““FULLY REFURBISHED AND TESTED BY OUR ENGINEERS AND COME WITH 12 MONTH WARRANTY””

✅ What this part actually is

• Flow sensor / turbine (aqua sensor)
• Detects hot water demand (tap opening)
• Sends signal to PCB to fire boiler

👉 If faulty, boiler won’t detect flow properly

✅ Confirmed compatible boiler models

🔥 Vaillant ecoTEC Plus (major range)

• ecoTEC Plus 824 (all variants 246/3-5, 246/5-5 etc.)
• ecoTEC Plus 825
• ecoTEC Plus 831 (all R1–R5 variants)
• ecoTEC Plus 832 / 835 / 837 / 838
• ecoTEC Plus 937 / 938 (VUI storage combis)

👉 Covers most generations of ecoTEC Plus

🔥 Vaillant ecoTEC Pro

• ecoTEC Pro 24 (all variants)
• ecoTEC Pro 26
• ecoTEC Pro 28
• ecoTEC Pro 30

👉 Includes older and newer revisions

🔥 Vaillant ecoTEC Exclusive

• ecoTEC Exclusive 832
• ecoTEC Exclusive 838

🔥 Other ecoTEC variants

• VUW (combi) models
• VUI (storage combi) models
• Some regional condensing variants (Guernsey/Jersey models)

🧠 Key takeaway

• 178988 = very common Vaillant DHW flow sensor
• Used mainly in:
  • ecoTEC Plus
  • ecoTEC Pro
  • ecoTEC Exclusive
• Covers dozens of models (especially combis)

👉 If your boiler is ecoTEC combi → high chance this is correct

⚠️ Important (very common confusion)

This is often mixed up with:

• NTC sensors (temperature probes) ❌
• PRVs (178985 / 178988 confusion) ❌

👉 This one is specifically:
✔️ Flow detection (water movement)
NOT temperature or pressure

🔧 Common fault symptoms

• No hot water when tap opens
• Boiler doesn’t fire on DHW
• Intermittent hot water
• Low flow detection / error codes

👍 Practical advice

Before replacing:

• Check filter + plate heat exchanger (blockages mimic sensor faults)
• Check wiring to PCB

👉 These sensors do fail, but are often misdiagnosed