........................................35
4.4 Fine tuning............................................................35
5 External and superior control systems................ 37
5.1 OPC-server for connection to SCADA-systems ..37
5.2 Alarm management and e-mails.........................37
5.3 Control by external PLC .......................................37
5.4 The sum alarm relay output ................................ 38
6 List of alarms ...................................................... 39
7 Digital inputs and outputs................................ 41
8 Menu overview................................................... 43
Contents
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Clear alarm log.........................................................................................32

76*'+4 – Danfoss
VUBMG102

VUBMG102
76*'+ Danfoss – 5
1 Introduction
WM HPC is the control system that is mounted in and controls the heat. The
control system can work in either master or slave mode. One pump in each
plant, which can consist of one to eight heat pumps, must be configured as the
master. In addition to controlling slave heat pumps, a control system in master
mode can control expansion modules for a hot water charge system (WCS),
tap water control (TWC), cooling, and up to eight shunt group modules.
The WM HPC designated as the master controls the plant’s primary supply
temperature. An outdoor temperature sensor, a primary supply temperature
sensor, and the system primary circulation pump are all connected to the mas-
ter control system.The master can also control auxiliary heating, which may be
electrical, district heating, or oil or another kind of burner.
WM HPC has an operator panel on the front of the heat pump where the user
can see and change settings, alarms, temperature set points, etc. WM HPC also
has a web based user interface that is unlocked by purchasing a licence. The
web interface makes it possible to monitor the plant and adjust settings over
a network, modem, or the Internet from any computer with a web browser.
With the web interface unlocked it is also possible to receive alarms from the
controller by e-mail.

76*'+6 – Danfoss
VUBMG102

VUBMG102
76*'+ Danfoss – 7
2 Functional description
2.1 Heating
2.1.1 Primary supply temperature
The heating control inWM HPC allows a building to be maintained at a comfor-
table temperature. It controls one or more heat pumps that produce heat, and
can also start auxiliary heating when necessary.The primary supply is the pipe
that provides heat to the building’s radiators and other heat consumers.
The primary supply is maintained at a temperature that is based on the outdo-
or temperature. This temperature is measured and the desired primary supply
temperature is looked up in a curve.This curve must be adjusted to fit the tem-
perature needs of the specific building it is to control. The temperature that is
looked up is used as a set point for the integral control.
2.1.2 Integral control
The integral control decides whether the heat pump, or several heat pumps,
should run, and also if the auxiliary heater is needed. A heat pump can only
be either on or off, and will therefore produce too much or too little heat. The
goal for the control system is to produce just enough heat to keep the primary
supply temperature close to the set point.
The integral value is calculated by adding the difference between the primary
supply temperature and the set point to the integral every minute.The integral

76*'+8 – Danfoss
VUBMG102
therefore has the unit degree minutes and represents the plant’s energy ba-
lance. If the primary supply temperature is one degree above the set point for
one hour straight the integral value will grow to 60. If the supply temperature
is too low, the integral value will decrease and become negative. When the
temperature is precisely right the integral will not change at all.
There is a setting in the controller called Start hp1. This setting is for the inte-
gral value at which the first heat pump should start. It is a negative number.
When the heat pump starts, it may be that it produces more heat than neces-
sary. The integral value will then increase, and when it passes zero the heat
pump is turned off. The primary supply temperature will, at average, have had
the same temperature as the set point. Since a building’s temperature changes
slowly, the variations in the primary supply will not make a noticeable diffe-
rence in room temperature.
The setting Delta start hp decides how much below Start hp1 the integral must
drop before the next heat pump is started, and how much below that before
the third starts, and so on, if the plant has multiple heat pumps.
If all the heat pumps are running but the integral still drops, then the auxiliary
heater is needed. Start extra heater decides how much below the starting va-
lue for the last heat pump the integral must drop before the auxiliary heater is
started. When it has dropped to the limit Full extra heater below the start limit
or the last heat pump, the auxiliary heater will work at maximum power. Exac-
tly how the auxiliary heater works depends on what type it is.
The integral is allowed to drop a little bit more according to the setting Integral
dead zone, but then it is not allowed to become lower. On the positive side it is
limited by the setting Integral max limit.
The integral value can be read on the pump display.
2.1.3 Auxiliary heater
The control system has one relay output Block. extra heater and one analogue
0 to 10 V output Extra heater, which can be used to control auxiliary heating of
different types. When the plant is commissioned, the type of auxiliary heater, if
any, is defined in the control system.
2.1.3.1 Burner
The auxiliary heater can consist of a burner for oil, gas, wood chips, or some
other fuel. The burner must have its own control system and be capable of ge-
nerating a constant high water temperature. The signal Block. extra heater can
be used to turn off the burner completely. The analogue signal Extra heater

