Bosch tw series water to water heat pump (24 pages)
Summary of Contents for Bosch DOMESTIC HOT WATER HEAT PUMP
TECHNICAL MANUAL FOR AFTER SALES AND SERVICE TECHNICIANS 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.
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 Compress 3000 DWFI HP 270-1E 1 FIV/S FR, GR 7736500891 Bosch +5º/+35º...
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 –...
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.
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).
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.
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.
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.
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 –...
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.
The system should be serviced by a qualified person, every 12 months, depending on use/installation conditions. Junkers / ELM Leblanc Bosch / Buderus / Vulcano Pict.19 – Components overview 6720649497 SM HP270-1 2012/09 en Page 12 from 63...
Components checking procedure Unit Inspect all the elements in the installation place Check the airflow clearances Check the output temperature Clean 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 –...
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.
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.
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.
3.3 Main Components Data Evaporator Suppliers: Behr, Mahle Specification from supplier: Cooling capacity of 1.4 kW Specification from supplier: Supplier: EBM PASPT Centrifugal fan operation 230 V Compressor Specification from supplier: 2 kW of heating capacity Suppliers: Thermal protection included Mitsubishi (temperature limiter: opens at (model KB 134 VFN),...
Specifications from supplier: - Liquid line filter drier Dry filter - Drying agent in bulk - Low pressure drop Supplier: Honeywell - Hermetic construction (Series FF) - Temperature range: TS = -40ºC / +80ºC MOP at +15ºC - TEV with built in orifice of 2 mm, bulb Ø...
The NTC’s listed in the table above, are supplied in a common cable with the following configuration: (A) model -10ºC / +35ºC (B) model +5ºC / +35ºC Pict.24 – NTC cables The NTC sensors for air, cold and hot water are the same, but give different information to the software in the electronic control.
2957 2986 2521 2488 2157 2083 1853 1752 1598 1481 1384 1258 1202 1072 1048 Table 3 – NTC characteristic Pict.25 – Electrical cables connection on HMI Electrical Supply connection Pump Connection Capacitor Connection Fan Connection Fan Capacitor Pict.26 – Cable connections overview 6720649497 SM HP270-1 2012/09 en Page 22 from 63...
Components Overview 4.1 Compressor The compressor is usually driven by an engine and this unit compresses or transports the refrigerant through the system. The main principle is that the refrigerant is compressed as it is sucked into the compressor in a gaseous form at a low temperature from the evaporator.
Electric test to the compressor: The compressor has some electrical connections and a temperature limiter thermostat that ensure its protection. Using a multimeter, is possible to control its functionality, nevertheless the HMI will detect if compressor is running. Cables and cover protection have clear identification of the different connections. R –...
Electric test to compressor: Check earth connection C – chassis ≠ 0 S – chassis ≠ 0 R – chassis ≠ 0 Attention: In case of continuity the compressor is defected Pict.30 – Testing of compressor Thermal Protection This function is ensured by a bimetallic temperature limiter which opens its contact when high temperature (T=160ºC ±10ºC) is reached during operation.
(a) Open contact (b) Close contact temperature activation – T≥160ºC normal operation – T<70ºC Pict.32 – Functional position After any intervention, ensure correct cover protection assembly. Pict.33 – Cover of electrical elements from compressor Capacitor of Compressor Pict.34 – Discharging capacitor In case of check capacitor, discharge electric charge with a resistance of 20k and 2W Not OK - ∞...
4.2 Filters and driers Moisture or water vapour may cause problems in any type of refrigerant system, because moisture may freeze in the orifice of the expansion valve, causing corrosion of metal parts and wet the motor of the compressor, damaging it (motor burnout and oil sludge).
evaporation cooling. In order to achieve optimum cooling capacity in the evaporator, the refrigerant flow is controlled by the expansion valve or orifice tube. The component achieves high durability thanks to welded stainless steel head and stainless steel diaphragm and contains the gas charge for quick response time adapted to small evaporators.
Pict.38 – Pressure switch from Danfoss Various shunt relays are triggered by the pressure switch in order to guarantee safe and effective use of the refrigerant system under all conditions. Through this process, individual system components are switched on and off according to the defined pressure points.
Pict.40 – Fan and Evaporator 4.6 Condenser Domestic Hot Water Side (Secondary circuit) Refrigeration side (Primary circuit) Pict.41 – Condenser The condenser is required to cool down the refrigerant heated up by compression in the compressor. The hot refrigerant gas flows into the compressor, thereby dissipating heat to the other side of the plate. As it cools, the refrigerant pressure falls and the refrigerant state changes from gaseous to liquid.
