Bosch DOMESTIC HOT WATER HEAT PUMP User manual

DOMESTIC HOT WATER HEAT PUMP
This document is confidential and restricted to exclusive use by the official technical
assistance of Bosch in the countries of destination of this product.
TECHNICAL MANUAL FOR AFTER SALES AND
SERVICE TECHNICIANS

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1.INTRODUCTION............................................................................................ 3
1.1 GENERAL DESCRIPTION ............................................................................................................ 4
1.2 PRODUCT PRESENTATION ......................................................................................................... 5
1.3 WORKING PRINCIPLE ................................................................................................................ 6
2.HEAT PUMP ELEMENTS .............................................................................. 7
2.1 ANODE PROTECTION................................................................................................................ 8
2.2 ELECTRICAL RESISTANCE AND THERMOSTAT........................................................................... 10
2.3 COIL FOR EXTERNAL SOURCE OF ENERGY ................................................................................ 12
3.MODULE ...................................................................................................... 12
3.1 COMPONENTS AND CHECKS IN THE REFRIGERATION UNIT......................................................... 13
3.2 COMPONENTS SYSTEM........................................................................................................... 14
3.3 MAIN COMPONENTS DATA...................................................................................................... 17
3.4 ELECTRICAL MEASUREMENTS................................................................................................. 19
4.COMPONENTS OVERVIEW........................................................................ 23
4.1 COMPRESSOR........................................................................................................................ 23
4.2 FILTERS AND DRIERS.............................................................................................................. 27
4.3 EXPANSION VALVE ................................................................................................................. 27
4.4 PRESSURE CONTROL BY NORMALLY CLOSED PRESSURE SWITCH ............................................... 28
4.5 EVAPORATOR ........................................................................................................................ 29
4.6 CONDENSER.......................................................................................................................... 30
5.HUMAN MACHINE INTERFACE – HMI....................................................... 31
6.MAINTENANCE AND PREVENTIVE ACTIONS .......................................... 37
6.1 CORROSION........................................................................................................................... 37
6.2 WATER QUALITY .................................................................................................................... 37
6.3 TYPES OF SCALE.................................................................................................................... 39
6.4 MAINTENANCE ACTIVITIES FOR TECHNICIANS............................................................................ 40
7.TROUBLESHOOTING.................................................................................. 47
7.1 FAILURES PREVENTION AND DETECTION................................................................................... 50
7.2 EVAPORATOR UNDER PERFORMANCE ...................................................................................... 51
7.3 CONDENSER UNDER PERFORMANCE ........................................................................................ 52
7.4 OTHER RECOMMENDATIONS AND DEFINITIONS .......................................................................... 53
7.5 SERVICE NEEDS..................................................................................................................... 54
7.6 TERMINOLOGY ....................................................................................................................... 55
8.APPENDIX.................................................................................................... 59