VUBMG102
76*'+ Danfoss – 9
controls a shunt valve that shunts out as much heat as needed from the burner
subsystem.
The blocking of the burner is released when the integral reaches the limit for
starting the auxiliary heater. When the burner starts it may be full of fairly cold
water, and it will take a while for the burner to achieve the right water tempe-
rature. The shunt valve is therefore locked in the closed position for a period
of time defined by the setting Heat up delay. After that time the burner is as-
sumed to be able to deliver energy.
The shunt valve is controlled proportionally, so that it is fully open when the
integral has reached the limit for full auxiliary heat and is closed when at the
start limit.
When the shunt valve has been closed for a certain time it is reasonable to be-
lieve that the burner won’t be needed for a while. It is turned of by the signal
Block. extra heater. How long the delay should be before the burner is turned
off is decided by the setting Burner off delay.
2.1.3.2 Electrical heater
An auxiliary heater in the form of an electrical heater with only one power
setting is controlled using the signal Block. extra heater. The heater is started
when the integral passes the limit for starting the auxiliary heater, and is tur-
ned of when it rises above the limit for starting the last heat pump.
When the heater is started it is controlled not only by the integral, but also by
the controller error. If the difference between the primary supply temperature
and the set point is greater than the value Turn off limit, the heater is turned
off. As long as the integral value is not above the start limit for the last heat
pump it is turned on again if the controller error goes below Turn on limit.
2.1.3.3 0 to 10 V
If the auxiliary heat comes from a district heating network, the WM HPC con-
trols a shunt using the analogue signal Extra heater. This mode of auxiliary heat
can also be used for other types of heaters that can be controlled with a pro-
portional signal. One example is electrical heating with multiple power steps
controlled by an analogue input.
The signal Extra heater is at 100% (10 V) when the integral has reached the
auxiliary heater maximum limit and is zero at the auxiliary heater start limit.
A district heating system will usually not need the signal Block. extra heater,
but it is still available. The blocking is lifted when the integral passes the auxi-
liary heater start limit, and is blocked again when it rises above the start limit
for the last heat pump.

76*'+10 – Danfoss
VUBMG102
2.1.4 Seasonal stop
During the warm season there is usually no need to warm the building. Howe-
ver, the outdoor temperature may temporarily (at night time) fall enough for
the control system to start a heat pump. To avoid this, the functions for seaso-
nal stop can be used.
When the outdoor temperature is persistently above the limit Heat stop limit
seasonal stop is activated. This means that no heat pumps are allowed to pro-
duce heat, and the auxiliary heater is blocked. Furthermore the main circula-
tion pump is stopped.
What is meant by persistently is defined by the time limit Activation time lim.
In order for the seasonal stop to be released, the outdoor temperature must be
at least Heat stop hyst degrees below Heat stop limit for at least Deactiv. time
lim hours.
The seasonal stop could cause the main circulation pump to stand still for a
long time. There is therefore a pump exercise function. Once every day the
circulation pump is started and run for one minute. The pump exercise times
can be adjusted.
The auxiliary heater can be blocked earlier, at lower temperatures. There is a
separate outdoor temperature limit and hysteresis for blocking the auxiliary
heating, but without the time limits.
2.1.5 Room temperature feedback and curve displacement
It is possible to connect a room temperature sensor to the control system for
the master pump. Using the room temperature feedback function, the primary
supply temperature set point can be adjusted if the indoor temperature gets
too warm or too cold.
In the controller, the desired room temperature is set Room set point and the
feedback strength is adjusted. Zero deviation in the curve Curve room temp
feedback corresponds to a perfect room temperature. It is a good idea to not
have any curve adjustment for deviations close to zero, in order to avoid self
excitation.