Pict.42 – Plate heat exchanger condenser working principle In case of hard water, the condenser shall be periodically cleaned in order to avoid obstruction. Pict.43 – Plates of the heat exchanger and counter-flow representation Human Machine Interface – HMI User manual must be used to verify functions and active parameters. For the service mode, following instructions should be considered.
Display (LCD) Selection Buttons Pict.44 – HMI Panel Entrance in the service mode: Press “Menu” + “Ok” button during more than 5 sec Pict.45 – Enter in service mode Table 4 includes the meaning of each parameter visible on the service mode that can be used by technicians for diagnostic and repair actions.
Number of air defrost procedures Number of gas defrost procedures last 10 failures with error code indication 1F until 10F Attention: (If no error is memorized, display shows “-- --“) cleaning of the historical memory of the last 10 failures test display (all segments ON) Exit Service Mode (for FD<202, minimum press time of 3sec)
The working principle is based in the following considerations: Switch OFF No Reaction from system Switch ON (main switch in the back of HP) Error in memory? Stand-by mode Error Mode For Stand-by Mode Stand-by mode HMI actuation LCD Backlight ON LCD Backlight OFF (after 15 sec without any selection) Active Operation Mode...
Conditions for operation: The heat pump compressor is activated according the following conditions and according control unit settings defined. ≤ T – 3ºC Start Up < 60ºC) bottom ≥ T Stop ≥ 62ºC) bottom Conditions for anti-freeze protection (in HP or Standby mode): Software version after HPAF0211 (-10ºC models) and HPAF0311 (+5ºC models): Module Anti-Freeze: <...
Full mode until T = 60ºC Electric Heater mode until T = 70ºC Legionela stops when: ≥70ºC or T ≥ 60ºC Bottom (or time in Legi > 24h) Conditions for air-defrost sequence: Air defrost sequence is activated in both +5ºC or -10ºC models when T >...
Maintenance and preventive actions 6.1 Corrosion Corrosion is the term for a chemical or electrochemical reaction between a material, usually a metal, and its environment, which produces a deterioration of the material and its properties. A metal can be exposed to many different kinds of corrosion and below we can see some examples of the ones applicable to this type of brazed plate heat exchangers.
The corrosive effect of natural water can vary considerably with its chemical composition. Water quality is of great importance to avoid corrosion in the plate heat exchanger (condenser). City Water Normally is controlled and of good quality. Well water Is usually fairly cold and clean, which implies that it has a low biological content. However, the concentration of scale forming salts (calcium and magnesium sulphates and carbonates) can sometimes be very high.
calcium content alkalinity ionic strength of the water (Is) Please note: For water analysis, mg/l is equivalent to ppm The relation between calcium and calcium carbonate is 40g CA ≃ 100g CaCO TDS = salt content (mg/l) or possibly the conductivity x 0.63 (μS/cm) If Is<0, the water has a tendency to be corrosive.
Check position*, connection, continuity Cables * Ensure distance to copper pipes Safety valve Manual activation Pre-charge verification (vessel without Expansion vessel water pressure) Pipe work Leakages, lack or defective insulation Cleaning of calc deposition, inspection of Heating element integrity Table 6 – Resume of main maintenance actions The main connections are through thread connection with washer, however and for the connections of the flexible hose with o’ring connection, the lubricant L 641 (part nr 8 709 918 413 - Water lubricant for water valve connections) must be used.
In the NTC sensor, in contact with the pipe of cold water from the bottom of the storage tank, and in the NTC sensor, in the pocket of the hot water from the top of the tank, the thermal paste “Wacker” (part nr 8 719 918 658) must be used to ensure an efficient contact and consequent efficient temperature sensing.
Pict.49 – Kaloxi descaling liquid to clean plate heat exchangers Descaling process: Close cold water inlet and open hot water tap to take out pressure from the top of the heat pump; Remove connection in the top of the condenser plate heat exchanger to allow the outlet of the water and then, remove the connection in the bottom;...
Pict.51 – Flexible hose of descaling pump connection - Put the pump in operation, taking in consideration that the flow must be, inside the heat exchanger, in the opposite direction of the water. The direction can be defined in the pump on the correspondent lever, as shown in picture 51.
Pict.53 – Example of a manual air purge Evaporator Maintenance The fins of the evaporator should be cleaned and aligned in order to allow an adequate air flow through the complete surface, ensuring the correct function of the evaporator, and the consequent energy transfer to the refrigerant gas.
Pict.56 – Example of cleaning and purifier spray for evaporators application For the maintenance, diagnostic and performance analysis of the heat pump module and its refrigerant circuit, following information must be taken in consideration. On chapter 7, additional information is described to help the understanding of the operation of the circuit.
