Water Heater Accessories

Get everything you need for your water heater with our range of water heater accessories. Whether it’s an expansion vessel or a discharge tundish, we’ve got you covered with all items in stock and with free delivery. What more could you want?

Expansion vessels are perfect for when water expansion cannot be accommodated within your pipework. Ours have been designed for use with under-sink hot water heaters specifically.

A discharge tundish is recommended in every installation of a stored water heather. They allow you to observe if water is being discharged from the unit and pressure relief valve.

When it comes to water heater accessories, having the right tools for the job makes all the difference. Think of expansion vessels as the hidden but ultimately most important part of your plumbing setup, stepping in to handle water expansion exactly when you need it. No more worrying about extra pressure wreaking havoc on your pipes – these vessels take the stress off (literally), keeping your system running smoothly.

And then there’s the discharge tundish, the watchful guardian of your water heater. It’s not just a practical must-have; it’s a peace-of-mind provider. With a tundish installed, you can easily monitor your system, ensuring any discharge from the pressure relief valve doesn’t go unnoticed. It’s like having a built-in alert system for your water heater – no guessing games, just clear visibility.

With all items in stock and free delivery, we’ve made it easy to get exactly what you need without the hassle. Whether you’re a pro plumber or a DIY enthusiast, our range of water heater accessories is here to make your installations safer, smarter, and more efficient.

So, why wait? Equip your water heater with the best, and enjoy a system that’s ready to handle the heat – literally and figuratively. Explore the range today and get in touch if you’ve got any questions.

Triton Kit A – 2L Expansion Vessel & Non-Return Valve

£62.99 inc
VAT

Save £21.01 | Was £84.00

Triton Kit C – Discharge Tundish

£21.99 inc
VAT

Save £12.01 | Was £34.00

Do I need an expansion vessel for my under-sink hot water heater?

You need an expansion vessel when the thermal expansion from heating cannot be absorbed by your pipework. Under-sink hot water heaters commonly create that extra pressure, so a purpose-designed vessel for under-sink units will take the stress off your pipes and valves. If you notice the pressure relief valve discharging or pressure spikes when the heater fires, an expansion vessel will stop those events. A compact 2 litre vessel is often the right fit for small, under-sink heaters.

How do I know what size expansion vessel to buy?

A 2 litre vessel, like the Triton Kit A, is aimed at compact under-sink heaters and suits many small installations. Larger stored heaters will need a larger vessel matched to the heater's water capacity and system pressure, so check the heater specification to confirm. If you have a small point-of-use unit under a sink, a 2 litre vessel is a practical, commonly used option.

What is a discharge tundish and why is it recommended for stored water heaters?

A discharge tundish is a visible funnel or chamber fitted to the outlet of the pressure relief valve so you can see any discharge. Because it makes leaks and valve activations obvious, it is recommended for every stored water heater to help you spot problems early. if the relief valve opens you'll see water in the tundish rather than having it drain unseen behind your cupboard or walls.

Can I use the under-sink expansion vessel with my existing plumbing?

The expansion vessels offered here are designed specifically for under-sink hot water heaters and work best in systems where the pipework cannot absorb expansion. If your current plumbing already provides an expansion path or the heater is a larger stored unit, a different vessel size or type will be more appropriate. For a typical retrofit to a small under-sink heater, the compact 2 litre option is a straightforward match.

What does the non-return valve in Triton Kit A do and is it necessary?

The non-return valve prevents water from flowing back into the cold supply from your water heater, protecting the mains and avoiding cross-flow. On under-sink heaters, it helps keep hot water where it belongs and can prevent pressure-related issues in the cold feed. If your set-up includes a small point-of-use heater feeding a mixer tap, the non-return valve is a simple way to maintain correct flow direction and system safety.