Vaillant
Vaillant 178985 Pressure relief valve, 3 bar
Vaillant 178985 3 bar pressure relief valve for the hydraulic circuit of Vaillant heating appliances; opens at 3 bar to discharge excess pressure.
At a glance
- Part type: Hydraulics
- Also known as 1375069, N6751
Showing prices
£344.40
£287.00 ex. VAT · VAT at 20%
In stock
Cut-off passed — dispatches next working day
Not certain it's the right part? The technical team verifies fitment before dispatch — no charge, and it stops a second trip.Call the technical teamSend a technical question
Same-day dispatch
Ordered by 4pm Mon–Fri, 10:30am Sat.
30-day returns
Unused, in original packaging.
What it is
The Vaillant 178985 is a 3 bar pressure relief valve forming part of the hydraulic group in Vaillant domestic heating appliances. It is a safety valve that opens once system pressure reaches its 3 bar set point, discharging water to protect the appliance and the wider heating circuit from over-pressurisation. It is supplied as a single unit and carries a 1 year manufacturer guarantee.
Signs this part needs replacing
- Water weeping or running from the discharge pipe while the system is cold
- System pressure gauge climbing above the normal cold fill pressure
- Pressure dropping repeatedly, requiring frequent top-ups
- Discharge pipe still wet or dripping after the heating has been off for some time
- Scale, debris or staining visible around the valve outlet or seat
Before you order
- Confirm 178985 matches the number on the existing valve or in the appliance's parts list
- Check the appliance serial and GC number against the manufacturer's documentation
- Have a suitable sealing washer or fibre gasket to hand in case the existing one is disturbed on removal
- Isolate and drain the appliance before removal, and re-check system pressure after refitting
Mechanical
| Part type | 3Bar Pressure Relief Valve |
|---|
Compliance
| Manufacturer part number (MPN) | 178985 |
|---|---|
| Commodity code | 8481 40 10 00 |
| Alternative numbers | 1375069, 178985, N6751 |
| Make | Model / assembly | Reference | Years | Fitment |
|---|---|---|---|---|
| VAILLANT VAILLANT ECOTEC PLUS 612 VU 126-3-5 | — | — | — | |
| VAILLANT VAILLANT ECOTEC PLUS 612 VU 126-3-5 R1 | — | — | — | |
| VAILLANT VAILLANT ECOTEC PLUS 612 VU 126-5-5 | — | — | — | |
| VAILLANT VAILLANT ECOTEC PLUS 612 VU 126-5-5 R1 | — | — | — | |
| VAILLANT VAILLANT ECOTEC PLUS 612 VU 126-5-5 R2 | — | — | — | |
| VAILLANT VAILLANT ECOTEC PLUS 615 VU 156-3-5 | — | — | — | |
| VAILLANT VAILLANT ECOTEC PLUS 615 VU 156-3-5 R1 | — | — | — | |
| VAILLANT VAILLANT ECOTEC PLUS 615 VU 156-5-5 | — | — | — | |
| VAILLANT VAILLANT ECOTEC PLUS 615 VU 156-5-5 R1 | — | — | — | |
| VAILLANT VAILLANT ECOTEC PLUS 615 VU 156-5-5 R2 | — | — | — |
Showing 10 of 311 compatible appliances.
Fitment listings are a guide, not a guarantee. Plant-room assemblies get modified on site more often than not. Send us the GC number off the data badge and a photo of the existing valve and we will confirm before anything is dispatched.
Documents & drawings
Everything we hold for this part. Where a document exists but we don't hold it, the technical team will source it from the manufacturer — usually the same working day.
