Samsung RC090MHXEA User manual

www.freedomhp.co.uk ©G Hendra Nov 18 1
This is the Freedom Heat pumps service manual for Samsung
air sourced heat pumps from 2010 – 2015.
Its all the work of Freedom Heat Pumps, if you like it and
would like a version for the current units you need to come on
service partner training click here.
https://www.freedomhp.co.uk/training/
Samsung Eco Heating System 2010-15
Service Manual
Model Numbers:
RC090MHXEA and RC160MHXEA

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Self-Test mode
With the power OFF, remove the front of the remote
controller, slide it upwards, turn it over
DON’T TOUCH THE PCB, there are 8 dip switches
near the red sensor, using a small
screwdriver flick dip switch 1 and 5 to on. Cooling will
no longer be available and test run will be activated.
Put the controller back on the wall.

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Exit test mode – hold the Cancel/Delete button for 6 seconds to go back to normal display
Operation Button Display
Enter test mode – hold Blue set button and the Test button together for 5
seconds
Run the water circulation pump (B6 live) – Press the Heating on/off button
Run the Backup heater/boiler (B2 live) – press the Mode button (Heating)
Run the immersion heater (Terminal A3&A4) – press the Weekly button
Run the Hybrid Boiler (B4 live) – press the Set button
Open the Hot Water Zone Valve (B8 live) – press the Lock Button
Open valve for heating Zone 1 (B12 live) – press the DHW on/off button
Open valve for heating Zone 2 (B16 live) – press the Mode button (DHW)
Show 5 temperature sensor values in order – press the View button.
Return temperature
Flow temperature (From heat pump)
Flow temperature (From hybrid boiler)
Hot water cylinder temperature
Temperature of the inside of the house
Run signal coming back from heating zone 1 thermostat into terminal B22
Run signal coming back from heating zone 2 thermostat into terminal B24

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On the main
MIM control
PCB there are
7 orange leds
above the
relays
When lit:
Led 500 immersion heater A4 live Led 501 backup heater stage 1 B2 live
Led 502 backup heater stage 2 B3 live Led 503 backup boiler (hybrid) B4 live
Led 504 pump running B6 live Led 505 Hot water valve open B10 Live
Led 506 Zone valve 1 closed B14 off Led 507 zone valve 2 closed B18 off

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What makes the unit go?
When operating the unit measures the water flow and return temperatures across the
outdoor heat exchanger. T/S 2 and T/S1 in the diagram below.
If the delta T (temp difference across T/S1 and T/S2) is 5 degrees C the unit is
happy, this is its main control feature.
If T/S 2 (flow) is less than 5 c above T/S1 (return) the unit is providing too much heat
so the compressor will slow down reducing capacity.
If T/S 2 (flow) is more than 5 C above T/S1 (return) the unit needs to work harder so
it will rev up.

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Interogating the outdoor unit
Using the 4 buttons at the bottom of
the main PCB on the outdoor unit
PCB you can run the units in test
modes
Normal display Is flashing between
AdFO-0000-
Button K3 resets the unit, it’s a quick way of resetting the power.
By pressing button K4 you enter the service mode, here you can monitor the units operation.
Note there are 16 pieces of data, one for each time you press the button K4, to exit press K3.

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My unit seems to be struggling and is freezing up?
In cold weather we get reports that units are freezing up excessively or the unit is not
achieving high enough radiator and floor temperatures:
This can be caused by the unit having a fault or it not being big
enough for the job.
Firstly, we will test if the unit is working ok:
First draw off 30 liters of water from the cylinder, run a couple of
taps for 5 mins to achieve this.
The heat pump should be able to achieve a 48C flow temperature
without using the immersion heater if it’s working ok.
If it’s struggling to reach the 48C it might be a refrigerant or a flow
problem
Note it takes the tank much longer to heat up than normal, especially when the tank
temperature is high. And it takes a lot more power to do this.
If the unit can meet the tank temperature the heat pump is ok. Now we have to make some
more tests.
If its struggling to heat the house firstly take field setting 2091 and 2092 out of the system set
them to 0. Now running the unit at a constant temperature test the unit at a 50C flow
temperature. If it can’t make 50 C against the heat pump is probably not big enough.
To prove this if you close of half of the heating circuit you will see the flow temperature can be
met. If this happens you need to get out your heat loss calculation and check it’s been done
correctly.
The next thing to check is the flow rate. If the flow rate is low the unit will not achieve its
maximum potential. Size 16 units need 30l/min, size 9 units need 20l/min.
If the unit can’t make 48C flow you need to do a performance
test, this is done using the service partner tool excel.
Call our office 02380 274833 with the following info:
Unit model and serial number
The flow and return temperatures
The flow rate
Using outdoor unit function (press k4) see page 2
No 2 compressor speed and no 5 compressor outlet temperature.

