3 Bar Safety Valve Vaillant Ecotec Plus VMW 296/3-5

Vaillant boilers compatible with reference 178985

Safety valve with reference 178985. Eight confirmed compatibilities: VMW 236/3-5 and VMW 242/4-5.

Proven compatibility

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

The part reference, model, and equipment revision must be verified against the manufacturer's documentation.

1. 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.
2. Check the full boiler model on its data plate and look for it in the model associations on this page.
3. Compare the connections and physical body with the original part before installation.
4. If anything is unclear, send us a photo of the marking via WhatsApp before placing your order.

Symptoms that require diagnosis in the safety valve 178985

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 gas valve outlet, even with the boiler turned off.

  Cause: The seat does not seal properly because there is scale or the circuit pressure is very close to the 3 bar of this valve.

  Check the pressure gauge with the boiler cold: if it reads more than 1.5 bar approximately, bleed the circuit and check if the dripping stops.

• 02

  It leaks water just when starting the heating, with the boiler still cold.

  Cause: The expansion vessel does not compensate for the expansion of the water, and the pressure rises quickly to nearly 3 bar.

  Check the air precharge of the expansion vessel before changing the gas valve: if it is low, it does not cushion and the valve activates prematurely.

• 03

  The pressure in the circuit is gradually decreasing without any visible leak.

  Cause: A small and intermittent drip from this gas valve may dry up between bleedings and not be evident.

  Look for limescale or dry water marks just below the discharge outlet: if they are there, the gas valve has been leaking for a while.

• 04

  The circuit reaches more than 3 bar and the gas valve does not activate.

  Cause: The mechanism may be seized up due to scale if it has not been bled manually for a long time.

  With the cold system, pull the bleed ring or lever to check if it releases water and then close it properly.

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

Uniclima internal SKU

VSEPVMW296

Brand

Vaillant

Type of part

Safety valves

Units in stock

3 units

Status

Refurbished

Warranty

1 year

Shipping

Delivery time shown at checkout

Return

14 days

Part data and available documentation

Contrast the label codes, PCB, and revision with the installed part; they are not necessarily equivalent references.

fool

3 bar

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.