manual
VAILLANT appliance manual — VU 126/3-5 (GC 41-044-44), VU 126/3-5 R1 (GC 41-044-44), VU 156/3-5 (GC 41-044-45), VU 156/3-5 R1 (GC 41-044-45), VU 186/3-5 (GC 41-044-46), VU 186/3-5 R1 (GC 41-044-46), VU 246/3-5 (GC 41-044-47), VU 246/3-5 R1 (GC 41-044-47), VU 306/3-5 (GC 41-044-48), VU 306/3-5 R1 (GC 41-044-48), VU 376/3-5 R1 (GC 41-044-49), VUW 246/3-3 R1 (GC 47-044-36), VUW 246/3-3 R2 (GC 47-044-36), VUW 246/3-5 (GC 47-044-31), VUW 246/3-5 R1 (GC 47-044-31), VUW 246/3-5 R3 (GC 47-044-31), VUW 286/3-3 (GC 47-044-30), VUW 286/3-3 R1 (GC 47-044-30), VUW 286/3-3 R2 (GC 47-044-30), VUW 316/3-5 (GC 47-044-32), VUW 316/3-5 R1 (GC 47-044-32), VUW 316/3-5 R3 (GC 47-044-32), VUW 316/3-5 R5 (GC 47-044-32), VUW 376/3-5 (GC 47-044-33), VUW 376/3-5 R1 (GC 47-044-33), ecoTEC PLUS 612 VU 126/3-5 (2005-2005) (GC 41-044-44), ecoTEC PLUS 612 VU 126/3-5 R1 (2005-2006) (GC 41-044-44), ecoTEC PLUS 615 VU 156/3-5 (2005-2005) (GC 41-044-45), ecoTEC PLUS 615 VU 156/3-5 R1 (2005-2006) (GC 41-044-45), ecoTEC PLUS 618 VU 186/3-5 (2005-2005) (GC 41-044-46), ecoTEC PLUS 618 VU 186/3-5 R1 (2005-2006) (GC 41-044-46), ecoTEC PLUS 624 VU 246/3-5 (2005-2006) (GC 41-044-47), ecoTEC PLUS 624 VU 246/3-5 R1 (2005-2006) (GC 41-044-47), ecoTEC PLUS 630 VU 306/3-5 (2005-2005) (GC 41-044-48), ecoTEC PLUS 630 VU 306/3-5 R1 (2005-2006) (GC 41-044-48), ecoTEC PLUS 637 VU 376/3-5 R1 - 2006-2006 (GC 41-044-49), ecoTEC PLUS 824 VUW 246/3-5 (2005-2005) (GC 47-044-31), ecoTEC PLUS 824 VUW 246/3-5 R1 (2005-2006) (GC 47-044-31), ecoTEC PLUS 824 VUW 246/3-5 R3 (2011-2012) (GC 47-044-31), ecoTEC PLUS 831 VUW 316/3-5 (2005-2005) (GC 47-044-32), ecoTEC PLUS 831 VUW 316/3-5 R1 (2005-2006) (GC 47-044-32), ecoTEC PLUS 831 VUW 316/3-5 R3 (2011-2012) (GC 47-044-32), ecoTEC PLUS 831 VUW 316/3-5 R5 (2013 - 2013) (GC 47-044-32), ecoTEC PLUS 837 VUW 376/3-5 (2005-2005) (GC 47-044-33), ecoTEC PLUS 837 VUW 376/3-5 R1 (2005-2006) (GC 47-044-33), ecoTEC PRO 24 VUW 246/3-3 R1 (2005-2006) (GC 47-044-36), ecoTEC PRO 24 VUW 246/3-3 R2 (2008-2012) (GC 47-044-36), ecoTEC PRO 28 VUW 286/3-3 (2005-2006) (GC 47-044-30), ecoTEC PRO 28 VUW 286/3-3 R1 (2005-2006) (GC 47-044-30), ecoTEC PRO 28 VUW 286/3-3 R2 (GC 47-044-30)
manualmanualVAILLANT appliance manual — VU 126/5-5 (GC 41-044-60), VU 126/5-5 R1 (GC 41-044-60), VU 126/5-5 R2 (GC 41-044-60), VU 126/5-5 R4 (GC 41-044-60), VU 156/5-5 (GC 41-044-61), VU 156/5-5 R1 (GC 41-044-61), VU 156/5-5 R2 (GC 41-044-61), VU 156/5-5 R4 (GC 41-044-61), VU 186/5-5 (GC 41-044-62), VU 186/5-5 R1 (GC 41-044-62), VU 186/5-5 R2 (GC 41-044-62), VU 186/5-5 R4 (GC 41-044-62), VU 246/5-5 (GC 41-044-63), VU 246/5-5 R1 (GC 41-044-63), VU 246/5-5 R2 (GC 41-044-63), VU 246/5-5 R4 (GC 41-044-63), VU 306/5-5 (GC 41-044-63), VU 306/5-5 R1 (GC 41-044-64), VU 306/5-5 R2 (GC 