Junkers miniMAXX WR 11-2 B Series Gas Heater Manual

W Water gas heater
R Proportional power adjustment
D Digital display
11 Capacity (l/min)
-2 Version 2
B Electronic ignition powered by 1.5 V batteries
23 Indicator number of natural gas H
31 Indicator number of LPG
S. Country code

Supplied materials

• Gas heater
• Attachment elements
• Connection elements
• Heater documentation
• Two 1.5 V batteries type R
• Rubber holders (LPG heaters).

Description of the heater

Operating convenience, as the heater is ready to operate by simply pressing a switch.

• Heater for wall-mounting
• Ignition by electronic device triggered when the water valve opens
• Gauge to display temperature, burner operation and malfunctions
• Temperature sensor to monitor the water temperature at the heater output
• Great savings in comparison with conventional heaters, due to the possibility of power adjustment and no permanent pilot flame
• Natural gas/LPG burner
• Semi-permanent pilot burner which only functions during the period between the opening of the water valve and the ignition of the main burner
• Heat exchanger without tin/lead covering
• Water automatic in fibreglass-reinforced polyamide, 100% recyclable
• Automatic adjustment of the water flow by means of a device which permits a constant flow to be maintained in spite of variable pressure supplies
• Gas flow adjustment proportional to the water flow to maintain a constant high temperature.
• Safety devices:
  • Ionisation probe to check for accidental extinction of the burner flame
  • Combustion gases monitoring device which turns off the heater in case of inadequate combusted gas evacuation conditions
  • Temperature limiter which prevents overheating of the heat exchanger

  Special accessories

  • Conversion kit from natural gas to butane/propane and vice-versa.

  Dimensions

  

  
  Fig. 1

  1. Heat exchanger
  2. Burner
  1. Temperature/volume selector
  1. Gas connection
  1. Ignition unit
  2. Battery compartment
  1. Power selector
  1. LED - Burner status check
  2. Switch / LED - Battery status check
  3. Front
  4. Opening for mounting on the wall
  5. Connection collar to the combustion gases pipe
  6. Flue with non-return device
  7. Gas automatic
  1. Digital display

  Dimensions (mm)	A	B	C	D	E	F	G	H (Ø)
  								Natural gas	LPG
  WRD11B	310	580	228	110	463	60	25	3/4"	1/2"
  WRD14B	350	655	228	130	510	95	30	3/4"	1/2"
  WRD18B	425	655	334	130	540	65	30	3/4"	1/2"

  Tab. 3 Dimensions

  Functional diagram of the heater

  

  
  Fig. 2 Functional Diagram

  1. Pilot burner
  2. Spark plug
  3. Ionisation probe
  4. Heat exchanger
  5. Main burner
  6. Injector

  7a Screw for measurement of pressure in burner
  7b Screw for measurement of input pressure

  1. Slow ignition valve
  2. Venturi
  3. Temperature/volume selector
  4. Water automatic
  5. Command cone
  6. Water flow regulator
  7. Water filter
  8. Micro-switch
  9. Cold water pipe
  10. Diaphragm
  11. Main gas valve
  12. Maximum gas adjusting screw
  13. Gas supply pipe
  14. Gas filter
  15. Hot water pipe
  16. Ignition unit
  17. Battery compartment
  18. Servo valve
  19. Power selector
  20. Gas valve
  21. Pilot valve
  22. Pilot injector
  23. Pilot gas pipe
  24. Temperature limiter
  25. Combustion gases monitoring device
  1. Temperature sensor

  Electrical diagram

  

  
  Fig. 3 Electrical diagram

  1. Spark plug
  2. Ionisation probe
  1. Micro-switch
  1. Ignition unit
  2. Battery compartment
  3. Servo valve (normally open)
  1. Pilot valve (normally closed)
  1. Temperature limiter
  2. Monitoring of combustion gases
  3. Diaphragm valve
  4. LED - Burner status check
  5. Switch / LED - Battery status check
  1. Temperature sensor
  2. Digital display

  Function

  This gas heater is equipped with automatic electronic ignition which simplifies its operation.

  • To do so, just turn on the switch (Fig. 9).

  After this procedure, automatic ignition occurs whenever a hot water tap is opened. First, the pilot burner is lit and approximately four seconds afterwards the main burner. The pilot burner flame is then extinguished after a short period of time.
  This is a way of saving a great amount of energy as the pilot burner only operates for the minimum necessary time to ignite the main burner, in contrast to conventional systems which operate permanently.

  Air in the gas supply pipe when the heater is started up may cause ignition to fail.