VUBMG102
76*'+ Danfoss – 11
The room temperature feedback function can be complemented with a time
based adjustment of the room temperature set point. In the week schedule
Calendar room temp desired time periods when a different temperature set
point is desired can be entered. How much the set point is to be adjusted is
entered in the setting Calendar offset.
The setting Curve offset provides a mean to manually shift the whole set point
curve for the primary supply temperature, affecting the set point equally for all
outdoor temperatures.
2.1.6 Temperature limits and forced starts and stops
The primary supply set point curve, together with room feedback and manual
adjustment, can result in virtually any value for the primary supply set point. In
order to ensure that the primary supply temperature stays within reasonable
limits there are settings for how high and low the set point may be. These set-
ting are Max system temp and Min system temp.
The integral changes relatively slowly. After a system restart, for example after
a power failure, it may take a while for heat production to start, as the integral
starts at zero. In order to speed up the heating after a restart it is possible to
activate forced start conditions. If the primary supply temperature falls more
than Lim force hp start degrees below the set point, the integral is forced to
the starting value for the first heat pump, unless that limit has already been
passed. If the controller error falls below Lim force eh start, the integral is set to
the start auxiliary heater limit.
Forced stops works in a similar way when the primary supply temperature gets
significantly higher than the set point. The auxiliary heater is stopped when
the controller error is two degrees below Lim force hp start. The heat pumps
are stopped exactly at the Lim force hp start limit.
The forced starts and stops are inactivated if these settings are set to zero.
2.2 Hot water
2.2.1 Basic settings
Every pump has a setting that decides whether it can be used to make hot
water or not. Heat pumps that can produce hot water have a switchover valve
that switches from heat production to hot water production.
The factory setting is that hot water production is stopped when the opera-
ting pressure switch is triggered. This setting can be changed so that it instead
stops when a temperature limit is reached.

76*'+12 – Danfoss
VUBMG102
2.2.2 System settings
The master pump controller contains settings to define whether the plant uses
double jacketed hot water heaters or a heat exchanger. If the plant uses a heat
exchanger, the WCS module is needed.
2.2.3 Hot water production
The sensor Hot water start sensor measures the temperature of the water go-
ing in to the hot water heater. When this falls below a certain limit (Start limit)
a hot water pump is started to produce hot water. Hot water production has
priority over building heating, so if there is a pump already running to heat the
building it switches over to produce hot water.
If the temperature continues to drop, more heat pumps are used to produce
hot water. The setting Delta limit next hp decides how much the temperature
is allowed to drop between each heat pump start.
If the heat pumps are set to stop producing hot water at a certain tempera-
ture, they will be stopped in the same manner as they were started as the hot
water heating temperature starts to reach the Stop limit setting. However, the
default setting is that the pumps continue to produce hot water until the ope-
rating pressure switch is activated.
When a heat pump stops producing hot water it will instead produce heat for
the building, if there is a demand for heat.
2.2.4 Top-Up function
Before hot water production is turned off, the Top-Up function performs a check to
see whether it can top up the hot water first. If the hot water temperature is lower
thanTop up temp limit degrees over the start limit Start limit it will produce hot wa-
ter instead of stopping immediately. TheTop-up function is by default inactivated.
2.2.5 Systems with hot water heat exchanger and WCS
The WCS-module measures one charge temperature Wcs temperature and
controls one charger circulation pump and one valve.
If the heat pump hot gases are used for hot water production the hot gas fun-
ction should be activated. This causes the charger pump to always be on. Oth-
erwise it runs only when the heat pump is producing hot water.
When the charger pump is running the valve is controlled to keep the char-
ge temperature constant. Directly after the charge pump is started the valve
opens fully, and is kept fully open for a number of seconds defined in the set-
ting Wcs ctrl start delay.
The set point for the charger temperature is defined in the setting Wcs set-
point. The controller is a PD-controller with the controller parameters Wcs p-
area and Wcs d-factor.

VUBMG102
76*'+ Danfoss – 13
2.2.6 Final hot water heater with TWC
The TWC (Tap Water Control) module monitors and controls an electrical hot
water heater to ensure that the water at the tap points is the right temperature.
The module controls the electrical heater and measures temperatures on both
the outgoing water and the re-circulated water. If either of these temperatures
falls outside the set limits alarms are generated.
When the heater starts and stops is decided by high and low limits on both the
outgoing and re-circulated water. The upper limit for outgoing temperature
has the highest priority to avoid burn hazards. Different start delays are used
for the outgoing and return temperature limits.
A special legionella function is designed to ensure that all legionella bacteria
in the final heater are killed. A week schedule defines when to start a legio-
nella heat run. When started the heater will be on until the water reaches the
legionella stop temp. The week schedule is not activated in the factory default
setting, but can be set to run once a week if heater seldom reaches high tem-
peratures in normal operation.
2.3 Heat pump restrictions
2.3.1 Time restrictions
The heat pump has two time conditions that must be met if it is to be allowed
to start. One states that when stopped it must be standing still for at least five
minutes before it can start again. The other states that any two starts must be
at least 20 minutes apart. This time limit can be changed using the setting Min
start interval.
The display on the pump shows whether it is blocked by a time condition, and
how many seconds are left until it is allowed to start again.
2.3.2 Return temperature
If the temperature on the pump return reaches a threshold, an alarm is gene-
rated and the pump stops. This alarm is inactivated when the pump is making
hot water, and the alarm does not prevent the pump from making hot water.
The default setting for the threshold is 48 °C.
2.3.3 Brine flow guard / pressure guard
In each heat pump there is a setting that tells whether the brine flow is moni-
tored by an external flow guard or pressure guard. If a flow guard is activated
there is an alarm with an adjustable delay that stops the pump on error.
If the pressure guard is selected a choice can be made whether the alarm
should stop the pump or not.