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1. Introduction
Domestic Hot Water Heat Pumps (DHW-HP), with or without air connections ducts, use the heat existing in the
surrounding air, or the waste heat from the indoor air, as energy source for DHW preparation.
These machines are commonly known as air-source hot water heat pump and they are energy-saving and
environmentally friendly equipment with a plug-and-play system structure and easy maintenance.
The heat pump has generally three operation modes:
-normal mode – only heat pump operation;
-combi mode– heat pump and electric resistance operation;
-electric heater mode– only electric resistance operation;
The heat source can be the waste heat as referred, but also the potential energy of unheated rooms, or the air
discharged from rooms with high humidity such as bathrooms, toilets and laundry rooms.
TTNR Brand Temp. Coil Commercial product name Product designation Market
7736500782 Bosch +5º/+35º Yes Compress 3000 DWFI HP 270-1E 1 FIV/S FR, GR
7736500891 Bosch +5º/+35º No Compress 3000 DWFI HP 270-1E 0 FIV/S FR
7736500989 Bosch -10º/+35º Yes Compress 3000 DWFO HP 270-1E 1 FOV/S FR, DK, GR
7736500991 Bosch -10º/+35º No Compress 3000 DWFO HP 270-1E 0 FOV/S FR
7736500781 Buderus +5º/+35º Yes Logatherm WPT 270 I-S HP 270-1E 1 FIV/S DE, BE, PL,
CZ, AT
7736500890 Buderus +5º/+35º No Logatherm WPT 270 I HP 270-1E 0 FIV/S DE, BE, PL,
AT
7736501013 Buderus -10º/+35º Yes Logatherm WPT 270 A-S HP 270-1E 1 FOV/S DE, BE, PL,
CZ, IT, AT
7736501014 Buderus -10º/+35º No Logatherm WPT 270 A HP 270-1E 0 FOV/S DE, BE, IT,
PL, AT
7736500884 elm leblanc +5º/+35º Yes Ondea PAC 270 AI-S HP 270-1E 1 FIV/S FR
7736500885 elm leblanc +5º/+35º No Ondea PAC 270 AI HP 270-1E 0 FIV/S FR
7736501015 elm leblanc -10º/+35º Yes Ondea PAC 270 AE-S HP 270-1E 1 FOV/S FR
7736501016 elm leblanc -10º/+35º No Ondea PAC 270 AE HP 270-1E 0 FOV/S FR
7736500169 Junkers +5º/+35º Yes SupraECO W SWI 270-1X HP 270-1E 1 FIV/S
DE, BE, PL,
CZ; ES, PT,
AT
7736500883 Junkers +5º/+35º No SupraECO W SWI 270-1 HP 270-1E 0 FIV/S DE, BE, PL,
ES, PT, AT
7736500988 Junkers -10º/+35º Yes SupraECO W SWO 270-1X HP 270-1E 1 FOV/S DE, BE, PL,
IT, CZ, AT
7736500990 Junkers -10º/+35º No SupraECO W SWO 270-1 HP 270-1E 0 FOV/S DE, BE, IT,
PL, AT
7736501149 Vulcano +5º/+35º Yes AquaEco HP270-1 E S HP 270-1E 1 FIV/S PT
7736501236 Vulcano +5º/+35º No AquaEco HP270-1 E C HP 270-1E 0 FIV/S PT
Table 1: Appliances overview

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1.1 General description
This model of domestic hot water heat pump provides hot water for residential purposes, using a closed refrigerant
unit filled with a refrigerant gas (R134a). This ensures the energy production taking out the energy from a cold
source - air, and delivering this energy to a secondary circuit – water - where a simple circulation pump, ensures
water movement through a heat exchanger, heating the water stored in a tank.
(a) (b)
Pict.1 (a) Refrigeration Unit and (b) Storage Tank (with coil)
The engine absorbs energy “Qc” from a cold source (heat absorbed from air) and expels energy “Qh” to a hot
destination (heat delivered to water) while Work “W” is done in the refrigerator circuit (electrical supply). The work
done is ensured by an electrical plug that supplies electricity to the compressor and the movement of the refrigerant
gas R134a ensures the transport of the energy from “Qc” to “Qh”.
Pict.2 – Heat Pump close circuit representation
Compressor
(W)
Heat sink
(Qh)
Condenser
Evaporator
Heat source
(Qc)
Expansion
Valve
Flow
direction

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1.2 Product presentation
Apart of the main function of the heat pump operation with the required mandatory components of an air/water heat
pump with electrical backup installed for any eventual need, the heat pump has, in some of the models, an internal
integrated coil for external energy source as integration with existent standing or wall hung boiler or even solar
energy installation.
Picture 3 shows the internal constitution and main components:
1) Fan and evaporator group
2) Compressor
3) Condenser (Plate Heat Exchanger)
4) Filter dryer and expansion valve
5) Water circulation pump
6) Storage tank
7) Electrical resistance for backup
8) Internal coil for external backup (eg. solar)
Pict.3 – Main Elements of the Heat Pump (model +5ºC / +35ºC)
1
2 4
3
5
6
7
8

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1.3 Working principle
The heat pump working principle is based on the transfer of the heat, and not on conversion of electrical energy
into heat. It removes energy from a low temperature source (ambient air) and transfers it into a high temperature
source (hot water tank).
Pict.4 – Energy and electrical input
Electricity is used to upgrade the comfort (temperature) of heat energy and not to generate heat energy. That is the
reason why COP (Coefficient Of Performance) of the heat pump is higher than 3 (which corresponds to an
efficiency of 300 %).
Pict. 5 – Generic overview of the 4 stages of gas
1. Liquid refrigerant R 134a boils at a low temperature in the evaporator. The output is a low temperature and low
pressure vapour.
2. Vapour pressure and temperature increase in the compressor. The electric motor is used to drive vapour
through the compressor and increase vapour temperature and pressure.
3. Heat exchange is done in the condenser. The refrigerant transfers heat to the water and cools up, condensing
and leaving energy there.
4. The liquid returns to the evaporator after passing through an expansion valve. The refrigerant pressure
decreases and the liquid evaporate again.
1
2
3
4

