The Vaillant 178973 DHW Plate Heat Exchanger is a genuine Vaillant replacement part for ecoTEC Plus combi boilers. This 20-plate secondary heat exchanger transfers heat from the boiler’s heating circuit to your domestic hot water, giving fast and steady hot water at the taps.
Over time, limescale and sludge can block the plates. This leads to poor hot water flow, temperatures that go hot and cold, noisy operation or leaks. Replacing the plate heat exchanger restores full hot water performance.
Key Features
- Genuine Vaillant part – Part No. 178973
- 20-plate design for efficient heat transfer
- Supplied with 4 O-rings and 4 fixing screws
- Direct replacement – no modifications needed
- 1 year manufacturer guarantee
Compatible Boilers
- Vaillant ecoTEC Plus 824 (VUW 246/3-5 R1)
- Vaillant ecoTEC Plus 831 (VUW 316/3-5 R1)
- Vaillant ecoTEC Plus 800 series & VUW models (2005–2010)
Please check your boiler model or the old part number before ordering. If you are unsure, contact us and we will confirm the right part for you.
Specifications
| Brand | Vaillant |
| Part Number | 178973 |
| Type | DHW (Secondary) Plate Heat Exchanger |
| Plates | 20 |
| Included | Heat exchanger, 4 x O-rings, 4 x screws |
| Guarantee | 1 year manufacturer guarantee |
Installation
This part must be fitted by a Gas Safe registered engineer.





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