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Also see E231 it could be the coil sensor reading a high
temperature.
Not enough hot water
If it is reported that the temperature of the hot water is too low a few
tests need to be made.
Make sure the tank sensor is in the pocket 1/3 of the way from the top
of the cylinder, it must be above the immersion coil.
The tanks sensor
needs to go 115mm
into the tank into one
of the pockets inside,
it must be clipped so
it can’t pull out.
Make sure the tank temperature is set to 48C on the remote
controller, press blue set button until the tap symbol appears
and set it to 48C with the silver up button.
Press the blue view button you can see 4 sensor readings,
press it until the tap symbol shows. This is the tank
temperature. It will display for about 10 seconds.
Using your own temperature probe test at the same point to
see if the sensor is reading accurately.
Now run a hot tap:
The temperature coming out of the top of the tank and the
temperature coming out of the tap and shower should be the
same. if not check for mixers, no insulation or plumbing
problems

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Legionella protection
Legionella
The legionella function operates the immersion heater in the hot water cylinder once a week
or every day to disinfect the hot water tank.
We normally encourage engineers to set the legionella function to start at 3 am on Tuesday
morning and to heat the tank to 60C for 10 mins. This is adjustable in the field settings
How it works
When the legionella timer (in the unit) starts the immersion heater is
used to heat the cylinder, the heat pump stops operating. Note the
legionella symbol shows but there is no pump symbol.
Legionella can be adjusted in the field settings:
Setting 3041 turns legionella on and off, NEVER turn it off
Setting 3042 tells us the day legionella will happen; you can choose
any day or every day.
Setting 3043 is the time legionella will start
Setting 3044 is the temperature the unit wants to see in legionella mode set it to 60C
Setting 3045 Duration is how long the heater continues to operate once the temperature in
3044 is met.
When it goes wrong
Legionella function only ends when the tank reaches the legionella set point.
If the immersion heater trips or is switched off the unit will gets locked in Legionella function. It
won’t heat the house or the hot water cylinder.
How can I get the unit to heat if it is stuck in legionella?
To restart the heating, you must switch off and on the hot water function press top right button
2 times.
Checking the immersion heater
To test the immersion heater, use the test mode on page 2
To access service mode press blue set button and test
button together for 6 seconds. The controller will display
TEST.
Press weekly to test the immersion heater in the hot water
cylinder
Test the current of the heater using an Amp clamp; this
measures the total amount of current. It is important to only
measure the current in 1 wire at a time. It should pull 13 Amps
The Gledhill tank has an immersion heater with its own stat;
this MUST be set 10 degrees above the legionella set point.
There is a cut out (black button) in the centre of the immersion
heater this must be pushed in to operate.

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The Operation of the HW cylinder
The operation of the HW cylinder is as follows:
Factory set, if the hot water set temperature is set to + 48C the unit will start heating the
cylinder when the temperature drops 5C below set point (43C), it will heat the cylinder until 2
degrees above set point or 50C.
The dead band can be adjusted using settings 3022 (2) to adjust how far over the set point it
heats too and 3023 (5) how many degrees the tank temp has to fall before hot water mode
starts.
There is a minimum operating time in HW mode of 5 mins, this can be adjusted in setting
3024. If the HW is switch on and then off again it will operate for this minimum period in HW.
The maximum operating time in HW mode is adjusted using setting 3025. For example, if HW
mode starts and setting 3025 is set to 30 minutes, the hot water mode will end IF either the 30
mins is reached or the set point is reached, whichever happens first.
Normally we set the max time to 60 mins for a 300L cylinder. But beware if we are heating the
cylinder we can’t heat the house at the same time.
If the cylinder has completed a HW cycle if cannot return to HW mode for a preset time
period, it’s measured in ½ hour segments,
and set in 3026. The factory setting is 3 = 90
mins. So the operation is like this:
Tank drops to 43C, HW mode starts, tank
temperature raises but after 30 mins it has
not reached set point, HW ends and heating
resumes. The tank is still not warm enough
but the unit will heat the house for 90 mins
then return to the tank for 30 mins and so
on.
None of the timers are used if there is no Heating demand, in this case the unit can heat the
tank 24 hours a day.