  If this happens:

  • Close and open the hot water tap to repeat the ignition process until all the air has been purged.

  Technical characteristics

  Technical characteristics	Symbol	Units	WRD11	WRD14	WRD18
  Power and flow
  Nominal useful power	Pn	kW	19,2	23,6	30,5
  Minimum useful power	Pmin	kW	7	7	9
  Useful power (adjustment range)	kW	7 - 19,2	7 - 23,6	7 - 30,5
  Nominal thermal flow	Qn	kW	21,8	27	34,5
  Minimum thermal flow	Qmin	kW	8,1	8,1	10,3
  Gas data*
  Supply pressure
  Natural gas H	G20	mbar	20	20	20
  LPG (butane/propane)	G30/G31	mbar	30/37	30/37	30/37
  Consumption
  Natural gas H	G20	m 3 /h	2,3	2,9	3,7
  LPG (butane/propane)	G30/G31	kg/h	1,7	2,2	2,75
  Number of injectors	12	14	18
  Water data
  Maximum permissible pressure**	pw	bar	12	12	12
  Temperature selector in fully clockwise position
  Temperature rise	°C	50	50	50
  Flow range	l/min	2 - 5,5	2 - 7	2 - 8,8
  Minimum operating pressure	pwmin	bar	0,1	0,1	0,2
  Minimum pressure for maximum flow	bar	0,25	0,35	0,5
  Temperature selector in fully anti-clockwise position
  Temperature rise	°C	25	25	25
  Flow range	l/min	4 - 11	4 - 14	4 - 17,6
  Minimum operating pressure	bar	0,2	0,2	0,2
  Minimum pressure for maximum flow	bar	0,6	1	1,3
  Combustion products***
  Minimum low pressure	mbar	0,015	0,015	0,015
  Flow	g/s	13	17	22
  Temperature	°C	160	170	180

  * Hi 15°C - 1013 mbar - dry: Natural gas 34.2 MJ/m3 (9.5 kWh/m3)
  LPG: Butane 45.72 MJ/kg (12.7 kWh/kg) - Propane 46.44 MJ/kg (12.9 kWh/kg)
  ** Considering the water dilution effect this value must not be exceeded.
  *** For nominal calorific power

  Regulations

  Any local by-laws and regulations pertaining to installation and use of gas-heated appliances must be observed. Please refer to the laws that should be attended in your country.

  Installation

  The gas installation, the connection of exhaust/supply pipes as well as the initial startup are to be performed exclusively by authorised gas fitters.

  The heater can only be used in the countries indicated on the rating plate.

  Important information

  • Before installing, call the gas company and check the standard relating to gas heaters and ventilation requirements for rooms.
  • Install a gas cut-off valve as close as possible to the heater.
  • After finishing the gas system, the pipes must be thoroughly cleaned and leak-tested; to avoid damaging the gas automatic by excess pressure, this test must be performed with the gas valve of the heater closed.
  • Check if the heater corresponds to the type of gas provided.
  • Check if the flow and pressure through the installed reducer are appropriate for the consumption of the heater (see technical data in the table 4).

  Selection of the place of installation

  Requirements regarding the place of installation

  • Do not install the heater in rooms with a volume of less than 8 m 3 (not including the volume of the furniture providing this does not exceed 2 m 3 .
  • Comply with the specific instructions for each country.
  • Assemble the gas heater in a well-ventilated location where it will not be exposed to temperatures below zero and in a place where there is an evacuation pipe for combustion gases.
  • The gas heater must not be installed over a heat source.
  • To avoid corrosion, the combustion air must be free from harmful substances. Examples of particularly corrosive substances: halogenated hydrocarbons contained in solvents, paints, glues, engine gases and various domestic detergents. If necessary, take adequate measures.
  • Respect the minimum installation clearances indicated in Fig. 4.
  • The heater must not be installed in locations where the room temperature can reach 0°C.

  In case of a frost risk:

  

  • Turn the heater off
  • Remove batteries
  • Purge the heater.
    
    Fig. 4 Minimum clearances

  Combustion gases

  • All gas heaters must be connected in a leak-roof manner to a gas evacuation pipe of adequate dimensions.
  • The flue must:
    • be vertical (reduced horizontal sections or no horizontal sections at all)
    • be thermally insulated
    • have an exit above the maximum roof level

    
    Ensure that the extremity of the evacuation pipe is placed between the ledge and the ring of the flue

    If these conditions cannot be met, a different location must be selected for the gas intake and evacuation.

