Seko Twindose 35 Series Inst.. - UK

TWINDOSE 35 – System for dishwashers 

TWINDOSE 35 

Chemical Dosage Unit for Professional Dishwashing Machines 

TWINDOSE 35 code 0000136655 rev. 1.0 1


CONTENTS 

1 FIRST OF ALL 4 

1.1 WELCOME 4 

1.2 PACK CONTENTS 4 

1.3 TECHNICAL CHARACTERISTICS 5 

1.4 WARNINGS 5 

1.5 MATERIALS REQUIRED FOR INSTALLATION 5 

2 INSTALLATION 6 

2.1 INSTALLING THE SYSTEM 6 

2.2 DESCRIPTION OF THE FRONT PANEL 7 

2.2.1 Keys on the Front Panel 7 

2.2.2 LEDs on the Front Panel 7 

2.3 CIRCUIT DIAGRAM 8 

2.4 ELECTRICAL CONNECTIONS 9 

2.4.1 Fixed power supply and dishwashers with 2 solenoid valves (loading and rinsing) (Enclosure A) 9 

2.4.2 Fixed power supplies and dishwashers with 1 solenoid valve (Enclosure B) 10 

2.4.3 Power Supply from the Load and Rinse signals (Enclosure C) 10 

2.4.4 Electrical connection for the 3-pole conductometric sensor 11 

2.4.5 Electrical connection for the level sensor (optional) 11 

2.5 PLUMBING CONNECTIONS 12 

2.5.1 Plumbing connections for the detergent pump 12 

2.5.2 Plumbing connections for the rinse aid pump 13 

2.5.3 Plumbing connections for the sanitizer pump (only on 3-pump systems) 14 

2.6 INSTALLING THE CONDUCTOMETRIC SENSOR IN THE TANK 15 

3 DESCRIPTION AND SETTINGS FOR THE POTENTIOMETER DIP-SWITCHES & 

JUMPERS 16 

3.1 DESCRIPTION AND SETTINGS FOR THE DIP-SWITCHES 16 

3.2 DESCRIPTION AND SETTINGS FOR THE POTENTIOMETERS 17 

3.2.1 Potentiometer POT1: RINSE SPEED/TIME (Rinse Aid Pump: Speed / Time) 17 

3.2.2 Potentiometer POT2 (SANIT SPEED) 17 

3.2.3 Potentiometer POT3 (DETER RECHARGE/SET POINT) 17 

3.2.4 Potentiometer POT4 (OFA TIME) 18 

3.2.5 Potentiometer POT5 (DETER INIT CHARGE) 18 

3.3 DESCRIPTION AND SETTINGS FOR THE JUMPERS 19 

3.3.1 How to set the buzzer to the required volume 19 

3.3.2 Voltage setting range for the input signals 19 

4 PRIMING AND DE-LIMING MODE 19 

4.1 PRIMING 19 

4.2 DE-LIMING (DELIMING OF DISHWASHERS) 19 

5 SETTING AND OPERATION 20 

5.1 DETERGENT DOSING 20 

5.1.1 Dosing the detergent in conductometer mode (PROBE) 20 

5.1.2 Setting the concentration of detergent (SET POINT) 21 

5.1.3 Dosing the detergent in timer mode 22 

5.2 RINSE AID DOSING 22 

5.2.1 Dosing the rinse aid in by setting the volume (RINSE SPEED) 22 

5.2.2 Dosing the rinse aid by setting the timer (RINSE TIME) 22 

5.3 SANITIZER DOSING (ONLY 3-PUMP VERSIONS) 23 



6 OPERATING MODE 24 

6.1 PRIORITY OF INPUT SIGNALS 24 

6.2 SINGLE TANK DISHWASHING MACHINES (DOOR) – PROBE DOSING 25 

6.3 SINGLE TANK DISHWASHING MACHINES (DOOR) – PROBELESS DOSING 28 

6.4 CONVEYOR DISHWASHING MACHINES – PROBE DOSING 30 

6.5 CONVEYOR DISHWASHING MACHINES – PROBELESS DOSING 33 

7 LED DISPLAY 35 

7.1 LED DISPLAY DURING OPERATION 35 

7.1.1 Stand-by display 35 

7.1.2 Display during priming 35 

7.1.3 Display during dosing 35 

7.1.4 Display during DE-LIMING (de-liming of the dishwashing machine) 36 

7.2 ALARM LED DISPLAY 36 

7.2.1 Motor fault alarm (contact your local dealer) 36 

7.2.2 OFA1 Over Feed Alarm for excess dosing of detergent without the pumps cutting out 36 

7.2.3 OFA2 Over Feed Alarm for excess dosing of detergent with the pumps cutting out 36 

7.2.4 Level alarm without the detergent pump cutting out 37 

7.2.5 Level alarm without the rinse aid pump cutting out 37 

7.2.6 Level alarm without the sanitizer pump cutting out 37 

7.2.7 Level alarm wit the detergent pump cutting out 37 

7.2.8 Level alarm with the rinse aid pump cutting out 37 

7.2.9 Level alarm with the sanitizer pump cutting out 37 

8 MAINTENANCE AND ACCESSORIES 38 

8.1 MAINTENANCE 38 

8.1.1 Routine Inspection 38 

8.1.2 Replacement of peristaltic hoses for the dosing pump 38 

8.2 ACCESSORIES 38 

9 TROUBLESHOOTING 39 

9.1 THE POWER SUPPLY LED DOES NOT COME ON 39 

9.2 ONE OR MORE PUMPS ARE NOT RUNNING 39 

9.3 EXCESS DETERGENT 39 

9.4 TOO LITTLE DETERGENT 39 

9.5 EXCESS RINSE AID OR SANITIZER 39 

9.6 TOO LITTLE RINSE AID OR SANITIZER 39 

9.7 THE PUMP IS RUNNING TOO SLOWLY 39 

9.8 LOSS OF PRIMING ON THE DOSING PUMP 39 

9.9 ERROR MESSAGES VIA THE LED’s ON THE FRONT PANEL 39 

10 ENCLOSURE 40 

10.1 ENCLOSURE A “Fixed power supplies and dishwashers with 2 solenoid valves” 

40 

10.2 ENCLOSURE B “Fixed power supplies and dishwashers with 1 solenoid valve” 41 

10.3 ENCLOSURE C “Power Supply from the Load and Rinse signals” 42 

10.4 ENCLOSURE D “Summary of Alarms” 43 

11 HOW TO CONTACT SEKO 44 



1 FIRST OF ALL 

1.1 WELCOME 

TWINDOSE 35 is a microprocessor dosing system that has a LED display and that uses potentiometer and DIPswitch 

settings. 

This unit embodies SEKO’s advanced technology and combines easy installation with a wide range of functions. 

TWINDOSE 35 has been designed to be used with all types of dishwashing machines (single tank and conveyor). 

The range available includes a series of models that are able to suit all the client’s needs. 

The concentration of the detergent solution is detected and kept unchanged by means of a conductometric sensor 

(to be installed inside the dishwasher) or by a timer control. Any shortage of the detergent dosed is picked up by 

the system’s OFA alarm function, which measures the detergent dosing time and, once the set time has expired, it 

warns the end user of the required concentration not having been reached by means of an buzzer. The rinse aid is 

dosed by means of a peristaltic pump, with either the pump rotation speed or the dosing time being set. The 

sanitizer (DLL or LLL versions only) is dosed by a peristaltic pump on which the speed is set. All settings are done 

using the keys on the front panel and potentiometers and DIP-switches that are clearly visible on the circuit. 

This manual contains instructions for configuring the TWINDOSE 35 to allow you to make use of all the advantages 

offered by the simplest and most versatile dosing system on the market. 

Please read this manual carefully, paying particular attention to the warnings and cautions related to 

the installation procedures. Always apply the necessary safety procedures, including the use of adequate 

personal protective equipment for your face, eyes, hands, and clothing. 

1.2 PACK CONTENTS 

Before starting work, make sure that the pack contains the following: 

• Box complete with peristaltic pumps. 

• Foot filter (2) (3 for DLL and LLL versions) 

• Detergent injector (1) 

• Injection coupling with non-return valve (Rinse aid dosing) (1) 

• Sanitizer injector (1)* 

• T connector for rinse aid injector (1) 

• Fixing bracket with screws and wall plugs (1) 

• Conductometric sensor (1) 

• Conductometric sensor installation kit (1) 

• Jumpers (2) 

* Only on 3-pump versions 



1.3 TECHNICAL CHARACTERISTICS 

• Power Supply: 80 - 265 Vac (24 Vac using additional optional module) 50/60 Hz 

• Signal voltage range that can be selected using Jumpers: 20 - 265 Vac or 150 - 265 Vac 

• Consumption: 20 W 

• Fuses: 200mA DELAY 

• Detergent pump capacity: 1,3 - 12,50 lit/h 

• Rinse aid pump capacity: 0,25 - 2,50 lit/h at 3 bar 

• Sanitizer pump capacity: 0,25 – 2,5 lit/h at 3 bar 

• Maximum operating conductivity: 10 mS (5 mS default) 

• System Protection Rating: IP 65 

• Weight: 3,5 kg 

• Dimensions: Version LL • LLL W 285 x H 220 x D 110 

Version DL • DLL W 360 x H 220 x D 110 

1.4 WARNINGS 

Make sure that the pressure at the rinse aid injection point is not higher than 3 bar. 

