Vaillant ecoTEC Plus VMW ES 306/5-5 Safety Valve Ref. 178985
When you open the hot water tap or turn on the heating, the Vaillant ecoTEC Plus VMW ES 306/5-5 Safety Valve is responsible for releasing water if the circuit pressure exceeds the usual limit. If this valve fails, you will notice that it drips continuously or does not discharge water when it should, which can cause problems in your boiler. It is compatible with models from the Atmoblock and Ecoblock ranges, such as the VMW 236/3-5 and VMW 306/5-5, among others. It should be replaced when you observe these symptoms to avoid further damage to the system.
VAT included
Consult via WhatsAppVaillant boilers compatible with reference 178985
Safety valve with reference 178985. Eight confirmed compatibilities: VMW 236/3-5 and VMW 242/4-5.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Vaillant VMW 236/3-5 | Atmoblock / Ecoblock (VMW compact wall-mounted mixed series) | Contrasted |
| Vaillant VMW 242/4-5 | Atmoblock / Ecoblock (VMW compact wall-mounted mixed series) | Contrasted |
| Vaillant VMW 306/5-5 | Atmoblock / Ecoblock (VMW compact wall-mounted mixed series) | Contrasted |
| Vaillant VMW 346/5-5 | Atmoblock / Ecoblock (VMW compact wall-mounted mixed series) | Contrasted |
| Vaillant VM 240/3-5 | VM series (wall-mounted heating only) | Contrasted |
| Vaillant VM 242/4-5 | VM series (wall-mounted heating only) | Contrasted |
| Vaillant VM 246/3-5 | VM series (wall-mounted heating only) | Contrasted |
| Vaillant VM 306/5-5 | VM series (wall-mounted heating only) | 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 ref. 178985 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 178985. 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 safety valve 178985 resolves
The safety valve releases pressure when the circuit exceeds its setting. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
Water is continuously leaking from the safety drain, even when the boiler is at rest.
Cause: The valve seat has lost its seal and allows water to pass through even though the pressure is normal.
Check the pressure gauge with the system cold: if it is above the usual level (around 1-1.5 bar), reduce the pressure before replacing the part, as it might be the circuit and not the valve.
- 02
After bleeding the boiler, the dripping from the valve does not stop.
Cause: A dirt particle has lodged in the seat after the release and is preventing it from closing completely.
Repeat the bleeding by operating the lever two or three times in a row to try to remove the dirt before replacing the valve.
- 03
The valve trips and expels water more frequently than normal, almost every time the boiler heats.
Cause: The expansion vessel is not properly absorbing the water expansions, and the excess is falling on the safety valve.
With the boiler cold and without water pressure, check the air pressure in the expansion vessel; if it's very low, that's the real cause of the trip, not the valve.
- 04
The boiler gradually loses pressure, and the pressure gauge drops day by day.
Cause: It is usually due to a slow drip from the valve that is not always visible because the water evaporates in the drain.
Dry the drain pipe thoroughly and check it a few hours later when it's cold; if it becomes wet again, confirm the leak through the valve before replacing it.
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 safety valve Vaillant 178985
- Catalogue reference
- 178985
- Brand
- Vaillant
- Type of part
- Safety valves
- Units in stock
- 1 unit
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- 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.
- CE marking
- CE
- Connection
- 1/2" (male thread)
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Vaillant VMW 346/5-5 Manual (PDF)Document © Vaillant, provided as a technical reference.
Frequently asked questions about the safety valve 178985
Is this safety valve suitable for the Vaillant VM 386/5-5?
When should I replace the safety valve of the Vaillant VM 240/3-5?
Spare parts related to Vaillant Atmoblock / Ecoblock (VMW compact wall-mounted combi series)