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Warm rads in summer
After HW mode is finished the compressor stops and the HW valve close, the heating valve
opens (there is always one valve open) this means any hot water left in the pipework will be
pumped around the heating circuit for the 6-minute run on. Some end users experience a rise
in radiator temp during this period. It’s just the unit getting rid of the excess heat in the water.
The operation of the immersion heater in the Cylinder:
The immersion heater in the cylinder is used primarily for legionella function. However, it has
a second operation helping with the hot water mode.
If you set the hot water set point above 48C the heat pump cannot achieve the set
temperature, it will always need help from the immersion heater. We advise 48C is the
maximum anyone uses for hot water mode. An average bath is run at less than 41C.
The immersion heater in the cylinder can be controlled in 3 ways:
Using the std/eco/pwr button (2nd from top right) the mode is changed.
When in eco mode 1 dot shows by the tap on the display, in this mode only the heat pump
heats the water, the immersion is never used.
When in std mode 2 dots show by the tap on the display, in this mode the heat pump heats
the water for a preset time adjusted in field setting 3032, if the cylinder is not up to set point
after this time the immersion heater starts up to help the heat pump.
When in pwr mode 3 dots show by the tap on the display, in this mode the heat pump and the
immersion heater run together all the time the unit is operating in HW mode.
We recommend std mode is used in all cases, its designed to help the unit get out of HW
mode quickly and return to heating the house. We usually set 20 min delay in 3032 for a 200L
cylinder or 60 mins for a 300L cylinder. The longer the delay the cheaper the system is to run
but the longer it takes to heat the water.

www.freedomhp.co.uk ©G Hendra Nov 18 12
If you are experiencing high run costs check the following:
It’s always assumed that the whole electricity bill is the heat pump, but this is not the case,
what is the background usage (lights TV, internet hot tub etc.?) this could be anywhere from 0
to 100% of this bill.
We need this figure to tell us what’s going on and so we can deduct this from the bill to work
out the heat pump run cost. It’s always a good idea when doing this work to take an energy
meter with you, kill the power to the heat pump and measure the background use when you
are there it really helps. You need to bear in mind you should expect heating bills of over
£100 a month in winter and nothing in summer but if you run the unit or any heating system in
the summer expect super high bills
Heating
It’s probable that the heat pumps are not set up right causing hi run costs, problems include
The stats are calling for heating all year long. (surprisingly common)
The stats are not connected to the heat pump, either wiring errors field setting 2091 not set
to1, etc.
There are towel rads keeping the unit running all year long.
Does the unit stop when you turn all your thermostats off?
With AU on the screen the unit should only heat is a run signal is sent into terminals B22 or
B24 on the unit. Switch off the thermostats and carry out the tests on page 2
Hot water
The tank stat is too low in the cylinder so the immersion is on all the time
The tank stat is not fully in the cylinder, if its pulled out it can’t see the tank temperature.
There is a recirc pump dragging the tank down all the time bringing in the immersion.
Is the tank temperature measured by the unit accurate, test this by measuring the
temperature of the water coming out of the cylinder and compare it with the measured
temperature using the view button on the controller? If the tank temperature sensor is reading
low the immersion will run constantly.
See video here http://www.youtube.com/watch?v=WbwDZ5vU4GM
Check that field setting 3032 is set correctly. This is the delay before the immersion comes in.
We usually set 20 min delay in 3032 for a 200L cylinder or 60 mins for a 300L cylinder.
Check the hot water set temperature is NOT above 48C, press the oval Set button and adjust
with + or - button

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Tank timers and solar
When using solar thermal it’s a good idea to time clock the cylinder so it’s off all day allowing
the solar to work.
Set an on time:
Press daily button once, no 1 and on shows, press set (grey), press up or down until the tap
symbol shows at the top of the screen with 2 dots, press set, adjust hours with up or down
button to 3 am, press set, minutes flash, press set. Now everything flashes press set (grey).
No2 appears ----
Now set an off time
With 2 showing press set (grey), press up or down until the tap symbol shows at the top of the
screen with 2 dots, press set, adjust hours with up or down button to 6 am, press set, minutes
flash, press set. Now everything flashes press set (grey). No3 appears
After everything is set no 3 will show. Press cancel delete twice; the normal screen will show.
Daily will appear next to the time. The timer is active
To delete a timer
To delete the timers, press daily repeatedly to scroll through all the set timers, when the one
you want to delete shows up, press and hold cancel delete for 5 seconds, keep doing this
until no1 shows, press cancel delete 2 x and in the normal screen daily will have disappeared.