Check that the suction hoses are inserted in the jelly cans for the correct products. 

Use a multimeter to check all the electrical connections on the TWINDOSE 35. Applying the incorrect 

voltage could permanently damage the equipment and such damage is not covered by the guarantee. Do 

not connect to power supplies subject to widely fluctuating voltages and/or peak currents. When forming 

any electrical connections, refer to the wiring diagram in this manual. 

Check the voltage on the main power supply and make sure that it is between 80 and 265 Vac. 

WARNING: TWINDOSE 35 provides high voltage at the transformer connection. Always switch off the 

power supply before doing any maintenance work on the equipment. 

WARNING: During installation and when forming electrical connections, disconnect all power supplies 

to the dishwasher. 

Failure to respect the standards laid down in this manual could harm people or property, and either 

compromise the way the equipment operates or damage it. 

1.5 MATERIALS REQUIRED FOR INSTALLATION 

• Two-pole cable: 2x1 - H-05 RNF for the external power supply 

• Two-pole cable: 2x1- H-05 RNF for the signal and conductometric sensor connection. 

• Suction and discharge hoses in Crystal PVC for the detergent pump. 

• Suction hose in Crystal PVC for the rinse aid suction pump. 

• Discharge hose in polythene for the rinse aid delivery pump. 

• Suction hose in Crystal PVC for the sanitizer suction pump (only on 3-pump systems). 

• Discharge hose in polythene for the sanitizer delivery pump (only on 3-pump systems). 



2 INSTALLATION 

Attach the equipment to a wall near the dishwashing machine, using the wall anchors supplied in the pack. It is 

best to keep the equipment at a height that is within 1,5 m of the level of the liquid to be sucked up. 

Before proceeding with installation, observe all applicable legal prescriptions related to electrical and plumbing 

connections to make sure that the system is installed safety and correctly. Refer to the wiring diagram for the 

dishwashing machine when forming electrical connections. 

WARNING: Do not fit the equipment in the way of steam outlets as this could cause a short circuit, 

resulting in permanent damage to the equipment. 

Installing the TWINDOSE 35 near the steam vents from the dishwasher may cause the TWINDOSE 35 

circuit to overheat, which could cause damage or result in difficulty with the way the equipment operates. 

2.1 INSTALLING THE SYSTEM 

• Find a suitable position for installing the TWINDOSE 35. 

• Use the brackets and fixings supplied for installation. 

• Using the bracket as a drilling template, mark out the position of the holes. 

• Use a drill to make the holes in the wall. 

• Put the wall plugs in the holes. 

• Fix the brackets in position (flat side against the wall with the holes at the bottom), using the screws provided. 

• Insert the bracket you have just fixed to the wall into its seating in the back of the TWINDOSE 35 (Fig. 1). 

• To open the TWINDOSE 35, unscrew the upper screws on the front cover by ¼ turn, and hold the cover until it 

is fully open. 

Fig. 1 



2.2 DESCRIPTION OF THE FRONT PANEL 

1 3* 

C D E* 

2 

A 

B 

2.2.1 Keys on the Front Panel 

1 DETERGENT PRIME: Key used to prime the detergent pump. 

2 RINSE AID PRIME: Key used to prime the rinse aid pump. 

3 *SANITIZER PRIME: Key used to prime the sanitizer pump. 


2.2.2 LEDs on the Front Panel 

A Power: Power supply LED, green, permanently on or flashing (see Chap. 7) 

B Alarm: Alarm LED, red, permanently on or flashing (see Chap. 7) 

C Detergent: Detergent pump LED, green, permanently on or flashing 

(see Chap. 7) 

D Rinse aid: Rinse aid pump LED, green, permanently on or flashing 

(see Chap. 7) 

E *Sanitizer: Sanitizer pump LED, green, permanently on or flashing 

(see Chap. 7) 




2.3 CIRCUIT DIAGRAM 

1 2 3 4 5 6 7 8 9 10 11 12 13 

AC 

OUT 

DET 

AC 

OUT 

RINSE 

AC 

OUT 

SANI 

1 2 3 4 5 

AC MAINS AC MAINS 

DETERGENT RINSE 

CHARGE 

SIGNAL 

6 7 8 

RINSE 

9 10 

WASH 

SIGNAL SIGNAL 

14 15 16 

11 12 

ALARM 

OUT 

13 14 15 16 17 18 19 20 21 22 23 24 

DETER RINSE SANIT TEMP COND PROBE 

INPUT SIGNAL PROBE 

LOW-HIGH 

HIGH-LOW 

LOW-HIGH 

HIGH-LOW 

20 21 22 

LOW-HIGH 

HIGH-LOW 

17 18 19 

DC OUT DET 

DC OUT RINSE 

DC OUT SANI 

23 

+7.5V 

-7.5V 

+5V 

DOOR 

PROBELESS 

COND PROBE 

RINSE SPEED 

SANI W/DET 

RINSE LIM OFF 

LEV STOP OFF 

CONVEYOR 

PROBE 

IND PROBE 

RINSE TIME 

SANI W/RINSE 

RINSE LIM ON 

LEV STOP ON 

POT 1 

RINSE 

SPEED 

TIME 

POT 2 

SANIT 

SPEDD 

HIGH 

AUDIO 

LOW 

DETER 

RECHARGE OFA 

SETPOINT TIME 

POT 3 

POT 4 

24 

POT 5 

DETER 

INIT CHRG 

25 

26 27 28 29 30 

Fig. 3 

1 AC MAINS DETERGENT: entry fuse 16 Sanitizer AC motor output 

2 AC MAINS DETERGENT: detergent signal input 17 Detergent DC motor output 

3 AC MAINS RINSE: rinse aid signal input 18 Rinse aid DC motor output 

4 AC MAINS RINSE: entry fuse 19 Sanitizer DC motor output 

5 CHARGE SIGNAL: charge signal input 20 

Voltage range selection jumper for charge signal 

input 

6 RINSE SIGNAL: rinse signal input 21 

Voltage range selection jumper for rinse signal 

input 

7 WASH SIGNAL: wash signal input 22 

Voltage range selection jumper for wash signal 

input 

8 Alarm relay output 23 

Input from optional module for 24 Vac power 

supply. 

9 Detergent level signal input 24 Buzzer volume selector 

10 Rinse aid level signal input 25 DIP-switch for programming the system 

11 Sanitizer level signal input 26 

POT1: Rinse pump speed / rinse pump dosing 

time 

12 Temperature probe connector 27 POT2: Sanitizer pump speed 

13 Conductometric sensor connector 28 

POT3: Detergent pump reset time / Conductivity 

set point setting 

14 Detergent AC motor output 29 POT4: OFA time setting 

15 Rinse aid AC motor output 30 POT5: Initial detergent pump charge time 



2.4 ELECTRICAL CONNECTIONS 

WARNING: TWINDOSE 35 provides high voltage at the transformer connection. Always switch off the 

power supply before doing any maintenance work on the equipment. 

Use a multimeter to check all the electrical connections on the TWINDOSE 35. Applying the incorrect 

voltage could permanently damage the equipment and such damage is not covered by the guarantee. 

Do not connect to power supplies subject to widely fluctuating voltages and/or peak currents. When 

forming any electrical connections, refer to the wiring diagram in this manual. All wiring must be carried 

out in compliance with local regulations for electrical connections. 

2.4.1 Fixed power supply and dishwashers with 2 solenoid valves (loading and rinsing) (ENCLOSURE A). 

• Check the voltage on the main power supply and make sure that it is the same as that shown on the 

TWINDOSE 35’s data plate. 

• Disconnect the dishwasher from the electrical power supply. 

• Check the voltage on the charge and rinse solenoid valves on the dishwasher and insert the relevant jumpers 

JP1 and JP2 in the HIGH (150 – 265 Vac) or LOW (20 – 265 Vac) positions, depending on whether you are 

using 220 Vac or 24 Vac solenoid valves. 

• Connect the main power supply wires to terminals 3 and 4 (AC MAINS RINSE) 

• Connect the 1 st charge signal wires to terminals 5 and 6 (CHARGE SIGNAL) on the circuit board. 

• Connect the rinse signal wires to terminals 7 and 8 (RINSE SIGNAL) on the circuit board. 

• If you want to use the system with the conductometric sensor, connect the wires for the washing pump 

contactor coil to terminals 9 and 10 (WASH SIGNAL) on the circuit board. 