41-044-64), VU 306/5-5 R4 (GC 41-044-64), VU 376/5-5 (GC 41-044-65), VU 376/5-5 R1 (GC 41-044-65), VU 376/5-5 R2 (GC 41-044-65), VU 376/5-5 R4 (GC 41-044-65), VUW 246/5-5 (GC 47-044-40), VUW 246/5-5 R1 (GC 47-044-40), VUW 246/5-5 R2 (GC 41-044-63), VUW 246/5-5 R4 (GC 47-044-40), VUW 316/5-5 (GC 47-044-41), VUW 316/5-5 R1 (GC 47-044-41), VUW 316/5-5 R2 (GC 47-044-41), VUW 316/5-5 R4 (GC 47-044-41), VUW 376/5-5 (GC 47-044-42), VUW 376/5-5 R1 (GC 47-044-42), VUW 376/5-5 R2 (GC 47-044-42), VUW 376/5-5 R4 (GC 47-044-42), ecoTEC PLUS 612 VU 126/5-5 (2012-2012) (GC 41-044-60), ecoTEC PLUS 612 VU 126/5-5 R1 (2012-2013) (GC 41-044-60), ecoTEC PLUS 612 VU 126/5-5 R2 (2013-2015) (GC 41-044-60), ecoTEC PLUS 612 VU 126/5-5 R4 (2015-2015) (GC 41-044-60), ecoTEC PLUS 615 VU 156/5-5 (2012-2012) (GC 41-044-61), ecoTEC PLUS 615 VU 156/5-5 R1 (2012-2013) (GC 41-044-61), ecoTEC PLUS 615 VU 156/5-5 R2 (2013-2015) (GC 41-044-61), ecoTEC PLUS 615 VU 156/5-5 R4 (2015-2015) (GC 41-044-61), ecoTEC PLUS 618 VU 186/5-5 (2012-2012) (GC 41-044-62), ecoTEC PLUS 618 VU 186/5-5 R1 (2012-2013) (GC 41-044-62), ecoTEC PLUS 618 VU 186/5-5 R2 (2013-2015) (GC 41-044-62), ecoTEC PLUS 618 VU 186/5-5 R4 (2015-2015) (GC 41-044-62), ecoTEC PLUS 624 VU 246/5-5 (2012-2012) (GC 41-044-63), ecoTEC PLUS 624 VU 246/5-5 R1 (2012-2013) (GC 41-044-63), ecoTEC PLUS 624 VU 246/5-5 R2 (2013-2015) (GC 41-044-63), ecoTEC PLUS 624 VU 246/5-5 R4 (2015-2015) (GC 41-044-63), ecoTEC PLUS 630 VU 306/5-5 (2012-2012) (GC 41-044-63), ecoTEC PLUS 630 VU 306/5-5 R1 (2012-2013) (GC 41-044-64), ecoTEC PLUS 630 VU 306/5-5 R2 (2013-2014) (GC 41-044-64), ecoTEC PLUS 630 VU 306/5-5 R4 (2015-2015) (GC 41-044-64), ecoTEC PLUS 637 VU 376/5-5 (2012-2012) (GC 41-044-65), ecoTEC PLUS 637 VU 376/5-5 R1 (2012-2013) (GC 41-044-65), ecoTEC PLUS 637 VU 376/5-5 R2 (2013-2014) (GC 41-044-65), ecoTEC PLUS 637 VU 376/5-5 R4 (2014-2015) (GC 41-044-65), ecoTEC PLUS 824 VUW 246/5-5 (2012-2012) (GC 47-044-40), ecoTEC PLUS 824 VUW 246/5-5 R1 (2012-2013) (GC 47-044-40), ecoTEC PLUS 824 VUW 246/5-5 R2 (2013-2015) (GC 41-044-63), ecoTEC PLUS 824 VUW 246/5-5 R4 (2015-2015) (GC 47-044-40), ecoTEC PLUS 831 VUW 316/5-5 (2012-2012) (GC 47-044-41), ecoTEC PLUS 831 VUW 316/5-5 R1 (2012-2013) (GC 47-044-41), ecoTEC PLUS 831 VUW 316/5-5 R2 (2013-2015) (GC 47-044-41), ecoTEC PLUS 831 VUW 316/5-5 R4 (2015-2015) (GC 47-044-41), ecoTEC PLUS 837 VUW 376/5-5 (2012-2012) (GC 47-044-42), ecoTEC PLUS 837 VUW 376/5-5 R1 (2012-2013) (GC 47-044-42), ecoTEC PLUS 837 VUW 376/5-5 R2 (2013-2014) (GC 47-044-42), ecoTEC PLUS 837 VUW 376/5-5 R4 (2015-2015) (GC 47-044-42)