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2. Heat Pump Elements
The top EPP cover must be carefully disassembled before any intervention on the module. Follow instructions from
picture 6, existent in the sticker on the back of the tank.
Pict.6 – Disassembling of top cover
In front of the appliance and protected by an EPP front panel (fixed to the tank with 4 magnets), it is possible to find
the magnesium anode and the electric resistance for backup.
Pict.7 – Front view of the heat pump

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2.1 Anode Protection
The anode, installed in the water heater tank, will slowly dissipate whilst protecting it. The life of the water heater
tank is ensured by the periodical inspection, done by an authorised person, replacing it when required.
The anode inspection period shall take in consideration that, for softened water supply or in areas of worse water
quality, it is recommended to inspect it more often and for some other critical different situations, a water treatment
is recommended.
The DIN 4753 determines that all magnesium anodes must be checked, at least each two years (considering
normal conditions), ensuring a visual control.
The acceptable water quality to the heat pump storage tank requires:
-Water pH between 6,5 and 9,5
-Hardness range ≥3.0 ºdH.
Depending on the appliance production date, the anodes can have a measured terminal, or not. Those which do
not have a measurements terminal need a direct visual inspection to ensure its efficient operation and consequent
life time of the tank. Anodes with measurement terminal must be connected to the HMI in order to ensure correct
operation.
(a) Anode without terminal (non isolated) (b) Anode with terminal (isolated)
Pict.8 – Magnesium anode and measurement connections
Pict.9 – Magnesium anode with measurement terminal

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An anodic current meter can be used to measure the current and evaluate the anode time life. The measured value
shall be higher than 0,3 mA.
Attention: For a correct measurement, the tank must be full with water! The electrical connection must be ensured
after measurement.
Pict.10 – Anodic current measurement with an anode tester or a multimeter
Anyway, a visual inspection is strongly recommended every 2 year, in order to identify an eventual start of a crack
in a part of the anode, or eventually the calc deposition over the magnesium anode surface which will decrease the
anodic current as well, but will also disable the protection function of the anode.
The visual inspection should include a material surface, weight, diameter and length changing control.
Pict.11 – Example of used magnesium anodes

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2.2 Electrical Resistance and Thermostat
A thermostat control activates the electric resistance of 2kW immerged in the storage tank. This component has a
safety function set at 90ºC, limiting the temperature from an external source (solar, boiler, etc, …) to 80ºC.
Pict.12 – Electric Resistance (2 kW)
Pict.13 – Bipolar thermostat interfaces
Pict.14 – Check voltage supply o the thermostat
Temperature
adjustment

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Pict.15 – Check continuity between terminals
After any intervention in the anode and/or thermostat, ensure the correct assembly with correspondent washer and
assembly of the protection cover.
Pict.16 – Protection cover of the thermostat and electrical backup group
In the most recent production models, order to increase robustness of the tank in the models with coil, the electric
heater of the models HP 270-1E 1 (with coil), is from was isolated. Spare part will is available as isolated electric
heater for models, with and without coil.
a. Resistor (560Ω) b. Dielectric insulation (tank / electric heater)
Picture 17 – Isolated electric heater
Attention: Resistor connection Picture 17.a is essential to ensure function and life time of the electric heater and,
consequently, of the product. In case of defected component, the complete electric heater must be replaced.
a a
b b

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2.3 Coil for external source of energy
The coil integrated in the storage tank of some of the models (see table 1), can be used to combine the heat pump
with a back up energy system like solar, boiler, etc. In case the coil will not be used, do not remove the caps from
the coil inlet and outlet connections. This will avoid thermal losses due to the contact of the air in the coil with the
surrounding hot water in the tank.
In order to control the temperature in the tank for the external heat source, a pocket for external sensor is available
and adapted to the available fixation systems of sensors in TT, ensuring the correct contact with the tank.
Pict.18 – Storage tank and example of external sensor fixation system to pocket
3. Module
A routine maintenance agreement should be taken with a licensed service person or organisation. In addition, end-
users should monitor their installation and call a service person immediately, in case any abnormal
operation/situation is found. The system should be serviced by a qualified person, every 12 months, depending on
use/installation conditions.
Pict.19 – Components overview
Bosch / Buderus / Vulcano
Junkers / ELM Leblanc