When doing this, check the voltage on the washing pump contactor coil and insert Jumper JP3 in the HIGH 

(150 – 265 Vac) or LOW (20 – 265 Vac) position, depending on whether it is a 220 Vac or 24 Vac coil. 

• When using the rinse aid pump in timer mode for single tank dishwashers, it is advisable to connect terminals 7 

and 8 electrically to the coil on the dishwashers’ washing pump contactor coil. In this case rinse aid will be 

dosed to the boiler during the washing stage for use in the next rinse cycle. 

TWINDOSE 35 is fitted with a switching feeder that allows it to be powered using voltages of between 

80 and 265 Vac. 

When connecting up the conductometric sensor, refer to paragraph 2.6 and enclosure A, at the end of 

this manual. 



2.4.2 Fixed power supplies and dishwashers with 1 solenoid valve (ENCLOSURE B) 

• Check the voltage on the main power supply and make sure that it is the same as that shown on the 

TWINDOSE 35’s data plate. 


• Check the voltage on the dishwasher’s rinse solenoid valve and insert Jumper JP2 in the HIGH (150 – 265 Vac) 

or LOW (20 – 265 Vac) position, depending on whether you are using a 220 Vac or 24 Vac solenoid valve. 

• Connect the main power supply cables to terminals 3 and 4 (AC MAINS RINSE) 

• Connect the rinse signal wires to terminals 7 and 8 (RINSE SIGNAL) on the circuit board. 

• If you want to use the system with the conductometric sensor, connect the wires for the washing pump 

contactor coil to terminals 9 and 10 (WASH SIGNAL) on the circuit board. 

When doing this, check the voltage on the dishwasher’s washing pump contactor coil and insert Jumper JP3 in 

the HIGH (150 – 265 Vac) or LOW (20 – 265 Vac) position, depending on whether it is a 220 Vac or 24 Vac coil. 

• When using the rinse aid pump in timer mode for single tank dishwashers, it is advisable to connect terminals 7 

and 8 electrically to the dishwashers’ washing pump contactor coil. In this case rinse aid will be dosed to the 

boiler during the washing stage for use in the next rinse cycle. 

TWINDOSE 35 is fitted with a switching feeder that allows it to be powered using voltages of between 

80 and 265 Vac. 

When connecting up the conductometric sensor, refer to paragraph 2.6 and enclosure B, at the end of 

this manual. 

2.4.3 Power Supply from the Load and Rinse signals (ENCLOSURE C) 

• Check the voltage on the charge and rinse solenoid valves and make sure that it is the same as that shown on 

the TWINDOSE 35’s data plate. 


• Check the voltage on the charge and rinse solenoid valves on the dishwasher and insert the relevant jumpers 

JP1 and JP2 in the HIGH (150 – 265 Vac) or LOW (20 – 265 Vac) positions, depending on whether you are 

using 220 Vac or 24 Vac solenoid valves. 

• Connect the rinse solenoid valve to terminal 3-4 (AC MAINS RINSE) on the circuit board. 

• Connect the charge solenoid valve where fitted to terminal 1-2 (AC MAINS DETERGENT) on the circuit board. 

• Form a bridge between terminals 3-4 and terminals 7-8. 

• Form a bridge between terminals 1-2 and terminals 5-6. 

• If you want to use the system with the conductometric sensor, connect the wires for the dishwasher’s washing 

pump contactor coil to terminals 9 and 10 (WASH SIGNAL) on the circuit board. 

When doing this, check the voltage on the dishwasher’s washing pump contactor coil and insert Jumper JP3 in 

the HIGH (150 – 265 Vac) or LOW (20 – 265 Vac) position, depending on whether it is a 220 Vac or 24 Vac coil. 



2.4.4 Electrical connection for the 3-pole conductometric sensor 

Connect the wires for the probe to the (COND PROBE) terminals 21, 22, and 24, with the colouring as 

follows: (See paragraph 2.6 and Enclosures). 

• Blue on terminal 21 

• Brown on terminal 22 

• Yellow-Green on terminal 24. 

For instructions on fitting the conductometric sensor, see paragraph 2.6 and ENCLOSURES. 

For best results we recommend using a copper trefoil wire of 20 AWG or less, for the probe connection. Do not 

lay the cable near high voltage electrical lines. 

2.4.5 Electrical connection for the level sensor (optional) 

Connect the detergent level probe wires to the DETER INPUT SIGNAL 13-14 terminal on the circuit board. 

Connect the rinse aid level probe wires to the RINSE INPUT SIGNAL 15-16 terminal on the circuit board. 

Connect the sanitizer* level probe wires to the SANIT INPUT SIGNAL 17-18 terminal on the circuit board. 




2.5 PLUMBING CONNECTIONS 

2.5.1 Plumbing connections for the detergent pump 

To install the detergent pump, proceed as follows: 

Suction 

• Insert the suction hose into the flat side of the stainless steel weight. 

• Insert the hose sticking out of the countersunk part of the stainless steel weight into the foot filter. 

• Secure the pipe by pushing the weight against the filter and rotating it until it matches perfectly (Figure 5). 

• Cut a sufficient length of detergent suction hose to reach the detergent pump. 

• Put the suction hose into the ring nut. 

• Insert the hose into the suction side of the detergent pump. 

• Tighten the fixing ring nut by hand on the suction side of the detergent pump. 

Stainless steel weight 

Fig. 5 

Suction hose 

Foot filter 

Delivery 

• Fit the delivery hose on the delivery side of the detergent pump, after inserting it into the relevant ring nut. 

• Cut a sufficient length of detergent delivery hose to reach the point at which it is injected into the tank. 

• Fix the other end of the delivery hose to the injection coupling after having inserted it in the relevant ring nut. 

• Make a 10 mm diameter hole in the vertical side of the tank, just above the water level, and fit the injection 

coupling as shown in the drawing (Figure 6). 

• Tighten the fixing ring nut on the injection coupling and the pump by hand. 

Fig. 6 

1 TANK SIDE 

2 INJECTION COUPLING 

3 DELIVERY HOSE 

4 GASKET 

5 WASHER 

6 NUT 

7 WATER LEVEL 

Always use the foot filter and make sure it reaches the bottom of the tank. Clean out any residue 

regularly. 



2.5.2 Plumbing connections for the rinse aid pump 

To install the rinse aid pump, proceed as follows: 

Suction 




• Cut a sufficient length of rinse aid suction hose to reach the rinse aid pump. 


• Insert the hose into the suction side of the rinse aid pump. 

• Tighten the fixing ring nut by hand on the suction side of the rinse aid pump. 


Fig. 7 

Suction hose 

Delivery 

• Insert the delivery hose into the fixing ring nut on the non-return valve. 

• Fix the hose to the non-return valve. 

• Cut a sufficient length of delivery hose to connect it between the delivery side of the rinse aid pump (right) and the 

non-return valve. 

• Install the non-return valve between the rinse solenoid valve and the boiler, using the specific provision made on 

the boiler, or the T coupling included in the pack. (Fig. 8) 

• Tighten the ring nuts on the non-return valve and the pump by hand. 

Delivery hose 

Foot filter 

T connector 

Non-return valve 

Fig. 8* 

Metallic clumps 

* Installation using a plastic T connector is recommended. 


regularly. 



2.5.3 Plumbing connections for the sanitizer pump (only on 3-pump systems). 

To install the sanitizer pump, proceed as follows: 

Suction 




• Cut a sufficient length of sanitizer suction hose to reach the sanitizer pump. 


• Insert the hose into the suction side of the sanitizer pump. 

• Tighten the fixing ring nut by hand on the suction side of the sanitizer pump. 


Fig. 9 

Suction hose 

Foot filter 

Delivery 

• Insert the delivery hose into the fixing ring nut on the injection valve. 

• Fix the hose to the injection valve. 

• Cut a sufficient length of delivery hose to connect it between the delivery side of the sanitizer pump (right) and the 

injection valve. 

• Tighten the ring nuts on the injection valve and the pump by hand. 

Fig. 10 


regularly. 



2.6 INSTALLING THE CONDUCTOMETRIC SENSOR IN THE TANK 

The probe detects the concentration of detergent. Correct positioning of the probe is essential for adequately 

checking of the concentration of detergent. Always use the new probe supplied with the TWINDOSE 35. The 

probe must be positioned where it is constantly immersed in the solution in the washing tank, in a position in which 

there is an adequate flow of the solution, and near the point at which the product enters. 

• Install the probe in the washing tank, below the water level. 

• If you are not able to find an existing hole, it may be advisable to use a 22.2 mm cutter or punch. 

• Always install the probe: 

o Far from the point at which the water enters the tank. 

o Near the circulation pump intake. 

o Far from corners, heating elements, or the bottom of the tank. 

• Remove the probe fixing nut. 

• Remove a rubber gasket and the plastic washer. 

• Insert the probe with the rubber gasket into the hole from the inside of the dishwasher tank. 

