Vaillant Plate Heat Exchanger DHW 20 Plate 178973

The Vaillant 178973 is a plate heat exchanger designed for domestic hot water production in Vaillant Ecotec Plus combi boilers. It transfers heat from the primary circuit to the domestic hot water supply, allowing the boiler to deliver instant hot water on demand. This component is a Vaillant spare part, identified by part number 178973 and alternative number 1376534. The plate heat exchanger is a compact, brazed unit that keeps the heating water and domestic hot water separate, preventing cross-contamination. It is a critical component in combi boilers, and when it becomes scaled or blocked, hot water performance drops.

• Domestic hot water runs lukewarm or fluctuates in temperature, often worse at higher flow rates.
• Reduced hot water flow rate at taps, sometimes with a noticeable drop in pressure.
• Boiler displays a fault code related to DHW or overheating.
• Visible leaks or weeping from the plate heat exchanger gaskets or connections.
• Limescale or debris build-up causing poor heat transfer and increased boiler cycling.

• Check the GC number on your appliance's data badge to confirm compatibility.
• This part is fitted to a gas appliance; installation must be carried out by a Gas Safe registered engineer.
• Verify the part number 178973 or alternative 1376534 matches your existing component.
• Check for any signs of scale or debris in the primary circuit before fitting.