What is a Tundish?

All unvented water heaters and cylinders have a failsafe valve, known as a pressure relief valve, to protect the tank from excessive pressure build-up during the water heating process. This valve needs to be able to expel water or steam via a pipe attached to the valve, and ideally, this needs to be through an outside wall to a drain via a tundish.

What is a Tundish? How Does it Work?

It is a device placed close to the pressure release/relief valve that allows people to see if water has escaped the system due to excessive water pressure. Traditionally used in brewing, a modern tundish performs a few tasks in a pressurised or unvented water heating system. They offer a window into the overflow water line route, allowing you to visually detect a set of issues that could occur in your expansion relief system or overflow drainage. The tundish creates a visual indicator (dripping water from it) that helps the repairer diagnose otherwise hard-to-spot issues. Secondly, they help inhibit any potential contamination between relief pipes and overflow pipes, ensuring that even smaller compromises don't add up to a cylinder or water heater intaking or returning contaminated waters into your outlets.

What's a Hotun? Dry-Trap? What's That?

A reason you previously wouldn’t have had this arrangement installed inside a property would be the issue of drain smell coming through the tundish. Until recently, that is. There is now a way of connecting this pressure relief valve to an internal waste pipe, thanks to a fairly new product: the Hotun Dry Trap Tundish.

"The solution is an open-sided tundish trap with a non-return valve. The hotun dry trap tundish does what a standard tundish does plus stops smells, odours and foul gasses from entering the building via the drain connection." - Hotun

So the benefits of the Hotun include:

 

Small-sized and ideal for use in small spaces

Users are able to visibly see the PVR discharge

Ability to deal with trickle and full flow discharge conditions

Hotun & Hotun SF 15 – 22 has a flow capacity of up to 16 litres/minute

Hotun hiflo & Hotun hiflo SF 15 – 32 has a flow capacity of up to 25 litres/minute

The current largest unit, Hotun XLSF 22 – 32 has a flow capacity of 40Litres/minute

Compatible with any unvented hot water heater or sealed system boiler PRV discharge pipe

Removes the risk of wholesome water supply contamination

Eliminates the need for any drilling work through external walls

Standard plumbing connections are used on the inlet and outlet

Conclusion

Since the initial launching of their Dry Trap Tundish, Hotnu have managed to change the game for installers, where this method has become preferable for installers nationwide. Modern unvented water heaters such as the Megaflo range often come pre-equipped with Tundish as part of their installation guidance and accessories. For more information, or to discern which Tundish you require, give us a call on 01934 253600