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Components checking procedure
Unit
oInspect all the elements in the installation place
oCheck the airflow clearances
oCheck the output temperature
oClean the evaporator coils as following:
– Clear the outside of the coil of debris
– Vacuum the coil fins using a soft bristle brush attachment – take care to avoid bending the fins
– Spray water from the inside to the outside of the coils to remove stuck debris using a hose and spray gun
– Vacuum or remove by hand any remaining debris in the unit
oCheck if coil fins are damage – if bent, straighten them using a proper tool
oLubricate fan bearings if required – sealed bearing units do not require any oiling
oInspect fan and repair, if required
oEnsure that the condenser unit is secure and levelled in both directions. If necessary, adjust the levelling
feet on the appliance, or make level with timber/plastic shims. If the unit is seriously out of level, repair or
replace the base of the unit.
Refrigerant
oCheck the operation of the air-on/air-off with a digital thermometer
oCheck pipe joints for refrigerant leakage, with a bubble solution
Electrical
oCheck terminals and connections – clean and tight if necessary
oCheck the voltage and current
Service checklist
oProvide the end-user with a filled service checklist after each service
oExplain the importance of the thermal disinfection function (anti-legionella protection) for the water quality
inside the tank
3.1 Components and Checks in the Refrigeration Unit
The science of refrigeration is based on the fact that the liquid can be vaporized at any desired temperature by
changing its pressure. Taking in consideration the example of water, that under a normal atmospheric pressure of
1,01 bar boils at 100ºC, if in a closed vessel under a higher pressure, it boils at a higher temperature.
ATTENTION
The technician for the refrigeration circuit must have specific material and tools to deal with these circuits and make
the measurements and controls in the correct way, respecting the existing standards.

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The list of available material (separate document) must be checked in order to choose the adequate material for
repairs in the refrigeration circuit.
3.2 Components System
Model + 5ºC to +35ºC
The refrigerant must enter in the evaporator, in the liquid state, and then, by vaporizing due to heat absorption from
the surrounded air, the refrigerant leaves the evaporator in the vapour state and during the refrigerant
condensation, there is a heat generation, which will be transferred, in this case, to the domestic water, that flows in
the condenser.
Pict.20 – General components overview in the module +5ºC / + 35ºC
As the temperature of the available water is always higher than the one from boiling refrigerant in the evaporator,
the refrigerant in the vapour state needs to be pressurized till its condensing temperature is above the temperature
of the water available for the condensing process – that is why a compressor is needed.

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The compressor and condenser are needed to enable the same refrigerant to be used several times. The cost of
compressing and condensing the vaporized refrigerant is far less than the cost of often renewing of the refrigerant.
To maintain the difference in pressure between the condenser and the evaporator caused by the compressor, an
expansion valve is needed. The expansion valve separates the high pressure from the low pressure side in the
system. Only a small amount of refrigerant liquid flows through the valve. In fact, the valve is adjusted so that the
liquid flow rate is the same as the evaporation rate.
The refrigerant boils in the evaporator at a constant low pressure and temperature. Heat is removed from the air,
cooling it. After leaving the evaporator, the vaporized refrigerant flows through the compressor, where the pressure
of the vaporized refrigerant is raised to a point at which it can be condensed by some relatively warm fluid (water at
normal conditions).
The compressor removes the refrigerant vapour and this creates such a low pressure in the evaporator that the
evaporation temperature is kept below the surrounding temperature. After being compressed, the vapour enters the
condenser and is condensed at constant pressure and temperature. Heat is transferred from the condensing
vapour through the walls of the condenser to the water in the tank.
The expansion valve has two functions: maintain the pressure difference between the condenser and the
evaporator, together with the compressor and regulate the volume of refrigerant going to the evaporator, in order to
ensure a correct evaporation and allow the absorption of energy by the gas.
Pict.21 – Schematic representation of heat pump principle
Heat exchange
(Air/R134)
Compressor
Heat exchange
(R134/Air)
Expansion

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Model - 10ºC to +35ºC
The working principle of this model is the same as for +5ºC to +35ºC, with exception of the defrosting process,
which is done through a solenoid valve, activated by the control unit, depending on the temperature measured by
the NTCs, assembled in the evaporator fins and sensing the air temperature which will be detailed further in this
manual.
Pict.22 – General components overview in the module -10ºC / + 35ºC