• Fit the rubber gasket and the washer. 

• Put on the nut and tighten it using a spanner if necessary. 

• Wire up the probe using a wire (not supplied) applying the colour coding and using the Faston clip and cap 

supplied, as shown in the instructions given in the diagram below. 

• Connect the wires from the terminals on the probe to terminals 21,22, and 24 on circuit board, connecting the 

colours as indicated in the figure and in enclosures A, B, and C. 

• For best results we recommend using a copper trefoil wire of 18 AWG for the probe connection. Do not lay the 

cable near high voltage AC lines. 

DISHWASHER SIDE 

WATER LEVEL 

FIXING NUT 

PROBE 

WASHER 

RUBBER GASKETS 

HOW TO CONNECT UP THE CONDUCTIVITY PROBE 

COME COLLEGARE LA SONDA CODUTTIVA 

FIT THE PROBE INSIDE THE TANK BEFORE FITTING THE CAP OVER THE FASTON CLIPS 

MONTARE LA SONDA IN VASCA PRIMA DI INSERIRE IL CAPPUCCIO SUI FASTON 

BLUE 

YELLOW-GREEN 

GIALLO/VERDE 

BROWN MARRONE 

BLUE 

YELLOW- 

GIALLO/VERDE 

GREEN 

BROWN MARRONE 

BLUE 

YELLOW- 

GIALLO/VERDE 

GREEN 

MARRONE BROWN 

WIRE NOT 

SUPPLIEDT 

YELLOW-GREEN 

GIALLO/VERDE 

MARRONE BROWN 

BLU BLUE 

21 22 23 24 

COND PROBE 

WARNING: ATTENZIONE!!! FORM ESEGUIRE THE CONNECTION IL COLLEGAMNETO AS SHOWN IN SECONDO THE DIAGRAM FIGURA 

To replace the probe, cut the wire immediately before the male Faston clip. 



3 DESCRIPTION AND SETTINGS FOR THE POTENTIOMETER DIP-SWITCHES & 

JUMPERS 

3.1 DESCRIPTION OF THE DIP-SWITCHES 

CAL. OFF 

CAL. ON 

DIP 

Switch 

1 

2 

3 

4 

5 

6 

7 

8 

ON/OFF 

ON 

OFF 

ON 

OFF 

ON 

OFF 

ON 

OFF 

ON 

OFF 

ON 

OFF 

ON 

OFF 

ON 

OFF 

OFF 

Setting 

System set for conveyor dishwasher (CONVEYOR) 

System set for single-tank dishwasher (DOOR) 

Operation with conductometric sensor 

Operation without conductometric sensor (timer mode) 

System with inductive probe 

System with conductive probe. 

Rinse aid pump in timer mode 

Rinse aid pump is speed mode 

Probe calibration ON 

Probe calibration OFF 

Sanitizer pump activated along with the rinse aid pump. 

Sanitizer pump activated along with the detergent pump. 

Rinse aid pump limitation activated - under all conditions the rinse aid pump will dose for a 

maximum of 15 seconds. 

Rinse aid pump limitation deactivated - the pump will dose for the entire time set in the washing 

program. 

Cut-out level alarm enabling - when a level signal is received, the system cuts out dosing by all the 

pumps. 

Cut-out level alarm disabling- when a level signal is received an alarm LED will simply switch on, 

but the pumps will not be stopped. 

To prime the detergent pump, press the “DETERGENT PRIME” key 

To prime the rinse aid pump, press the “RINSE-AID PRIME” key 

To prime the sanitizer pump, press the “SANITIZER PRIME” key 

ON 



3.2 DESCRIPTION OF THE POTENTIOMETERS 

3.2.1 Potentiometer POT1: RINSE SPEED/TIME (Rinse Aid Pump: Speed / Time) 

3.2.2 

0 sec** 255 sec** 

10%* 100%* 

POT1 is a multi-function potentiometer that is used to regulate dosage by the rinse aid pump. 

• If RINSE SPEED* mode has been selected using DIP-switch 4, potentiometer POT1 will regulate the pump’s 

dosage flow rate between 10 and 100%. 

• If RINSE TIME** mode has been selected using DIP-switch 4, potentiometer POT1 will regulate the pump’s 

dosage time, between 0 and 255 seconds. 

* If volumetric dosage mode has been selected (speed regulation) 

** If the timer dosage mode has been selected. 

3.2.2 Potentiometer POT2 (SANIT SPEED) 

10% 100% 

Potentiometer POT2 is used to regulate sanitizer pump dosing, by adjusting the flow rate between 10 and 100%. 

3.2.3 Potentiometer POT3 (DETER RECHARGE/SET POINT) 

0 sec** 255 sec** 

10%* 100%* 

POT3 is a multi-function potentiometer that is used to set dosage by the detergent pump. 

• Where DIP-switch 2 (PROBELESS / PROBE) has been used to select dosage in conductometric sensor 

(PROBE)* mode, potentiometer POT3 will set the set point for the required detergent concentration. 

• Where DIP-switch 2 (PROBE / PROBELESS) has been used to select dosage in timer** mode, potentiometer 

POT3 will regulate the detergent pump’s dosage time during rinsing, between 0 and 255 seconds. 

* If the conductometric sensor dosage mode has been selected. 

** If the timer dosage mode has been selected. 



3.2.4 Potentiometer POT4 (OFA TIME) 

1s. 

Disabled 

255 sec 

The OFA alarm is activated when the detergent concentration in the tank does not reach the set point within the 

time set using the POT4 (OFA TIME) potentiometer. 

As soon as detergent dosage begins, TWINDOSE 35 doses in conductometric mode (with probe) for the OFA time 

set using the POT4 (OFA TIME) potentiometer. Once this period of time has expired, if the detergent pump is still 

running the system goes into an OFA1 alarm phase: 

• The alarm LED flashes. 

• The buzzer sounds intermittently. 

• During this initial phase the pumps do not cut out. 

This alarm status ends if the detergent pump stops before the second OFA time (OFA2) has expired. 

If the detergent pump continues dosing for a further OFA interval, the device enters a second OFA phase, known 

as OFA2. 

During this alarm phase (OFA2): 

• The buzzer sounds continuously. 

• The LED stays lit permanently. 

• The detergent pump stops. 

PLEASE NOTE: The detergent pump will not start up again. To reset proper functioning, eliminate the 

cause of the alarm and then switch the system off and on again. 

The OFA time can be set using the POT4 (OFA TIME) trimmer, for a period of between 1 second and 255 

seconds. 

To disable the OFA alarm, turn the POT4 (OFA TIME) trimmer all the way to the left. 

3.2.5 Potentiometer POT5 (DETER INIT CHARGE) 

1sec 

255 sec 

This potentiometer manages the dosing time for the detergent pump during the first charging phase, and it is 

activated when TWINDOSE 35 receives a signal on the CHARGE SIGNAL terminal. 

The time setting can vary between 1 and 255 seconds. 



3.3 DESCRIPTION AND SETTINGS FOR THE JUMPERS 

3.3.1 How to set the buzzer to the required volume 

The buzzer volume can be set using jumper JP4 (N° 24 on page 5) to HIGH or LOW volume, or it can be disabled. 

• Select HIGH for loud volume. 

• Select LOW for quiet volume. 

• Remove the jumper to exclude the buzzer. 

3.3.2 Voltage range setting for the input signals 

TWINDOSE 35 is fitted with 3 jumpers that are used to select the voltage range that is accepted by the terminals 

used for the signals from the dishwasher’s CHARGE SIGNAL (First Charge Signal), RINSE SIGNAL, and WASH 

SIGNAL. 

These jumpers are numbered JP1, JP2, and JP3 and are described under numbers 20, 21, and 22 in paragraph 

2.3. 

These jumpers can be set to: 

• HIGH: In this case the voltage range accepted by the terminals used for the signals coming from the 

dishwasher is between 150 and 265 Vac. 

• LOW: In this case the voltage range accepted by the terminals used for the signals coming from the 

dishwasher is between 20 and 265 Vac. 

4 PRIMING AND DE-LIMING MODE 

4.1 PRIMING 

• When the RIN PRIME button on the front panel is pushed, the rinse aid pump runs at top speed. To prime 

the pump the system must be fed. 

• When the DET PRIME button on the front panel is pushed, the detergent pump runs at top speed. To prime 

the pump the system must be fed. 

• When the SAN PRIME button on the front panel is pushed (only LLL and DLL versions), the sanitizer pump 

runs at top speed. To prime the pump the system must be fed. 

4.2 DE-LIMING (DE-ENCRUSTING OF DISHWASHERS) 

The system can include a special stand-by status that allows the dishwashing machine to be cleaned without 

having to switch it off. 

To enter DELIME mode, push DETERGENT PRIME and RINSE PRIME simultaneously. 

In DELIME mode, TWINDOSE 35 does not recognise any input signal, thereby disabling any type of dosing, even 

when the dishwasher is running. 