76*'+14 – Danfoss
VUBMG102
2.3.4 Brine monitoring
In the master pump controller a function for brine monitoring can be activa-
ted.This function can be used, for example, to avoid very low brine temperatu-
res, to prevent freezing on the tubing.
The brine temperature sensors on all running pumps are used in the monito-
ring. For outgoing brine there is a low temperature limit. For incoming brine
there is both a low and a high temperature limit. If any of these limits are bro-
ken for a preset period of time a temperature violation has occurred. The num-
ber of running heat pumps is then limited to one less than those currently
running. If the temperature violation persists, the number of running pumps
is limited further.
When the temperature violation ceases, the limitation is gradually lifted.
2.4 Shunt groups
Up to eight shunt modules can be connected to
the control system. A shunt module can control
one circulation pump and one shunt valve, and
measure one temperature. The purpose of the
shunt module is to control the measured tem-
perature using the shunt valve. The functiona-
lity can be configured for the cases described
below.
The controller is a PI-controller. An alarm is ge-
nerated if the controller error exceeds a setta-
ble limit.
2.4.1 Outdoor compensated curve
If the outdoor compensated curve function is
selected for the shunt group, the controller set
point will be dependent on the outdoor tem-
perature. A curve is used to define different set
points for different temperatures.
The circulation pump and the shunt valve will be closed if the outdoor tempe-
rature exceeds the limit Shunt 1 outdoor temp. stop. The pump and the con-
troller are started again when the outdoor temperature falls below the limit
with a hysteresis. While stopped the circulation pump is exercised at regular
intervals.
2.4.2 Curve with seasonal stop
Curve with seasonal stop is the same functionality as is used in the outdoor
compensated curve, but with the difference that it uses the master heat pump’s

VUBMG102
76*'+ Danfoss – 15
settings for seasonal stop to stop the circulation pump and shunt controller.
When this functionality is selected, there are no individual stop limits for the
shunt group.
2.4.3 Constant heat
Constant heat is used to maintain a constant temperature, independent of the
outdoor temperature. In all other respects, the functionality is equivalent to
that of the outdoor compensated curve.
2.4.4 Constant cooling
Constant cooling is used to control a cooling circuit at a constant temperature.
This function is similar to that for constant heat, but is designated for cooling.
This means that the circulation pump and controller are stopped when the
outdoor temperature falls below a configurable stop limit.
2.5 Cooling
With a cooling system the cold side of the heat pumps are used to generate
comfort cooling, or cooling for other purposes.To control a cooling system the
module HPC-CM is used.
2.5.1 Cooling tank and integral control
A cooling tank is used to store chill water. The temperature in the tank is me-
asured and compared to a set point.The difference is integrated, and just as for
heat production the cooling integral is used to control how the tank is cooled.
When the temperature in the cooling tank gets too high the integral becomes
more positive. When the cooling integral passes the limit Start passive cool.
the system begins cooling the tank using passive cooling. This means that the
brine is circulated through the cooling tank and the bore hole without any
heat pump being started. The energy from the cooling tank is transported to
the bore hole.
A prerequisite for passive cooling to work is that the brine temperature is lower

76*'+16 – Danfoss
VUBMG102
than the temperature in the cooling tank. The limit Temp diff limit defines how
much cooler it has to be for the valve to the tank to open. There is also a delay
from the start of the brine circulation pump to the opening of the valve, so that
cold brine fluid has time to be pumped up from the hole.
As the cooling integral passes the limit for active cooling a heat pump is star-
ted. The heat pump will lower the temperature on the brine before it enters
the cooling tank. If the integral continues to rise, more heat pumps will be
started.
The valve for active cooling will change position and disconnect the bore hole.
The brine will then circulate only through the cooling tank and the heat pumps,
so that maximum heat is removed from the cooling tank.
2.5.2 Surplus heat dumping
The heat produced when a heat pump is started for cooling is, as a first option,
used to make hot water or to warm the building, if such demands exist. When
these demands are met, the heat has to be dumped. This can be done in two
ways. One way is to move the heat from the heat pumps warm side, through a
heat exchanger, over to the brine and store it in the bore hole.The other option
is to vent it away using a surplus chiller. The surplus chiller is activated by the
Config cooling setting.
If the surplus chilleris used, a PI-controller is used to control cooling fans, with
settings for set point, P-area, and I-time.