www.freedomhp.co.uk ©G Hendra Nov 18 14
Weather Comp
In almost all cases we run our systems using an external run signal, be it a stat, switch, timer
or signal from an under floor heating manifold, these are connected to the control box as per
the diagram below.
By using these terminals, the water flow temperature is weather compensated, meaning flow
temperature varies with the ambient air temperature. You cannot control the flow temperature
yourself. The theory being as it gets colder outside the radiators get warmer and as it gets
warmer the radiators cool off. This function is used in all cases as it saves between 10 and 25
% on run cost across the year.
This is how it works: you set up the two curves (you can just use one) in the field settings as
per the diagram above. You must activate the stats using setting 2091 to activate terminal 22
and 2092 to activate terminal 24
When you make the connection 20-22 on
the control box the unit uses the blue
curve and lets water flow into the system,
valve 1 connected to 11 and 14 will be
open.
When you make connection 20-24 the
red curve (higher temp) is used and the
valve connected to 15 and 18 will be
open.
If both 20-22 and 20-24 are made the
unit runs at the higher of the two
temperatures both valves will be open.
On the screen of the unit you will see no
temperature setting, 0.0C shows. You
can boost the weather comp curve up or
down 5C using the up and down buttons
If you ask us we can give you a controller
which allows one of the curves to be flat
giving up to 50C flow in all ambient, this is useful for pools and as a boost function.

www.freedomhp.co.uk ©G Hendra Nov 18 15
Cold Weather Protection
The Samsung unit has a number of cold weather protection functions these include:
The heat pump cannot operate if the water in the system is less than 10C, if the unit detects
the heat exchanger is less than 10C it does two things:
Firstly, the pump is switched on for a couple of minutes to bring water in from the system
indoors to maintain the temperature. If the water coming in is also cold the unit will start the
heating function and will warm the water to 20C despite there being no run signal.
If the ambient temperature is less than -2C the water pump never stops, this is to prevent
freeze up.
Press the blue view button you can see 4 sensor readings, press it until the pump symbol
shows (a circle round a house). This is the water temperature, if it’s below 10C the unit will
not start but the pump will run.
If you are commissioning the unit from cold
You must warm up the water to get the unit to run, the easiest way to do this is to add a
cylinder and use the immersion to warm up the cylinder first, the warm water from the cylinder
will preheat the heat pump and it will start to operate. For more info see test mode.
Further cold weather cautions
If the remote controller gets cold (less than
5C) the unit will not operate correctly, it can’t
understand how the house has got so cold.
It will enter into a protection mode where it
runs constantly, you will find the on off button
for heating won’t work and if you try to use
HW mode it will switch itself off. Make sure
the remote controller is in a heated room.

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Testing the noise of the unit
Working out if a unit is noisy can be tricky because all testing is effected by the noise around
the unit.
We have tested a brand new unit here in our
warehouse in the following conditions.
Background noise 46dB (unit not running)
No obstruction within 1.5m of the front of the unit
Front cover removed
All measurements taken 300mm from the service
valves with S3 sound meter. Note these readings do
not relate to the figures given in proper sound testing
carried out by Samsung in Anechoic chambers with
covers on at 1m. The figures should be used for
reference purposes only.
Note how the unit is noisier as it starts and then settles
into a fairly steady increase in dB as it speeds up.
50
52
54
56
58
60
62
64
66
68
70
0 10 20 30 40 50 60 70
noise dB
Compressor speed Hz
Sound level RC09 & 16
dB Measured
RC090MHXEA
dB measured
RC160MHXEA

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Fault codes a guide
E121 or remote controller won’t initialise
On the back of the controller you can see 8 dip switches; these are used to programme the
unit. From factory all of them are switched off.
We use switch 1 to on to disable cooling mode
We use switch 2 to activate the sensor in the remote controller, this can (but don’t) be used to
control the unit using the Samsung controller as a room stat. In this mode the unit runs in
weather comp. both as a function of outdoor temperature (see weather comp) and as it gets
close to the set temperature the unit also drops the flow temperature.
Switch 3 if set to 1 brings up a fault code E121.
If switch 4 is set to 1 the controller will not start up properly. All that will be seen is some
flashing lines going in a circle under schedule.