When in DELIME mode, the DET LED flashes, the RIN LED flashes, the SAN LED flashes, and the ALARM 

LED flashes. The buzzer cannot sound, the alarm relay is deactivated, and the pumps are stopped. 

To exit DELIME mode simply return to operating mode by pushing any key. 



5 SETTING AND OPERATION 

5.1 DETERGENT DOSING 

5.1.1 Dosing the detergent in conductometric mode (PROBE) 

To set the machine to conductometric sensor (PROBE) detergent dosing mode, switch the DIP-switch 2 to the 

“ON” (PROBE) position. The pump doses at top speed until the set point is reached. 

CAL. OFF 

CAL. ON 

When TWINDOSE 35 receives a signal from the dishwasher’s washing pump on its IN WASH terminal, the 

conductometric sensor detects the concentration in the tank. When the concentration drops below the set point, 

set using potentiometer POT3, the control circuit automatically activates the detergent pump and stops when the 

conductivity in the tank rises more than 10% higher than the set point. 

The detergent pump’s speed depends on how much the concentration in the tank differs from the set point: 

• When the concentration in the tank is below 80% of the set point, the pump doses at top speed. 

• When the concentration in the tank is between 80% and 90% of the set point, the pump doses at 50% of its 

top speed. 

• When the concentration in the tank is above 90% of the set point, the pump doses at 25% of its top speed. 

If TWINDOSE 35 does not receive a signal on its IN WASH terminal, the control circuit will not activate detergent 

dosage, even if the concentration of detergent in the tank is below the set point. 

If the correct concentration of detergent is not reached within the two OFA time intervals set, the “OFA2” alarm 

is activated automatically and detergent dosage stops. 

In this alarm state, the LED configuration is as follows. 

• DET LED: flashing 

• ALARM LED: lit permanently 

• The buzzer sounds continuously. 

• The alarm relay output is activated. 

To reset the alarm status, eliminate the cause and restart the system. 



5.1.2 Setting the concentration of detergent (SET POINT) 

Only when using a conductometric sensor 

The setting and maintenance of the correct concentration of detergent is extremely important for obtaining 

acceptable results while keeping costs down. 

The dosage unit’s conductometric sensor measures the electrical conductivity of the water and detergent solution. 

This conductivity depends on the alkalinity (strength of detergent), water temperature (at higher temperatures the 

conductivity is higher) and hardness of the water. 

The conditions that affect the dosage of detergent are constantly changing. Some of the factors that are changing 

continually include temperature, hardness of the water, degree of dilution, the different chemical effects caused by 

different food residues, external contamination (introducing the incorrect product), etc. 

It is highly unlikely that these conditions will be exactly the same two days running. 

For this reason it is not possible to relate the concentration of the detergent to the conductivity scale on the 

TWINDOSE 35. 

The method most commonly used involves regulating the concentration on the basis of previous experience in 

relation to the type of detergent, water conditions and the type of dishwashing machine. 

The method explained below is more scientific, and is recommended when previous experience in the field does 

not make it easy to determine the set point for the concentration in the tank: 

Set the DIP-switch as shown below. 

CAL. OFF 

CAL. ON 

• It is not necessary to remove the suction hose from the detergent jerry can, since the system uses the buzzer to 

indicate when the set point, based on the concentration of the solution in the tank, has been stored in the 

memory, without starting the pumps. 

• Go to calibration mode by switching DIP-switch 5 to the ON (CAL ON) position. 

• Turn potentiometer POT 3 anticlockwise until it stops turning. 

• Shut off the dishwasher’s drain, fill the tank with water and add the amount of detergent calculated in order to 

obtain the correct concentration or titration value. 

• Start the dishwasher and wait for the water to reach operating temperature. 

• Check titration and adjust the concentration as required. 

• With the dishwasher running, slowly adjust the concentration (slowly turn POT3 clockwise) until the buzzer 

sounds. 

• Switch the dishwasher off. 

• Switch the DIP-switch to the OFF (CAL OFF) position to return to operating mode. 



5.1.3 Dosing the detergent in timer mode 

To select the timer mode for the detergent pump, DIP-switch 2 must be switched to the OFF (PROBELESS) 

position. The pump will run at top speed for the time set using potentiometer POT3. 

CAL. OFF 

CAL. ON 

In this configuration, POT4 regulates the detergent dosing time during the rinsing phase, while detergent dosing 

during the 1 st charging phase is controlled by potentiometer POT5 that sets the dosing time when a signal is 

received on the CHARGE SIGNAL terminal. 

5.2 RINSE AID DOSING 

When the TWINDOSE 35 unit receives a signal on the RINSE SIGNAL terminal, the rinse aid pump doses in terms 

of a volumetric (speed) setting or timer setting, depending on the selection made using DIP-switch 4 (RINSE 

SPEED / RINSE TIME). 

5.2.1 Dosing the rinse aid in by setting the volume (RINSE SPEED) 

CAL. OFF 

CAL. ON 

If the volumetric (RINSE SPEED) dosing mode is selected: 

• Set DIP-switch 4 (RINSE SPEED / RINSE TIME) to RINSE SPEED (OFF position). 

• Set the rinse aid pump flow rate to between 0% and 100% of the top speed (using potentiometer POT1). 

To change the pump speed, simply turn potentiometer POT1 clockwise to increase speed and anticlockwise to 

reduce speed. 

5.2.2 Dosing rinse aid by setting the timer (RINSE TIME) 

CAL. OFF 

CAL. ON 

If the timer dosing mode is selected: 

• Set DIP-switch 4 (RINSE SPEED / RINSE TIME) to RINSE TIME (ON position). 

• Set the dosing time for the rinse aid pump to between 1 and 255 seconds (using potentiometer POT1). 

To change the pump dosing time, simply turn potentiometer POT1 clockwise to increase and anticlockwise to 

reduce. 



5.3 SANITIZER DOSING (only 3-pump versions) 

CAL. OFF CAL. ON CAL. OFF CAL. ON 

“ON” Position 

“OFF” Position 

The sanitizer pump can be set to dose at the same time as the detergent or the rinse aid pump. This setting is 

done using DIP-switch 6 (SANI W/DET-SANI W/RINSE): 

• In the “ON” position (SANI W/RINSE) the sanitizer pump is activated at the same time as the rinse aid pump. 

• In the “OFF” position (SANI W/DET) the sanitizer pump is activated at the same time as the detergent pump. 

Install the sanitizer injection fitting to suit the mode chosen. 

Dosage of the sanitizer takes place as per the volumetric flow rate setting. 

Potentiometer POT2 (SANIT SPEED) can be used to set the motor speed between 5 and 100% of the top speed. 



6 OPERATING MODE 

This system can be set for installation on single-tank type (DOOR) dishwashers or conveyor (CONVEYOR) type 

dishwashers. In both cases it can be set to work in conductometric mode (with a probe). 

The type of dishwasher is selected using DIP-switch 1: 

CAL. OFF 

CAL. ON 

The choice of dosing the detergent in conductometric (PROBE) or timer (PROBELESS) mode is made using DIPswitch 

2. 

CAL. OFF 

CAL. ON 

6.1 PRIORITY OF INPUT SIGNALS 

• The system can handle a maximum of 3 signals coming from the dishwasher. 

• 1 st charge (CHARGE SIGNAL) 

• RINSE SIGNAL 

• WASH SIGNAL 

The CHARGE SIGNAL enjoys priority over the others. 

The RINSE SIGNAL and WASH SIGNAL enjoy equal priority. This means that activation of one does not 

exclude activation of the other (which means that they can be active at the same time). 



6.2 SINGLE-TANK WASHING MACHINES (DOOR) – PROBE DOSING MODE 

This mode is set using the DIP-switches in this layout: 

CAL. OFF 

CAL. ON 

 

CHARGE SIGNAL 

DETERGENT PUMP 

When the signal from the solenoid valve, which controls the 1° charge signal, is activated, the detergent pump 

doses for a set time (between 0 and 255 seconds) using the potentiometer POT5 (DETER INIT CHRG) 

DETER 

INIT CHRG 

The set dosing time will be completed even if the charge signal is de-activated during the dosing. 

RINSE AID PUMP 

In this phase, the rinse aid pump is not activated. 

0 sec. 255 sec. 

SANITIZER PUMP (ONLY 3-PUMP VERSIONS) 

The sanitizer pump (optional) is activated simultaneously with the detergent pump only if previously set with the 

DIP-switch 6 in the “OFF” position (SANI W/DET) 

CAL. OFF 

CAL. ON 

If DIP-switch 6 is set in the “ON” position (SANI W/RINSE), the sanitizer pump will not be activated. 



 

RINSE SIGNAL 


The detergent pump is not controlled in this mode. 


When the signal from the solenoid valve, which controls the rinsing, is activated the rinse aid pump is activated in 

the time mode or in the speed mode, depending on how the DIP-switch 4 was set. 