VUBMG102
76*'+ Danfoss – 17
2.5.3 The cooling circuit controller
A cooling circuit is used to move the cold from the cooling tank to where it is
needed. A shunt valve and a controller keep the temperature on the cooling
circuit constant. This controller has settings for set point, P-area, and I-time.
The HPC-CM module has inputs for a humidity sensor that measures both
room temperature and relative humidity. When connected, the dew point con-
trol can be activated.The control system will then calculate the dew point, and
if necessary raise the cooling circuit set point to avoid condensation.
2.5.4 Blocking cooling
The cooling circuit can be blocked by low outdoor temperature. A tempera-
ture limit, with hysteresis, blocks the use of active cooling. Another limit blocks
passive cooling. When passive cooling is blocked, the cooling circuit controller
and circulation pump are stopped.The circulation pump is exercised at regular
intervals.

76*'+18 – Danfoss
VUBMG102

VUBMG102
76*'+ Danfoss – 19
3 Using the controller
3.1 The operator panel
The operator panel on the front of the pump has a display, a six button keypad,
and two indicator LEDs.The green LED indicates that the control system for the
heat pump is running and working. If it is blinking the display is powered, but
it cannot communicate with the control computer.
When the system is running, the arrow keys are used to navigate menus and to
change settings.The Ok-button is used to enter a menu, and to start and finish
the editing of a setting. The escape button is used to back out from a menu
and to abort editing without saving the value.
The red alarm LED is lit when an alarm is active. If there are alarm that needs to
be acknowledged the LED will blink.
When the operator panel is started it first runs a “boot loader” software. This
software waits until it can communicate with the control system and checks if
the main program needs to be updated. During this time the red LED will blink
very fast. If the main operator panel program looses communication with the
control system for a minute or more it will start the boot loader again.This hap-
pens if the WM HPC is restarted.
3.2 Menus
On the top level there are 11 menus that you can scroll through using the left
and right arrow keys. In the controller for a slave pump there are fewer menus.

76*'+20 – Danfoss
VUBMG102
If you don’t touch the buttons on an operator panel for 15 minutes, it will enter
a basic mode where it shows an overview menu. In the controller for a master
pump it will alternate between three overview menus. If an alarm becomes
active, the active alarms menu is shown.
The menus Heat pump state, Master state, and Hp overview are overview me-
nus. It is not possible to use the up and down arrow keys in these menus. A
slave heat pump has only the Heat pump state overview menu.
In the other menus, Active alarms, Alarm history, Operation mode, Informa-
tion, Settings, Accessory modules, System settings, and Language, individual
menu elements can be selected using the up and down arrow keys. The active
menu element will be indicated by underlining. Sub menus are written in capi-
tal letters and marked with … A selected sub menu is opened when Ok is pres-
sed. If the selected menu element is a value or setting that can be changed,
the editing mode is entered when Ok is pressed. The value to be edited then
starts to blink, and is changed using the up and down arrow keys. Some values
can only be increased or decreased; others are edited one number or letter at a
time. Select the number to edit using the right and left arrow keys. To end and
save an edit, press the Ok button. To abort, press escape.
To return to a menu on a higher level, press escape.
3.3 Alarms
The menu Active alarms shows all the alarms that are currently active, if there
are any. The alarms monitor the occurrence of errors. Some alarms indicate se-
rious malfunctions that may cause the heat pump to be damaged, or disabled.
These alarms are classified as A-alarms, and the heat pump cannot run as long
as an A-alarm is active. Other alarms are classified as B-alarms, which does not
necessarily mean that the fault is not serious, but it will not prevent the heat
pump from starting.
Alarms can work in three different ways. Some alarms need to be acknowled-
ged before they becomes inactive. Before acknowledging, make sure that the
fault causing the alarm has been corrected. Other alarms will automatically
become inactive when the fault condition is gone. The third kind of alarm will
automatically become inactive, but will remain in the list of active alarms until
acknowledged. This is to make sure that the operator notices the event.
If one alarm in the list of active alarms is selected and Ok is pressed, more in-
formation about that alarm is displayed. Press Ok again to acknowledge the
alarm. The operator acknowledging an alarm gets the opportunity to enter a
signature of up to three letters.
In the menu Alarm history all alarms, events and errors that have occurred la-
tely can be seen. One alarm at a time is displayed in chronological order, with
the most recent displayed first. Change the displayed alarm using the up and
down arrows. Alarms are first noted in the list when they become active, and