What is a Tundish? & How does it work?

If you’ve never heard of a tundish, you’re probably wondering what on earth it is.

Is it a dish, or is it something from the esoteric world?

No, a tundish has everything to do with a water heating system! If you’re looking for a device to determine if your water heater is releasing water due to excess water pressure, a tundish is what you need!

If we think about what a tundish physically is, it is a cone-shaped piece of plastic found between two pieces of pipe. The tundish is fitted close to your boiler’s pressure release valve of unvented hot water systems, which have a penchant for building up excessive water pressure that eventually damages the boiler.

Suppose you have an unvented hot water system. In that case, you undoubtedly know that they offer many advantages over traditional heating systems, so finding a solution for the excess pressure build-up is a preferred route to replacing the existing boiler.

Unvented hot water systems have been growing in popularity. First, they are connected directly to the house’s mains, so there isn’t a need for a cold water tank to bring the system cold water from the mains. Because there is no need for the cold water tank, you get to save on space.

Secondly, these systems provide high water pressure, especially if you simultaneously use many appliances and taps. Because of this high pressure, the tundish will require a pressure relief valve.

A tundish works in conjunction with a pressure release valve. The pressure release valve is installed on the unvented hot water system, which ensures that water is drained from the system if the pressure peaks.

The tundish is installed to alert people that the pressure is rising and draining water. Then, you can use the information to report the problem to an engineer who is GSR (Gas Safe Registered).

What Does a Tundish Do & How?

The essential role of a tundish is to ensure that there’s no cross-contamination between the overflow pipe and the drainage pipe on the boiler.

Why is this necessary? Because if unsanitary water enters the system from the drainpipe, it could end up contaminating your water supply. The tundish must therefore be correctly installed to stop this from happening.

But that’s not the only role of the tundish. It is also tasked with ensuring there is an air gap so that you can see if water is flowing from the installed pressure release valve.

Is it Okay if a Tundish Drips?

Your tundish should not drip if everything is in good operating order. If the tundish is dripping, it is time to call out a qualified boiler engineer, as it’s a red flag that there’s a problem with the pressure release valve. It could also be a sign that the water pressure in the system has gone beyond a normal point.

Is a Qualified Engineer Essential for Tundish Installation?

It’s important to leave the installation of a tundish up to a qualified engineer. This is because there are strict regulations regarding the installation and adjustment of a boiler system and components, so if you do it incorrectly, your system could be considered illegal.

Of course, as is the case with most things, there are various regulations in place regarding a tundish installation.

For starters, the UK government GB building regulation states that unvented hot water systems must have left at least a 50 cm distance between the pressure release valve and the tundish. In addition, the tundish must be placed in a visible position so that you can easily see if the system is dripping any water.

The pressure release valve should also be spaced at least 15 mm from the discharge pipe with a distance of 2.2 mm from the pipe transferring water outside the property. Your discharge pipe will need to handle very hot temperatures, so it should consist of metal or another material that performs well in hot environments.

How to Check the Tundish

You will find checking the tundish very simple. There is no need to go for training or even use any tools. First, locate the tundish on your system. If you find the pressure relief valve, simply follow the line to locate the tundish.

Once located, check the device for signs of water. If you see water flowing into the tundish, you immediately know that your pressure relief valve is leaking and there is a fault with the system.

Several problems can crop up with the boiler. The most common problem is excessive pressure in the system. This is often easily solved by simply adjusting the pressure.

An engineer must do this because there’s an immense danger when working with such a pressurized system. Another common problem is that you have a faulty pressure relief valve.

A pressure relief valve will only leak if there’s too much pressure, so if it’s leaking when there’s no pressure, it will fail when it’s genuinely needed. Therefore, you should replace a faulty pressure relief valve as soon as it is noticed.

Regular maintenance should be paramount in your mind when it comes to using a tundish correctly. Your tundish will not send a mobile phone alert or send off an alarm when it’s doing its job, so it’s your responsibility to ensure that you regularly check the system.

Make this part of your basic home maintenance routine. If you see water flowing through the tundish, get hold of your chosen qualified engineer to have the problem rectified as soon as possible.

What is a Tundish? Final Thoughts

The tundish, which is installed on overflow pipes, can serve as a viable warning system for over-pressured heating systems.

If the tundish is dripping water, you should immediately call a qualified professional to inspect the unit. When you install a tundish, it must also meet the G3 Building Regulations.

With a tundish correctly installed, you can continue enjoying the benefits of an unvented heating system!

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