manualmanualVAILLANT appliance manual — VU 126/5-5 A R4 (GC 41-044-78), VU 156/5-5 A R4 (GC 41-044-79), VU 186/5-5 A R4 (GC 41-044-80), VU 246/5-5 A R4 (GC 41-044-82), VU 306/5-5 A R4 (GC 41-044-83), VU 376/5-5 A R4 (GC 41-044-85), VUW 256/5-5 R4 (GC 47-044-57), VUW 326/5-5 R4 (GC 47-044-58), VUW 356/5-5 R4 (GC 47-044-53), VUW 386/5-5 R4 (GC 47-044-60), ecoTEC PLUS 612 VU 126/5-5 A R4 (2015) (GC 41-044-78), ecoTEC PLUS 615 VU 156/5-5 A R4 (2015) (GC 41-044-79), ecoTEC PLUS 618 VU 186/5-5 A R4 (2015) (GC 41-044-80), ecoTEC PLUS 624 VU 246/5-5 A R4 (2015) (GC 41-044-82), ecoTEC PLUS 630 VU 306/5-5 A R4 (2015) (GC 41-044-83), ecoTEC PLUS 637 VU 376/5-5 A R4 (2015) (GC 41-044-85), ecoTEC PLUS 825 VUW 256/5-5 R4 (2015) (GC 47-044-57), ecoTEC PLUS 832 VUW 326/5-5 R4 (2015) (GC 47-044-58), ecoTEC PLUS 835 VUW 356/5-5 R4 (2015) (GC 47-044-53), ecoTEC PLUS 838 VUW 386/5-5 R4 (2015) (GC 47-044-60)
manualmanualVAILLANT appliance manual — VU 126/5-5 R6 (GC 41-694-20), VU 156/5-5 R6 (GC 41-694-21), VU 186/5-5 R6 (GC 41-694-22), VU 186/5-5 R6 LPG (GC 41-694-23), VU 246/5-5 R6 (GC 41-694-24), VU 306/5-5 R6 (GC 41-694-25), VU 306/5-5 R6 LPG (GC 41-694-26), VU 386/5-5 R6 (GC 41-694-27), VUW 196/5-5 R6 (GC 47-044-83), VUW 246/5-5 R6 (GC 47-044-84), VUW 246/5-5 R6 LPG (GC 47-044-85), VUW 286/5-5 R6 (GC 47-044-86), VUW 306/5-5 R6 (GC 47-044-82), ecoTEC PLUS 612 VU 126/5-5 R6 (2017) (GC 41-694-20), ecoTEC PLUS 615 VU 156/5-5 R6 (2017) (GC 41-694-21), ecoTEC PLUS 618 VU 186/5-5 R6 (2017) (GC 41-694-22), ecoTEC PLUS 618 VU 186/5-5 R6 LPG (2017) (GC 41-694-23), ecoTEC PLUS 624 VU 246/5-5 R6 (2017) (GC 41-694-24), ecoTEC PLUS 630 VU 306/5-5 R6 (2017) (GC 41-694-25), ecoTEC PLUS 630 VU 306/5-5 R6 LPG (2017) (GC 41-694-26), ecoTEC PLUS 637 VU 386/5-5 R6 (2017) (GC 41-694-27), ecoTEC PLUS 825 VUW 196/5-5 R6 (2017) (GC 47-044-83), ecoTEC PLUS 832 VUW 246/5-5 R6 (2017) (GC 47-044-84), ecoTEC PLUS 832 VUW 246/5-5 R6 LPG (2017) (GC 47-044-85), ecoTEC PLUS 835 VUW 306/5-5 R6 (2017) (GC 47-044-82), ecoTEC PLUS 838 VUW 286/5-5 R6 (2017) (GC 47-044-86)
manualmanualVAILLANT appliance manual — VU 256/5-7 (GC 41-694-02), ecoTEC EXCLUSIVE 627 VU 256/5-7 (2016) (GC 41-694-02)
manualmanualVAILLANT appliance manual — VUI 376/3-5 (GC 47-044-39), ecoTEC 937 VUI 376/3-5 (2006-2012) (GC 47-044-39)
manualmanualVAILLANT appliance manual — VUW 356/5-7 (GC 47-044-66), VUW 436/5-7 (GC 47-044-67), ecoTEC EXCLUSIVE 835 VUW 356/5-7 (2016) (GC 47-044-66), ecoTEC EXCLUSIVE 843 VUW 436/5-7 (2016) (GC 47-044-67)
manualmanualVAILLANT appliance manual — ecoTEC 610 VU 10 CS/1-5 (2023) (GC 41-694-45), ecoTEC 615 VU 15 CS/1-5 (2023) (GC 41-694-46), ecoTEC 620 VU 20 CS/1-5 (2023) (GC 41-694-47), ecoTEC 625 VU 25 CS/1-5 (2023) (GC 41-694-48), ecoTEC 630 VU 30 CS/1-5 (2023) (GC 41-694-49), ecoTEC 635 VU 35 CS/1-5 (2023) (GC 41-694-50)
manualmanualVAILLANT appliance manual — ecoTEC PLUS 940 VUI 30/40 CS/1-5 (2023) (GC 47-044-96)
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