Combi Boiler 3-Way Valve Motor 220V, 7.5 mm Stroke, 65 N – Elbi (Bitron) Type 3165 | Compatible with Ariston 997147, Saunier Duval S5720600

Combi boiler 3-way (diverter) valve motor — in the manufacturer's own designation Motor for 3 way valve, Bitron Type 3165 family. It is the electric actuator that pushes the shaft of the 3-way valve, which switches between the heating circuit and domestic hot water.

The product comes in the original Bitron Service box; the code on the box and part label is 00316521000, electrical rating 220-240 V 50/60 Hz, stroke 7.5 mm, thrust 65 N, temperature class T70. The box carries the MADE IN EU marking, and the body has an embossed ENEC approval stamp.

🚨 7.5 mm Is Not the Shaft Diameter but the Shaft Travel

In the market this dimension is often written as shaft diameter; correctly it is the stroke — that is, the back-and-forth travel distance of the shaft. In the manufacturer's documentation it appears as travel / nominal stroke, and two different values are produced in this family: 7.5 mm or 10 mm. On top of this, an overstroke of approximately 3 mm is added; its purpose is not to make up for a stroke difference but to automatically compensate for the pressure on the valve seals over the life of the appliance.

How to measure the stroke of your own motor: remove the motor, pull the shaft out by hand all the way, and measure the distance with a ruler. If it is written on the label, simply read it from there.

🚨 What Decides Is Not the Boiler Model but the Label of the Old Motor

Boilers sold under the same brand and model name may have used motors with different strokes depending on the production year. For this reason, generalizations such as "Ariston is always 7.5 mm" or "Ariston is always 10 mm" cannot be made. Check these three before ordering:

• Voltage — 220-240 V AC or 24 V?
• Stroke — 7.5 mm or 10 mm?
• Plug type — on this product 3-pole flat faston terminals (6.3 × 0.8 mm).

If the wrong stroke is fitted: with a shorter stroke, the obturator cannot fully change position and both circuits remain partially open — the radiators also heat up when the tap is open, and hot water comes out lukewarm. With a longer stroke, the shaft bottoms out, the motor hits the end of the stroke and may draw excessive current, strip the plastic gears or burn out.

Failure Symptoms

• Radiators heat up but no hot water — the shaft is stuck in the heating position and the plate heat exchanger line cannot open.
• Radiators also heat up when hot water is turned on (even in summer) — the shaft cannot retract fully and water escapes into the heating circuit.
• Ticking or grinding noise — the plastic gears are stripped, or the motor is forcing a stuck shaft.
• The motor buzzes constantly and the shaft does not move.
• Water drips from under the boiler — the valve O-ring is worn; if water leaks into the motor, there is a risk of short circuit.
• Circulation / overheating warnings may appear on the PCB side.

Is the Motor Faulty or the Valve Cartridge? — Three Steps on Site

1. Ohm measurement: check the winding resistance between the socket terminals. If it is open circuit, the coil is finished.
2. Voltage check: when hot water is demanded, if 230 V is present at the socket but the shaft does not move, the motor is faulty. If there is no voltage, the problem is in the PCB or the cable.
3. Decisive test: remove the motor from the valve body and run the boiler with it free. If the shaft moves back and forth easily, the motor is sound — the problem is a scaled-up, seized valve cartridge.

🪤 The most common cause of failure is not the motor itself but a seized shaft. Limescale and sludge in the system hold the shaft, the motor draws excessive current while forcing it, and burns out. Before fitting the new motor, check that the cartridge piston moves freely by hand; if it is stuck, renew the cartridge as well, otherwise the new motor will soon meet the same fate.

🪤 Ease of installation: when replacing only the motor, there is no need to drain the system — removing the clip and disconnecting the plug is enough. When replacing the cartridge, however, the system is drained, then refilled to 1.2–1.5 bar and bled.

Compatible Original Codes

🪤 Note on the E.C.A. side: E.C.A. carries several different valve motors in its own spare parts list. Before ordering for your E.C.A. appliance, compare the voltage and stroke on the label of the removed motor with this product.

Compatible Models

If you do not see your model in the list, it does not mean this part does not fit; the decision is made using the three criteria above (voltage, stroke, plug type).

Technical Specifications

🪤 There is no fixed cable on the motor; the supply cable is a separate part.