    Surface temperature

    The maximum surface temperature of the heater is less than 85°C, with the exception of the combustion gases evacuation device. No special protection measures are required for flammable construction materials or built-in furniture items.

    Air intake

    The place where the heater is to be installed must have an area of air supply according to the table.

    Heater	Minimum useful area
    WRD11B	≥60 cm 2
    WRD14B	≥90 cm 2
    WRD18B	≥120 cm 2

    Tab. 5 Useful areas for air intake

    The minimum requirements are listed above; however, each country's specified requirements must also be respected.

    Heater mounting

    • Remove the temperature/flow selector and the power selector.
    • Unscrew the front fixing screws.
    • With a simultaneous movement towards you and upwards, release the front of the two lugs from the back.
    • Fix the heater vertically, using the provided screw hooks and plugs.

    
    Never support the gas heater on the water or gas connections.

    Water connection

    It is advisable to purge the installation beforehand, because the presence of dirt may reduce the flow and, in extreme cases, cause a blockage.

    

    • Identify the cold water pipe (Fig. 5, item A) and the hot water pipe (Fig. 5, item B), so as to avoid any possible mis-connection.
    • Connect the water pipes to the water automatic using the provided connection accessories.
      
      Fig. 5 Water connection

    It is advisable to install a non-return valve on the supply side of the heater to avoid problems caused by sudden changes in supply pressure.

    Gas connection

    Any local by-laws and regulations pertaining to installation and use of gas-heated appliances must be observed.
    Please refer to the laws that should be attended in your country.

    Startup

    • Open the water and gas flow valves and check that all connections are leak-tight.
    • Insert the two batteries correctly (Fig. 8) 1.5 V type R supplied with the heater.
    • Check the combustion gases monitoring device is functioning correctly, proceed as explained in " Combustion gas probe".

    Use

    Open all water and gas blocking devices. Purge the pipes.

    
    The front panel in the burner and pilot burner area may reach high temperatures, with risk of burning in case of contact.

    Digital display - description

    

    
    Fig. 6 Digital display

    1. Temperature/error code
    2. Malfunction indicator
    3. Temperature measurement units
    4. Heater in operation (burner turned on)

    Batteries

    Battery insertion

    

    • Insert the two 1.5 V R20 batteries.
      
      Fig. 7 Inserting the batteries

    Replacing the batteries

    

    The batteries must be changed if the red LED starts flashing.
    
    Fig. 8 Replacing the batteries

    Precautions when using the batteries

    • Do not insert flat batteries.
    • Only use the type of batteries indicated.

    Before starting up the heater

    • Initial startup must be performed by a qualified technician who will provide the client with all the necessary information for optimum operation of the gas heater.
    • Check if the gas indicated on the rating plate is the same as the one used at the location.
    • Open the gas valve.
    • Open the water valve.

    Turning the heater on and off

    Turning on

    • Press the switch , position .
      
      Fig. 9

    

    Green light on = Main burner on
    
    Fig. 10

    Turning off

    • Press the switch , position .

    Power adjustment

    Lower water temperature.
    Less power.
    
    Fig. 11
    Higher water temperature.
    More power.
    
    Fig. 12

    Temperature/flow adjustment

    

    • Turn anti-clockwise
      Increases flow and decreases water temperature.
      
      Fig. 13
    • Turn clockwise.
      Decreases flow and increases water temperature.

    Regulating the temperature to the minimum required value reduces energy consumption as well as the possibility of limescale deposits in the heat exchanger.

    
    The temperature on the display is not precise, always check before bathing children or elderly people.

    Adjustments

    Heater adjustment

    * Sealed elements must not be opened.

    Natural gas

    Heaters for natural gas (G 20) are supplied sealed from the factory after being adjusted to the values indicated on the rating plate.

    Heaters must not be turned on if the coni nection pressure is lower than 15 mbar or higher than 25 mbar.

    Liquefied gas

    Heaters for propane/butane (G31/G30) are supplied sealed from the factory after being adjusted to the values indicated on the rating plate.

    
    The following procedures must only be performed by a qualified technician.

    It is possible to adjust the power using the burner pressure process, although a manometer is necessary for this procedure.

    Pressure adjustment

    Accessing the adjusting screw

    • Remove the front part of the heater.

    Connecting the manometer

    

    • Unscrew the shut-off screws (Fig. 14).
    • Connect the manometer to the burner pressure measuring point.
      
      Fig. 14 Pressure measurement point

    Maximum gas flow adjustment

    

    • Remove the seal from the adjusting screw (Fig. 15).
    • Turn on the heater with the power selector set to the left (maximum position).
      
