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What is a Tundish? Everything you need to know about what a Tundish is and how to check it

Water heating technology has evolved a great deal over the last century or so. We’ve gone from having to manually heat water over an open fire and carrying it in buckets to being able to open the tap and enjoy immediate access to hot water for all our washing needs.

However, if you’re like most people, you know only a little bit about the technology that allows this to happen. Your water cylinder’s operation is likely as little understood as how satellites work with GPS systems. One of the least understood pieces of your water cylinder is called the tundish.

Knowing what a tundish is, what it does, and how to check it are important considerations for homeowners today.

What Is a Tundish?

While it might sound like some sort of pan or dish that is placed under your water cylinder, a tundish is actually something else altogether. It looks a bit like a plastic cup attached to piping on your cylinder. You’ll find it just off the pressure relieve valve and above the discharge piping.


What Does a Tundish Do?

A tundish performs two principle tasks. First, and most importantly, it serves to prevent any sort of cross contamination between an overflow pipe and a drain pipe. It serves as an air gap and provides a visible window into the overflow system, as well. Without the tundish in place, you would not be able to see any water flowing from the pressure relief valve to the overflow drain.

How Do I Check My Tundish?

Checking your tundish is actually very simple and requires no tools or even special training. Simply locate the tundish (often easier to do by locating the pressure relief valve and then following the line). Check the tundish for signs of water. If there is water flowing into the tundish, then you know that your pressure relief valve is leaking. This bit of information is very important because it tells you that there is a problem with the system itself. Of course, there could be more than one type of problem.

The first and simplest problem to rectify is that your unvented cylinder pressure is too high. This might be nothing more than a need to adjust the pressure in the system, although we do not recommend doing this yourself, as the system is pressurised, and a mistake could be dangerous.

The second potential problem (and one of the more common issues) is that your pressure relief valve is actually bad. This valve is only designed to open in the event that the system becomes over pressurised. If it is leaking and the system is not over pressured, then the valve is in danger of failing completely. It will need to be replaced.

Checking your tundish regularly should be part of your basic home maintenance. If you see water in the tundish, it is important to get in touch with Easy Flow immediately as it indicates either an over pressure situation or a failing pressure relief valve.

If you would like a qualified EasyFlow engineer to come and check any problems with your Tundish, call us on 0161 941 5571. Please check our LOCATION tab to see if we cover your area.