Troubleshooting Code E01 Lock Out error Fault in the hot water NTC temperature sensor (in the top of the tank) Check connection to control unit and cable Sensor is disconnected integrity Sensor is in short circuit Check cable, sensor and measure NTC value NTC has values out of its borders Measure NTC sensor value Code E02 Lock Out Error...
Code E07 – Only for internal technical use Code E08 – Only for internal technical use Code E09 Lock Out Error Failure in Compressor System Condition: Appliance was turned on, is in standby and fault was displayed before operation Contacts Open on safety elements - thermal protection Check Continuity Contacts Open on safety elements –...
Contacts Open on safety elements – high pressure switch Check Continuity Contacts Open on safety elements – low pressure switch Check Continuity Fault in the low pressure side High pressure loss in the air ducts Check ducts and accessories equivalent length Failure in fan operation Check fan operation and connection Check with an leakage detector the origin of the...
7.1 Failures prevention and detection The design data supplied by Bosch must be known by authorized service partner’s technicians, in order to prevent and avoid the following problems, nevertheless, the service partner is responsible to prepare technicians in such a way that the following problems will never happen in the field with an end user.
7.2 Evaporator under performance The evaporation process is sensitive and potentially unstable. Minor changes in performance have major effect on the system performance (COP). A one-degree change in the evaporation temperature changes the COP by approximately 3% and an unstable process could also cause the evaporation temperature to fluctuate, with a potential risk of freezing in the evaporator.
If the filter located after condenser and before expansion valve is saturated and the pressure drop is too high, replace component. Check the discharge temperature Compare with design conditions supplied by Bosch. 6720649497 SM HP270-1 2012/09 en Page 52 from 63...
7.4 Other recommendations and definitions Pict.60 – General refrigeration circuit representation Pre-assessment for technical partners (refrigerant circuit) experience in training, installation, service, maintenance, commissioning, retrofitting, system design current experience in other refrigerant circuit appliances as air conditioning, other heat pumps types, chillers, …...
7.5 Service Needs Using pressure manometers and thermometer The normal measuring equipment is a service pressure gauge and preferably some type of thermometer. Data is collected using fixed gauges and connecting service gauge to the available connections to the service in the system.
During the process of repairs and manometer connections to the pressure gauges, check the eventual existence of micro-leakages with an adequate equipment in order to avoid the lost of refrigerant gas to the atmosphere and consequent malfunction in the appliance operation after your visit. Pict.63 –...
Efficiency Definition The basic compressor-driven refrigeration cycle consists of one compressor, two heat exchangers (evaporator and condenser) and a throttling device (expansion valve). These components form the circuit in which the refrigerant circulates and the cycle operates between the two pressure levels P1 and P2, and the temperatures T1 and T2, where T1 >...
In the ideal cooling circuit the superheat is 0°C. This means that the whole evaporator is being used for vaporization, and the efficiency is as high as possible We need a few degrees of superheat in order to establish the expansion valve operation and make sure that no liquid is brought inside the suction side of the compressor Attention: If liquid gets into the compression chamber of a piston compressor it will cause serious damage High superheat;...
Pict.66 – Expansion valve and bulb position Sub-cooling The sub cooling is the difference between the condensing temperature and the liquid line temperature. The condensing temperature is determined with a pressure gauge and the liquid line temperature is measured with a digital thermometer ...
8. Appendix Guide with list of material for service partners The following list is only a guideline with the main important elements to make repairs in the refrigeration circuits of Heat Pumps. The material should be adequate for the proper use of refrigerant gas. Depending on the type of machine, other tools can be needed and the list should be adapted to the available equipment in the countries.
Soldering equipment To soldering components in repairs in the refrigeration circuit. Thermal paste (protect heat transmission to surrenders) To avoid damages in the components near of the soldering points Nitrogen Kit 1) Nitrogen cylinder 2) Nitrogen pressure For circulation inside of refrigerant regulator circuit during brazing process 3) Nitrogen transfer hose...
Recovery Equipment 1) Recovery unit ‘oil less’ for commercial To use during phase out of the refrigeration gas to deliver to a recovery 2) Condenser and ventilator cylinder used in the field to 3) High and low pressure recover, recycling, reclamation gauges and evacuation of refrigeration 4) Refrigerant inlet and...
Brush / cleaning tools 1) steel brush Inner and outer cleaning and finishing works of soldering Cleaning / protection sprays sprays disinfection: pulverize in the evaporator fins, avoiding the deposition of bacteria’s in the air flow way spray to retire dirtiness, grass and other elements from fins aggressive aluminum.
To use in NTC sensors of contact type to improve conductivity Table 10 – List of material for safety, handling and repairs Bosch, Termotecnologia S.A TT-DW/STI – International training and technical support - Aveiro Plant 6720649497 SM HP270-1 2012/09 en Page 63 from 63...