      Fig. 15 Maximum gas flow adjusting screw
    • Open various hot water taps.
    • Using the adjusting screw (Fig. 15), regulate the pressure until achieving the values indicated in the table 6.
    • Seal the adjusting screw once again.

    Minimum gas flow adjustment

    The minimum gas flow adjustment is performed automatically after the adjustment of the maximum gas flow.

    Natural gas H	Butane	Propane
    Injector code	WR11	8708202113 (1,10)	8708202130 (0,70)
    		8708202124 (1,20)	8708202128 (0,72)
    	WR14	8708202113 (1,10)	8708202128 (0,72)
    		8708202116 (1,25)	8708202132 (0,75)
    	WR18	8708202115 (1,15)	8708202130 (0,70)
    		8708202116 (1,25)	8708202132 (0,75)
    Connection pressure (mbar)	WR11 WR14 WR18	20	30	37
    MAX (mbar)	WR11	12,7	28	35
    	WR14	12	28	35
    	WR18	10,3	25,5	32,5

    Tab. 6 Burner pressure

    Conversion to a different type of gas

    Only use the original conversion kits.
    The conversion must only be performed by a qualified technician. The original conversion kits are supplied with assembly instructions.

    Maintenance

    Maintenance must only be performed by a qualified technician. After one or two years of use a general overhaul must be performed.

    
    Before performing any maintenance work:

    • Close the water flow valve.
    • Close the gas flow valve.
    • Only use original spare parts.
    • Order the spare parts according to the spare parts catalogue for the heater.
    • Replace the joints and removed O-rings with new ones.
    • Only the following lubricants must be used:
      • Hydraulic part: Unisilikon L 641 (8 709 918 413)
      • Coil unions: HFt 1 v 5 (8 709 918 010).

      Periodic maintenance work

      Functional check

      • Check the operation of all safety, adjustment and monitoring elements.

      Heat exchanger

      • Check the heat exchanger is clean.
      • In case of dirt:
        • Remove the heat exchanger and take out the limiter.
        • Clean the chamber with a powerful jet of water.

        Burner

        • Check the burner annually and clean it if necessary.
        • If it is very dirty (grease, soot): Remove the burner, soak it in hot water with detergent and clean it thoroughly.

        Water filter

        • Replace the water filter installed in the water automa- tic entry.

        Burner and pilot injector

        • Remove and clean the pilot burner.
        • Remove and clean the pilot injector.

        
        Without a water filter installed, turning on the heater is prohibited.

        Startup after maintenance work

        • Tighten all connections once more.
        • Read chapter 4 "Use" and chapter 5 "Adjustments".

        Heater purge

        In case of a frost risk, proceed as follows:

        

        • Remove the fixing lock from the filter screw cap (no. 1) situated in the water automatic.
        • Remove the filter screw cap (no. 2) from the water automatic.
        • Empty all the water contained in the heater.
          
          Fig. 16 Purging
        1. Lock
        2. Filter screw cap

        Combustion gas probe

        
        The probe must never be turned off, modified or replaced with a different part under any circumstances.

        Operation and precautions

        This probe verifies the conditions of flue evacuation and, in case of malfunction, it automatically turns off the heater. This prevents the combustion gases from entering the room where the gas heater has been installed. The probe restarts after a reset period.

        If the heater turns off during operation:

        • Ventilate the room.
        • 10 minutes later, turn on the heater once again. Call a qualified technician if the same thing happens again.

        
        The user must never touch the device.

        Maintenance

        If the probe malfunctions, proceed in the following manner:

        • Unscrew the probe fixing screw.
        • Detach the ignition unit terminal.
        • Replace the damaged part and proceed with its assembly using the steps indicated in the previous table, in reverse order.

        Operating check

        To check the correct operation of the combustion gas probe, proceed in the following manner:

        • Remove the combustion gases evacuation pipe.
        • Replace it with a pipe (approximately 50 cm long) blocked at one end.
        • The pipe must be routed vertically.
        • Turn on the heater at nominal power and with the temperature selector adjusted to maximum temperature.
          In these conditions, the heater must turn off two minutes afterwards, at most. Remove the pipe and replace the evacuation pipe.

        *Maintenance and Operating Check procedures must be performed by a qualified installer.

        Problems

        Problem/cause/solution

        Assembly, maintenance and repairs must be performed by qualified technicians only. The following chart offers solutions to possible problems (solutions followed by an * must be undertaken by qualified technicians only).

        • Gas supply.
        • Ignition system (ionisation electrode and electrovalves).

        

        Documents / Resources

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