• If it is set in the RINSE SPEED mode, the rinse aid pump will dose at the set speed using the potentiometer 

POT1 for the whole duration of the rinsing signal. 

• If it is set in the RINSE TIME mode, the rinse aid pump will dose at the maximum speed for the time set using 

the potentiometer POT1. 

In both cases, if the RINSE LIM ON mode is set using the DIP-switch 7, the rinse aid pump will stop dosing after 15 

seconds independently from the set time or from the duration of the RINSE SIGNAL. In order to de-activate this 

function, move the DIP-switch 7 to the left (RINSE LIM OFF) 

CAL. OFF 

CAL. ON 

. 

WARNING 

If the RINSE LIM ON mode is activated and the rinse aid pump is set in time for a duration of less than 15 seconds, 

the pump will dose for the set time using the POT1. 


The sanitizer pump (optional) is activated simultaneously with the rinse aid pump only if the DIP-switch 6 is set in 

the “ON” position (SANI W/RINSE) 

CAL. OFF 

CAL. ON 

If DIP-switch 6 is set in the “OFF” position (SANI W/DET), the sanitizer pump will not be activated. 



 

WASH SIGNAL 


When this signal is activated, the detergent pump is activated only if the conductometric sensor detects a 

concentration of detergent inferior to the set point in the tank. 

When the concentration value detected in the tank falls below the set point, the control circuit automatically 

activates the detergent pump and stops when the concentration in the tank rises more than 10% above the set 

value. 

If TWINDOSE 35 does not receive any signal from the WASH SIGNAL terminal, the control circuit does not 

activate dosage of the detergent, not even if the conductometric sensor detects that the detergent concentration is 

below the set point. 

If the desired concentration of detergent (set point) is not reached within the time set by the OFA using the POT4 

(OFA TIME): 

• the buzzer alarm sounds intermittently 

• the alarm LED flashes OFA1 ALARM 

• the relay output is activated 

• the pumps continue running. 

If the correct concentration of detergent is not reached within two OFA time intervals 

• the buzzer alarm emits a continuous sound 

• the LED alarm stays on OFA2 ALARM 

• the relay output is activated 

• the pumps stop running. 



The rinse aid pump is not controlled by the WASH SIGNAL. 


The sanitizer pump (optional) is activated simultaneously with the detergent pump only if previously set with the 


CAL. OFF 

CAL. ON 


WARNING 

The RINSE SIGNAL and the WASH SIGNAL have equal priority, this means that the system can control them 

simultaneously and therefore activate the detergent pump (controlled by the WASH SIGNAL) and the rinse aid 

pump (controlled by the RINSE SIGNAL). 

Obviously, the sanitizer pump is activated according to whatever is set using the DIP-switch 6. 



6.3 SINGLE-TANK DISHWASHING MACHINES (DOOR)- PROBELESS DOSING 

This mode is set using the DIP-switches in this configuration: 

CAL. OFF 

CAL. ON 

 

CHARGE SIGNAL 


When the signal from the solenoid valve that controls the 1 st charge signal is activated, the detergent pump doses 

for a time (between 0 and 255 seconds) set using potentiometer POT5 (DETER INIT CHRG). 

DETER 

INIT CHRG 

The dosing time set will be completed even if the charge signal is de-activated during dosing. 


In this phase, the rinse aid pump is not activated. 

0 sec. 255 sec. 

SANITIZER PUMP (only 3-pump versions) 

The sanitizer pump (optional) is activated simultaneously with the detergent pump only if previously set by putting 


CAL. OFF 

CAL. ON 




 

RINSE SIGNAL 


When the signal from the solenoid valve, which controls the RINSE SIGNAL, is activated, the detergent pump 

doses for a time (between 0 and 30 seconds) set using potentiometer POT3 (DETER RECHARGE). 

DETER 

RECHARGE 

SET POINT 

0 sec 30 sec 

The dosing time set will be completed even if the dosing signal is de-activated during dosing. 


When the signal from the solenoid valve that controls rinsing is activated, the rinse aid pump is activated in time 

mode (RINSE TIME) or in speed mode (RINSE SPEED), depending on how DIP-switch 4 was set. 

• If it is set for RINSE SPEED mode, the rinse aid pump will dose at the speed set using potentiometer POT1 

for the whole duration of the rinsing signal. 

• If it is set for RINSE TIME mode, the rinse aid pump will dose at top speed for the time set using 

potentiometer POT1. 

In both cases, if the RINSE LIM ON mode is set using the DIP-switch 7, the rinse aid pump will stop dosing 

after 15 seconds independently of the time set or the duration of the RINSE SIGNAL. 

In order not to set this rinse aid dosing limit, move DIP-switch 7 (RINSE LIM OFF) to the left. 

CAL. OFF 

CAL. ON 

WARNING 

If RINSE LIM ON mode is activated and the rinse aid pump is set to time (RINSE TIME option) for a dosing time of 

less than 15 seconds, the pump will dose for the time set using POT1, ignoring the LIMIT OFF/LIMIT ON option. 

SANITIZER PUMP (only 3-pump versions) 

The sanitizer pump is activated simultaneously with the detergent pump only if previously set by moving DIP-switch 

6 to the “OFF” position (SANI W/DET). Alternatively, it is activated simultaneously with the rinse aid pump if DIPswitch 

6 is set to the “ON” position (SANI W/RINSE) 



 

WASH SIGNAL 

In this configuration, the WASH SIGNAL is not managed, since in single-tank probeless (DOOR-PROBELESS) 

mode, the detergent concentration control takes place without a conductometric sensor, using the timed dosing 

mode (PROBELESS). 

6.4 CONVEYOR DISHWASHING MACHINES (CONVEYOR) – PROBE DOSING 

This mode is set by setting the DIP-switches in this configuration: 

CAL. OFF 

CAL. ON 

 

CHARGE SIGNAL 


When the signal from the solenoid valve that controls the 1 st charge signal is activated, the detergent pump doses 


DETER 

INIT CHRG 

0 sec 255 sec 



The rinse aid pump is not activated. 

SANITIZER PUMP (OPTIONAL) 

The sanitizer pump (optional) is activated simultaneously with the detergent pump only if previously set by moving 

DIP-switch 6 to the “OFF” position (SANI W/DET). 

CAL. OFF 

CAL. ON 




 

RINSE SIGNAL 


The detergent pump is not controlled. 


When the rinse signal is activated, the rinse aid pump doses at the speed set using potentiometer POT1: 

RINSE 

SPEED 

TIME 

0% 100% 

If the RINSE LIM ON mode is set using DIP-switch 7, the rinse aid pump will stop dosing after 15 seconds 

independently of the time set or the duration of the RINSE SIGNAL. In order not to set this rinse aid dosing 

limit, turn DIP-switch 7 (RINSE LIM OFF) to the left. 

CAL. OFF 

CAL. ON 


The sanitizer pump (optional) is activated simultaneously with the rinse aid pump only if DIP-switch 6 is set in the 

“ON” position (SANI W/RINSE) 

CAL. OFF 

CAL. ON 

If DIP-switch 6 is set in the “OFF” position (SANI W/DET), the sanitizer pump will not be activated. 





 

WASH SIGNAL 


When this signal is activated, the detergent pump is activated only if the conductometric sensor detects a 

concentration of detergent in the tank, below the set point. 

When the concentration value detected in the tank falls below the set point, the control circuit automatically 

activates the detergent pump and stops when the concentration in the tank rises more than 10% above the set 

value. 

If TWINDOSE 35 does not receive any signal from the WASH SIGNAL terminal, the control circuit does not 

activate dosage of the detergent, even if the conductometric sensor detects that the detergent concentration is 

below the set point. 

If the required concentration of detergent (set point) is not reached within the time set by the OFA using POT4 

(OFA TIME): 

• The buzzer alarm sounds intermittently. 

• The alarm LED flashes OFA 1 ALARM 

• The relay output is activated 

• The pumps continue dosing. 

If the correct concentration of detergent is not reached within two OFA time intervals 

• The buzzer alarm sounds continuously. 

• The LED alarm stays on OFA 2 ALARM 

• The relay output is activated 

• The pumps stop dosing. 




6.5 CONVEYOR DISHWASHING MACHINES – PROBELESS DOSING 

This mode is set using the DIP-switches in this configuration: 

CAL. OFF 

CAL. ON 


When the signal from the solenoid valve that controls the 1st charge signal is activated, the detergent pump doses 


DETER 

INIT CHRG 

0 sec 255 sec 



In this configuration, the rinse aid pump is not activated. 


The sanitizer pump (optional) is activated simultaneously with the detergent pump only if previously set by moving 

DIP-switch 6 to the “OFF” position (SANI W/DET) 

CAL. OFF 

CAL. ON 




 

RINSE SIGNAL 


When the RINSE SIGNAL is activated, the detergent pump runs in ON-OFF mode for a time set using 

potentiometer POT3 (between 0 and 30 seconds) and switches off for 15 seconds. 