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E101, E102, E201 and E202
E101 shows on the indoor unit if the outdoor unit has been off for more than 5 minutes
E201 and E102 is a communication error between indoor control box and the outdoor unit.
E202 shows on the outdoor unit if the indoor unit has been off for more than 5 minutes
The communication is carried out using the F1 and F2 cable between the two units.
Communication errors the most common cause of incorrectly diagnosing faults with PCBs.
The hardest thing for an engineer to do is work out which end has the communication error.
In the middle of the control box (indoor unit)
PCB there are two leds, the red one shows the
communication leaving the control box, the
orange / green led shows the communication
coming back from the outdoor unit. If there is a
comms error E201 one or both of the leds will
not be lit indicating which PCB is at fault.
NOTE if you kill the power to the indoor unit for
3 mins but leave the outdoor unit powered.
Now power up the indoor unit, note how if you
ask it for the flow temperature it shows -50C
this is because the indoor can’t see the flow
sensor which is in the outdoor unit. Note also
that the unit thinks its 0C outside; again the indoor unit can’t see the outdoor sensor.
After about 5 mins everything will sort itself out. In the mean
time you will see E201 error on the indoor remote and E202 on
the outdoor unit display
E201 also indicates issues with the outdoor unit, it’s worth
looking at the display in the outdoor unit to see if another fault
code is showing, this will indicate the fault in more detail.
The comms is a series of pulses. The outdoor unit
communicates with the positive part of the ac sine wave and the
indoor unit with the negative part; we measure the signal using
the DC range on our meters so we can see half of the
communication at one time to identify faults. See below.
Advanced tip:
With a min max multi meter you
can test both pcbs at once, set
the meter to DC Volts, set min
max running hold red lead on F1
and Black lead on F2. After 10
seconds check the max and min
Voltages, if there is a negative
reading the indoor board is
good, if there is a positive
reading the outdoor is ok.

www.freedomhp.co.uk ©G Hendra Nov 18 19
Electrically testing the communications
With unit completely powered up but NOT
running
Set your multimeter to DC Voltage, and place
the probes on F1 and F2 on the indoor mim
PCB, If the voltage reading is fluctuating
between 160mV and 210mV the units are
communicating healthily and there is no
problem.
If the Voltage is 0V, you must remove the red
plug from the main PCB in the outdoor unit
and check the voltage across the pins on the
board. If the Voltage across the pins is
between 270mV and 300mV and fluctuating,
the outdoor PCB is fine and you need to look
at the cables between the indoor and outdoor
PBC’s.
There is a terminal block on the outdoor unit,
below the PCB, labelled F1 and F2, this is
where the communication cables between the
two units are wired into, if the voltage reading
across F1 and F2 here is between 270mV
and 300mV, the Red plug and Blue/red wired
are fine and you’ll need to check for a break
or short in the cables that run between indoor
and outdoor units.
If the voltage here is 0V, you’ll need to
replace the red plug/red and blue wires

www.freedomhp.co.uk ©G Hendra Nov 18 20
E177 emergency stop
The mim control box pcb is faulty.
E203
E203 is caused by the inverter board not being connected
to the main PCB in the outdoor unit. The fault will be
displayed on the outdoor unit, the compressor will not run.
To fix the error TURN OFF THE POWER and wait 2 mins
before touching anything. Check the comms cable to the
inverter board, it is a grey cable with 6 cores, it goes from
the right hand side of the main pcb to the top left of the
inverter pcb, the inverter pcb is shown here. If one or
other of the plugs is not connected, plug it in and that
should clear the fault.
When operating correctly the inverter PCB
should have 3 leds showing, the red one at the
front will be on, the green one below it will be
flashing and a green led in the middle of the
board will be lit. If not the PCB is faulty.
When the comms is faulty or the pcb is broken,
the red led at the front will be on, the green one
below it will NOT be flashing and a green led in
the middle of the board will be lit. if this is the
case the pcb (inverter) is faulty.
The inverter pcb can fail due to either the fan motors or the compressors being faulty.
If the fan motor (or motors) or the compressor is faulty they can burn out the inverter
pcb.
You should test the components individually before connecting them to the new
inverter PBC.
See tests:
E467 for compressors
E475 for fan motors
E464 if you want to test the inverter and replacing the board