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3.3 Main Components Data
Evaporator
Suppliers: Behr, Mahle
Specification from supplier:
-Cooling capacity of 1.4 kW
Fan
Supplier: EBM PASPT
Specification from supplier:
-Centrifugal fan operation 230 V
Compressor
Suppliers:
Mitsubishi
(model KB 134 VFN),
Highly
(model WHP01900BSV)
Specification from supplier:
-2 kW of heating capacity
-Thermal protection included
(temperature limiter: opens at
160ºC, closes at 70ºC)
Condenser
Supplier: Swep
Specifications from supplier:
-Maximum pressure 50 bar
Pump
Supplier: Wilo ZRS12/2-3KV
Specifications from supplier:
-3 speed pump
-maximum pressure 10 bar
-IP44
-Q flow = 0.2 m3/h

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Dry filter
Supplier: Honeywell
(Series FF)
Specifications from supplier:
- Liquid line filter drier
- Drying agent in bulk
- Low pressure drop
- Hermetic construction
- Temperature range: TS = -40ºC / +80ºC
Expansion valve
Supplier: Honeywell
(Series TLK)
Note:
Capillary tube length of 1 m
MOP at +15ºC - TEV with built in orifice of 2
mm, bulb Ø of 12 mm, internal equalization
and fixed superheating setting.
Specifications from supplier:
- Thermostatic expansion valve for serial
produced systems.
- Max. ambient temperature: 100ºC
- Max. bulb temperature: 140ºC
- Evaporating temp.: - 15...+40ºC
- Inlet ODF: 3/8" / Outlet ODF: 1/2"
Pressure Switch
Supplier: Danfoss
Low Pressure Switch (LPS)
PS = 45 bar
TS = 30ºC – 85ºC
High Pressure Switch (HPS):
PS = 45 bar
TS = 30ºC – 85ºC
Table 1 – Module components overview

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3.4 Electrical Measurements
Pict.23 – Electrical diagram -10ºC / +35ºC
Position
(Scheme Nr)
Model
+5ºC / +35ºC
Model
-10ºC / +35ºC Component Characteristics
A5 / B1 X X Air NTC R 10k = 25ºC = 10000 Ω
A11 / B2 X X Hot Water NTC R 10k = 25ºC = 10000 Ω
A13 / B3 X X Cold Water NTC R 10k = 25ºC = 10000 Ω
A19 / B15 X Fins NTC R 8k = 25ºC = 8400 Ω
A12 / B10 X X Pump Wilo
230 (196 – 253) Vac
50 (47,5 – 52,5) Hz
19 / 32 / 48 W (0,10 / 0,15 / 0,21 A)
A4 X X Condenser “Swep” type
A14 X X Filter Drier PS = 11 – 43 bar
Scheme A Scheme B

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Position
(Scheme Nr)
Model
+5ºC / +35ºC
Model
-10ºC / +35ºC Component Characteristics
A15 X X Expansion valve TLK 2.0 R134a / MOP + 15ºC
A2 X X Evaporator 14 x 3 tubes
A20 / B16 X Solenoid Valve 230 V / 50 Hz
A1 / B11 X X Fan
230 (196 - 253) Vac
50 (47,5 - 52,7) Hz
85 W
A3 / B7 X X Compressor
230 (198 - 264) Vac
50 (47,5 - 52,5) Hz
520-565 W / 475-490W
(Mitsubishi / Highly)
B6 X X Compressor Capacitor 17 μF / 15 μF
(Mitsubishi / Highly)
B8 X X Compressor Protection
Bimetallic thermal switch
(open at 160ºC, close at 70ºC)
B4 X X
Supply Cable to control
unit 230 V (+10% / -15%), 50 Hz
B5 X X High Pressure Switch
Temp. = 60ºC
Opening pressure = 27 bar*
Closing pressure = 20 bar*
B9 X X Low Pressure Switch
Temp. = 5ºC
Opening pressure = 0,7 bar*
Closing pressure = 2,4 bar*
A10 / B12 X X Electric resistance 230 V / 50 Hz (R=26,5Ω)
A10 / B13 X X Safety Thermostat T sec = 90ºC
B14 X X Control Unit 230 V (+10% / -15%), 50 Hz
* Relative pressures
Table 2 – Schemes A and B - components identification