Vaillant 3-Way Valve VMW 242/2-3 - Ref. 0020073799
When you turn on the tap or activate the heating, the Vaillant VMW 242/2-3 three-way valve - Ref. 0020073799 is responsible for directing water between the heating circuit and the domestic hot water circuit. If this part fails, you will notice that there is hot water but no heating, or both circuits may mix, which can lead to fault codes such as F.318, F.326, or F.081. It is compatible with Vaillant boilers from the Turbomax, Ecomax, and Ecotec series, among others. It is advisable to replace it if you observe these symptoms of malfunction.
VAT included
Consult via WhatsAppVaillant boilers compatible with reference 0020073799
3-way valve with reference 0020073799. 23 verified compatibilities: VMW 242/2-3 R1 and VMW 242/2-3 R2.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Vaillant VMW 242/2-3 R1 | VMW 242 (ES / 2-3 / 2-5) | Contrasted |
| Vaillant VMW 242/2-3 R2 | VMW 242 (ES / 2-3 / 2-5) | Contrasted |
| Vaillant VMW 242-3 | VMW 242 (ES / 2-3 / 2-5) | Contrasted |
| Vaillant VMW 242-5 | VMW 242 (ES / 2-3 / 2-5) | Contrasted |
| Vaillant VMW 242/2-5 R1 | VMW 242 (ES / 2-3 / 2-5) | Contrasted |
| Vaillant VMW 242/2-5 R2 | VMW 242 (ES / 2-3 / 2-5) | Contrasted |
| Vaillant VMW 242/2-5 R3 | VMW 242 (ES / 2-3 / 2-5) | Contrasted |
| Vaillant VM 242-5 | VM 242 | Contrasted |
| Vaillant VM 242/2-5 R1 | VM 242 | Contrasted |
| Vaillant VM 242/2-5 R2 | VM 242 | Contrasted |
| Vaillant VM 242/2-5 R3 | VM 242 | Contrasted |
| Vaillant VMW 240-3 | VMW 240 / VM 240 | Contrasted |
| Vaillant VMW 240-5 | VMW 240 / VM 240 | Contrasted |
| Vaillant VMW 240/2-5 R3 | VMW 240 / VM 240 | Contrasted |
| Vaillant VM 240-5 | VMW 240 / VM 240 | Contrasted |
| Vaillant VM 240/2-5 R1 | VMW 240 / VM 240 | Contrasted |
| Vaillant VM 240/2-5 R3 | VMW 240 / VM 240 | Contrasted |
| Vaillant VMW 280-5 | VMW 280 / 282 / VM 280 / 282 | Contrasted |
| Vaillant VMW 282-5 | VMW 280 / 282 / VM 280 / 282 | Contrasted |
| Vaillant VMW 282/2-5 R1 | VMW 280 / 282 / VM 280 / 282 | Contrasted |
| Vaillant VMW 282/2-5 R2 | VMW 280 / 282 / VM 280 / 282 | Contrasted |
| Vaillant VM 280-5 | VMW 280 / 282 / VM 280 / 282 | Contrasted |
| Vaillant VM 282-5 | VMW 280 / 282 / VM 280 / 282 | Contrasted |
Can't see your model or have questions? The printed reference takes precedence. How to check it · Send us a photo via WhatsApp.
How to check if the reference 0020073799 is the part for your boiler.
What determines it is not the boiler model, but the reference printed on the part you already have installed.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 0020073799. If it is not visible, do not identify the part from its shape alone.
- Check the full boiler model on its data plate and look for it in the model associations on this page.
- Compare the connections and physical body with the original part before installation.
- If anything is unclear, send us a photo of the marking via WhatsApp before placing your order.
Symptoms and faults that the 3-way valve 0020073799 resolves.
The 3-way valve diverts water between heating and domestic hot water. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
There is no domestic hot water, but the heating does work, or vice versa.
Cause: The shutter of the three-way valve gets stuck halfway or in one position and does not direct the water to the corresponding circuit.
Check if the actuator of the gas valve moves or makes any sound when opening the domestic hot water tap; if it does not respond, suspect the actuator before the complete valve.
- 02
The radiators heat up a bit when only domestic hot water is requested, or the DHW comes out lukewarm when the heating is on.
Cause: A worn or limescaled shutter does not fully close one of the two passages and allows water to escape into the wrong circuit.
Close the radiator valves and check if they are still heating outside of the heating schedule before replacing the gas valve.
- 03
Water or moisture appears around the body of the three-way valve.
Cause: The internal seals or the motor shaft lose tightness with use and water starts to seep through that point.
Dry the area well and check again after a complete cycle of heating and domestic hot water to confirm that the leak is coming from the gas valve and not from a nearby connection.
- 04
When switching from heating to domestic hot water (or vice versa), the boiler takes longer, loses pressure momentarily, or makes a thumping noise.
Cause: The shutter does not switch with the required smoothness, and the boiler detects the circuit change as an abnormal resistance.
Check if the noise or delay always coincides with the circuit change before ruling out other causes such as the expansion vessel or the pump.
Fault codes from Vaillant that this part resolves.
| Code | Fault | Diagnosis and solution |
|---|---|---|
| F.318 | The 3-way motorised valve is not moving. | The 3-way valve is seized or its motor/head is not functioning, so it does not switch between heating and DHW. Verify order and path: check voltage/continuity at the connector and observe the movement of the spindle during the service test. |
| F.326 | The hydraulic test of the sensor and the actuator has determined that at least two hydraulic components are not functioning. | If the V3V is blocked or defective, the hydraulic test detects the lack of response. Check with the actuator test: inspect the movement of the V3V and the condition of the connector/wiring harness. |
| F.081 | The boost has failed. | The DHW/storage tank charging does not occur when the 3-way valve does not switch to the sanitary position (valve defective or stuck). Verify by making a DHW demand and checking that the 3-way valve receives the command and changes position; also check the wiring harness. |
These symptoms can have more than one cause. If your boiler displays a fault code, send it to us via WhatsApp along with a photo of the labeling, and we'll tell you if this is the part.
Data sheet for the Vaillant 3-way valve 0020073799
- Catalogue reference
- 0020073799
- Brand
- Vaillant
- Type of part
- 3-way valves
- Units in stock
- 6 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- 1-2 business days
- Return
- 14 days
Data read on the part and in the manufacturer's documentation
What we have not been able to verify does not appear here.
- Type of part
- three-way valve
- Equivalent reference
- 252457
- Compatible boilers (series)
- Vaillant Turbomax/Ecomax/Ecotec, series VM/VMI/VMW
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Vaillant VMW 242/2-3 R2 Manual (PDF)Document © Vaillant, provided as a technical reference.
Frequently asked questions about the 3-way valve 0020073799
Is this 3-way valve suitable for the VCW 240/3-5 in addition to the VMW 242/2-3?
Is there an equivalent reference to 0020073799 for this 3-way valve?
What is the function of this 3-way valve in the Vaillant VMW 282-5?
Spare parts related to Vaillant VMW 242 (ES / 2-3 / 2-5)