The pump continues to switch on and off in this mode, for the entire duration of the RINSE SIGNAL. 

DETER 

RECHARGE 

SETPOINT 

0 sec 30 sec 

PUMP START TIME 

(TIME ON) 


When the rinse signal is activated, the rinse aid pump doses at the set speed for the entire duration of the RINSE 

SIGNAL. 

The speed at which the pump doses depends on the setting on potentiometer POT1: 

RINSE 

SPEED 

TIME 

0% 100% 

If RINSE LIM ON mode is set using DIP-switch 7, the rinse aid pump will stop dosing after 15 seconds even if the 

RINSE SIGNAL continues longer. 

In order to allow the pump to run for the entire duration of the RINSE SIGNAL, set “RINSE LIMIT OFF” mode 

using DIP-switch 7. 


The sanitizer pump is activated simultaneously with the detergent pump only if previously set with DIP-switch 6 in 

the “OFF” position. Alternatively, it is activated simultaneously with the rinse aid pump if DIP-switch 6 is set in the 

“ON” position. 

 

WASH SIGNAL 

In Conveyor-Probeless mode the WASH SIGNAL is not controlled. 

TWINDOSE 35 code 0000136655 rev. 1.0 35


7 LED DISPLAY 

A whole series of messages are indicated both during operation and in case of malfunction or alarm status, using 

the LEDs on the front panel of the TWINDOSE 35. 

7.1 LED DISPLAY DURING OPERATION 

C D E* 

7.1.1 Stand-by display 

A 

B 

The green LED A (power) stays on, this LED shows that the TWINDOSE 35 is switched on. 

The buzzer and the relay output are de-activated. 

7.1.2 Display during priming 



• DETERGENT PUMP PRIMING: The green LED C (detergent) stays on 

• RINSE AID PUMP PRIMING The green LED D (rinse aid) stays on 

• SANITIZER PUMP PRIMING: The green LED E (sanitizer) stays on 

7.1.3 Display during dosing 



• DETERGENT PUMP DOSING The green LED C (detergent) stays on 

• RINSE AID PUMP DOSING The green LED D (rinse aid) stays on 

• SANITIZER PUMP DOSING The green LED E (sanitizer) stays on 

7.1.4 Display in DELIME mode 



• The red LED B (alarm) flashes 

• The green LED C (detergent) flashes 

• The green LED D (rinse aid) flashes 

• The green LED E (sanitizer) flashes 

*Only in the 3 pump systems 



7.2 ALARM LED DISPLAY 

7.2.1 Motor fault alarm (contact your local dealer) 


The buzzer sounds for 1 second every 10 seconds. 

• The red LED B (alarm) flashes 



• The green LED E (sanitizer) flashes 

7.2.2 Over feed alarm OFA1: abnormal detergent dosage without pumps cutting out 

This alarm goes off if during dosing with a conductometric sensor, the detergent concentration in the tank is not 

reached within an OFA time set by potentiometer POT 4 (OFA TIME). 


• The buzzer sounds intermittently. 

• The relay output is enabled. 

• The red LED B (alarm) flashes. 

• The green LED C (detergent) stays on. 

7.2.3 Over feed alarm OFA2: abnormal detergent dosage with pumps cutting out 

This alarm goes off if during dosing with a conductometric sensor, the detergent concentration in the tank is not 

reached within 2 OFA times. 


• The buzzer sounds continuously 

• The relay output is enabled 

• The red LED B (alarm) stays on 





7.2.4 Detergent level alarm without pumps cutting out 


• The buzzer sounds intermittently 


• The detergent pump is ready to dose 



7.2.5 Rinse aid level alarm without pumps cutting out 



• The relay output is turned on 

• The rinse aid pump is ready to dose 



7.2.6 *Sanitizer level alarm without pumps cutting out 




• The sanitizer pump* is ready to dose 


• The green LED E* (sanitizer) flashes 

7.2.7 Detergent level alarm with pumps cutting out** 

This function can be excluded by selecting LEV STOP OFF on DIP-switch 8 






• The pumps cut out 

7.2.8 Rinse aid level alarm with pumps cutting out** 








7.2.9 Sanitizer level alarm with pumps cutting out** 






• The green LED D (sanitizer) flashes 





8 MAINTENANCE & ACCESSORIES 

8.1 MAINTENANCE 

Routine maintenance of the TWINDOSE 35 involves taking out any encrustations that may have formed on the 

probe’s electrodes. 

It will also be necessary to change the peristaltic tubes for the detergent, rinse aid and sanitizer dosing pumps 

whenever they are found to have deteriorated. 

Thanks to SEKO technology, maintenance time is reduced to a minimum. Maintenance can be carried out on site, 

without having to remove the product. 

8.1.1 Routine Inspection 

• Titrate the solution in the washing tank to check that the equipment is maintaining the correct concentration. 

• Clean the conductometric or inductive sensor. 

• Clean the TWINDOSE 35 casing using only a damp cloth. 

• Check the plumbing efficiency of the suction and discharge hoses. 

IT IS ADVISABLE TO DESCALE THE DISHWASHING MACHINE REGULARLY IN ORDER TO AVOID 

COMPROMISING CORRECT FUNCTIONING OF THE CONDUCTIVITY SENSORS. 

8.1.2 Replacing the peristaltic hoses on the dosing pump 

Replace the pump hoses at regular intervals. Hoses should be replaced long before they become weak and burst. 

Should a hose burst, remove all the chemical product left in the pump, using a damp cloth. 

• Switch off the power supply before doing any maintenance work on the equipment. 

• Take the transparent lid off of the pump, removing the front cover screws if necessary 

• Before removing the old hose, position the roller arm in such a way that the rollers are in a vertical position. 

• Remove the old tube, starting from the left 

• Lift the tube and simultaneously rotate the roller arm clockwise. 

• Before inserting the new hose, put the roller arm in a horizontal position. 

• Insert the new tube with the connections placed in such a way that the flat sides are towards the front. 

• Insert the new tube starting from the left and simultaneously rotate the roller arm clockwise. 

• Make sure that the peristaltic tube is correctly positioned inside the pump. 

• Insert the front transparent cover all the way, putting the screws back in if necessary. 

8.2 ACCESSORIES 

• Two-pole cable: 2x0.75 - H-05 RNF 

• T connector in PP for injection in the sanitizer pump 

• Intake nozzles with or without level probe. 

• Low-bulk tank side-connector, made of in PP, for injecting detergent. 



9 TROUBLESHOOTING 

9.1 THE POWER LED (POWER) DOES NOT SWITCH ON 

• Check the fuses in the circuits. 

• Check that the voltage at the circuit’s power terminals is correct. For details on the data plate and the 

connections diagram, refer to this manual. 

9.2 ONE OR MORE PUMPS ARE NOT RUNNING 

• Check the terminals on the circuit for the pump motor for any loose screws or disconnected wires. 

• Check that the voltage on the signal terminals is correct. For details on the data plate, refer to this manual. 

9.3 EXCESS DETERGENT 

• Check the voltage on the power supply to the system. 

• Check that the concentration set point was set correctly. 

• Make sure that there are no encrustation or foreign objects on the conductometric sensor that would 

compromise the correct reading of the concentration in the tank. 

• Make sure that the dosing time for the detergent pump has not been set at excessively high values. 

9.4 TOO LITTLE DETERGENT 

• Check the voltage on the power supply to the system. 

• Check that the concentration set point was set correctly. 

• Check the efficiency of the conductometric sensor. 

• Make sure that the dosing time for the detergent pump has not been set at excessively low values. 

• Check for possible chemical product leaks on the delivery line. 

9.5 EXCESS RINSE AID OR SANITIZER 

• Make sure that the dosing time or speed for the pump have not been set at excessively high values. 

9.6 TOO LITTLE RINSE AID OR SANITIZER 

• Make sure that the dosing time or speed for the pump have not been set at excessively low values. 

• Check for possible chemical product leaks on the delivery line. 

9.7 THE PUMP RUNS TOO SLOWLY 

• Check that the roller block has not seized. 

• Check lubrication of the flexible hose. 

9.8 LOSS OF PRIMING ON THE DOSING PUMP 

• Check the suction line for holes. 

• Check that the pump’s peristaltic hoses are not cracked or punctured. 

• Check that the peristaltic hoses are not worn. 

9.9 ERROR MESSAGES VIA THE LEDS ON THE FRONT PANEL 

Refer to paragraph 7.2 of this manual and if necessary contact your local dealer. 



