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.