10 ENCLOSURE 

ENCLOSURE A 

10.1 “FIXED POWER SUPPLY AND DISHWASHERS WITH 2 SOLENOID VALVES” 

WITH CONDUCTIVITY PROBE 

SONDA CONDUCTIVITY CONDUCIBILITA' PROBE 

CONDUTTIVA 

CHARGE ELETTROVALVOLA 

SOLENOID 

VALVE 

DI CARICO 

RINSE ELETTROVALVOLA 

SOLENOID 

VALVE 

DI RISCIACQUO 

WASHING CONTATTORE MOTOR 

CONTACTOR 

MOTORE DI LAVAGGIO 

SONDE LEVEL PROBES DI LIVELLO 

L N 

1 2 3 4 5 

AC MAINS AC MAINS 

DETERGENT RINSE 

CHARGE 

SIGNAL 

6 7 8 9 10 

RINSE 

SIGNAL 

WASH 

SIGNAL 

AC 

OUT 

DET 

AC 

OUT 

RINSE 

AC 

OUT 

SANI 

11 12 

ALARM 

OUT 

13 14 15 16 17 18 19 20 21 22 23 24 



LOW-HIGH HIGH-LOW 

LOW-HIGH HIGH-LOW 

LOW-HIGH 

HIGH-LOW 

DC OUT DET 

DC OUT RINSE 

DC OUT SANI 

BLUE 

MARRONE 

BROWN 

YELLOW-GREEN 

GIALLO/VERDE 

DOOR 

PROBELESS 

COND PROBE 

RINSE SPEED 

CONVEYOR 

PROBE 

IND PROBE 

RINSE TIME 

RINSE 

SPEED 

TIME 

SANIT 

SPEDD 

DETER 

RECHARGE 

SETPOINT 

HIGH 

AUDIO 

LOW 

OFA DETER 

TIME INIT CHRG 

SANI W/DET 

RINSE LIM OFF 

LEV STOP OFF 

SANI W/RINSE 

RINSE LIM ON 

LEV STOP ON 

POT 1 

POT 2 

POT 3 

POT 4 

POT 5 



ENCLOSURE B 

10.2 FIXED POWER SUPPLY AND DISHWASHERS WITH 1 SOLENOID VALVE 

WITH CONDUCTIVITYPROBE 

RINSE SOLENOID 

ELETTROVALVOLA 

VALVE 

DI RISCIACQUO 

WASHING MOTOR 

CONTATTORE 

CONTACTOR 

MOTORE DI LAVAGGIO 

SONDA CONDUCIBILITA' 

CONDUCTIVITY PROBE 

CONDUTTIVA 

SONDE LEVEL DI PROBES LIVELLO 

L N 

1 

2 

AC MAINS 

DETERGENT 

3 4 

AC MAINS 

RINSE 

5 6 

CHARGE 

SIGNAL 

7 8 

RINSE 

SIGNAL 

WASH 

9 10 

SIGNAL 

AC 

OUT 

DET 

AC 

OUT 

RINSE 

AC 

OUT 

SANI 

13 14 15 16 17 18 19 20 21 22 23 24 


11 

INPUT SIGNAL 

ALARM 

12 PROBE 

OUT 

HIGH-LOW 

LOW-HIGH 

HIGH-LOW 

LOW-HIGH 

HIGH-LOW 

LOW-HIGH 

DC OUT DET 

DC OUT RINSE 

DC OUT SANI 

BLUE 

MARRONE BROWN 

YELLOW-GREEN 

GIALLO/VERDE 

DOOR 

PROBELESS 

COND PROBE 

RINSE SPEED 

CONVEYOR 

PROBE 

IND PROBE 

RINSE TIME 

RINSE 

SPEED 

TIME 

SANIT 

SPEDD 

DETER 

RECHARGE 

SETPOINT 

HIGH 

AUDIO 

LOW 

OFA DETER 

TIME INIT CHRG 

SANI W/DET 

RINSE LIM OFF 

LEV STOP OFF 

SANI W/RINSE 

RINSE LIM ON 

LEV STOP ON 

POT 1 

POT 2 

POT 3 

POT 4 

POT 5 



ENCLOSURE C 

10.3 POWER SUPPLY FROM THE LOAD AND RINSE SIGNALS 

WITH CONDUCTIVITY PROBE 

CHARGE SOLENOID 

VALVE ELETTROVALVOLA 

DI CARICO 

RINSE SOLENOID 

VALVE ELETTROVALVOLA 

DI RISCIACQUO 

WASHING MOTOR 

CONTACTOR 

SONDA CONDUCTIVITY CONDUCIBILITA' PROBE 

CONDUTTIVA 

SONDE 

LEVEL 

DI 

PROBES 

LIVELLO 

AC 

OUT 

DET 

1 

2 3 4 5 6 

CHARGE 

SIGNAL 

AC MAINS 

DETERGENT 

AC MAINS 

RINSE 

7 8 

RINSE 

SIGNAL 

9 10 

WASH 

SIGNAL 

11 12 

ALARM 

OUT 

13 14 15 16 17 18 19 20 21 22 23 24 



HIGH-LOW 

LOW-HIGH 

HIGH-LOW 

LOW-HIGH 

HIGH-LOW 

LOW-HIGH 

DC OUT DET 

DC OUT RINSE 

DC OUT SANI 

AC 

OUT 

RINSE 

AC 

OUT 

SANI 

BLUE 

MARRONE BROWN 

GIALLO/VERDE 

YELLOW-GREEN 

DOOR 

PROBELESS 

COND PROBE 

RINSE SPEED 

SANI W/DET 

RINSE LIM OFF 

LEV STOP OFF 

CONVEYOR 

PROBE 

IND PROBE 

RINSE TIME 

SANI W/RINSE 

RINSE LIM ON 

LEV STOP ON 

POT 1 

RINSE 

SPEED 

TIME 

SANIT 

POT 2 SPEDD 

HIGH 

AUDIO 

LOW 

DETER 

RECHARGE OFA DETER 

SETPOINT TIME INIT CHRG 

POT 3 

POT 4 

POT 5 



10.4 ALARM SUMMARY 

ENCLOSURE D 

LED DET LED RIN LED SAN LED ALARM BUZZER RELA 

Y 

MOTOR 

S 

DELIME 

PRIMIN 

G DET 

PRIMIN 

G RIN 

PRIMIN 

G SAN 

MOT 

DET ON 

MOT RIN 

ON 

MOT 

SAN ON 

MOTOR 

FAULT 

ALARM 

OFA1 

OFA2 

DET LEV 

DOES 

NOT 

CUT 

OUT 

RIN LEV 

DOES 

NOT 

CUT 

OUT 

SAN LEV 

DOES 

NOT 

CUT 

OUT 

DET LEV 

CUTS 

OUT 

RIN LEV 

CUTS 

OUT 

SAN LEV 

CUTS 

ON 

(FLASHING) 

ON 

PERMANENTL 

Y 

OFF 

ON 

(FLASHING) 

ON 

(FLASHING) 

ON 

(FLASHING) 

OFF OFF OFF 

OFF OFF OFF OFF OFF DET ON 

MAX 

SPEED 

ON 

OFF OFF OFF OFF RIN ON 

PERMANENTL 

MAX 

Y 

SPEED 

OFF OFF ON 

PERMANENTL 

Y 

OFF OFF OFF SAN ON 

MAX 

SPEED 

OFF OFF OFF OFF OFF OFF DET ON 

ON 

PERMANENTL 

Y 

ON 

PERMANENTL 

Y 

OFF OFF ON 

PERMANENTL 

Y 

ON 

(FLASHING) 

ON 

PERMANENTL 

Y 

ON 

(FLASHING) 

ON 

(FLASHING) 

OFF 

ON 

(FLASHING) 

OFF OFF OFF OFF RIN ON 

ON 

(FLASHING) 

OFF OFF OFF SAN ON 

ON 

(FLASHING) 

- - ON 

(FLASHING) 

- - ON 

PERMANENTL 

Y 

OFF OFF ON 

PERMANENTL 

Y 

ON 

(FLASHING) 

OFF 

OFF OFF ON 

(FLASHING) 

ON 

(FLASHING) 

OFF 

ON 

PERMANENTL 

Y 

ON 

PERMANENTL 

Y 

OFF OFF ON 

PERMANENTL 

Y 

ON 

(FLASHING) 

OFF 

OFF OFF ON 

(FLASHING) 

ON 

PERMANENTL 

Y 

ON 

PERMANENTL 

ON 

PERMANENTLY 

ON 

(INTERMITTENT 

ON 

PERMANENTLY 

ON 

(INTERMITTENT 

ON 

(INTERMITTENT 

ON 

(INTERMITTENT 

) 

ON 

ON 

ON 

ON 

ON 

ON 

OFF 

ON 

OFF 

ON 

ON 

ON 

ON ON OFF 

ON ON OFF 

ON ON OFF 



OUT 

Y ON 



11 HOW TO CONTACT SEKO 

Seko 

Website: www.seko.com 

SEKO Asia Pacific 

SEKO Brazil 

SEKO China 

SEKO Deutschland 

SEKO France 

SEKO Iberica 

SEKO Italia 

SEKO Russia 

SEKO Southern Africa 

SEKO UK 

SEKO USA

Seko Twindose 35 Series Inst.. - UK

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