What is a tundish? – How do they work and what do they do?
Tundishes are used for an unvented hot-water system and sealed boilers. They allow water to flow from a valve to a downstream pipeline and the user can see the water moving through the valve via an open-sided design.
Tundishes are devices that are placed near the pressure release valve. They allow people to check if the water has escaped from the heating system because of excessive water pressure. While unvented hot water systems offer many benefits over traditional heating system options, excessive water pressure can cause damage to a boiler and heat exchanger if it is not checked.
It usually consists of an inlet that is connected to the tundish body. It is usually constructed with two arms and has an open side. The outlet connects to the downstream overflow pipe. This waste pipe was normally terminated at the outside of the building, up until the advent dry trap tundishes.
The pressure release valve outlet allows water to drain from the system in the event of the hot water or hot temperatures creating too much high pressure or a boiler overheating.
What does a tundish do?
A PRV releases steam or water from a hot-water cylinder when the pressure gets too high. The water should be properly drained into the pipe. To check if your water tank is having problems, you will need to fit a tundish to the drain pipe.
A clear window allows you to see if water is leaving the pipe. This could indicate a problem with the expansion vessel or PRV. This could indicate a problem with either the expansion vessel or the PRV.
A tundish can also provide an air gap. The air gap is a break between two pipes. It is used to drain any water from the appliance. The high pressure could cause water to be sucked back into a hot water tank without an air break.
This is prevented by an air break and ensures that waste water drains properly. This prevents cross-contamination, especially if the overflow pipe is connected with a drain or sewer pipe. if your getting a new boiler these are not usually included in the total new boiler costs.
How do I check my tundish?
It is very easy to check your tundish. Locate the tundish by following the line. It is often easier to locate the pressure relief valve.
You should inspect the tundish for any signs of water. If water is seen in the tundish, it is likely that the pressure relief valve has sprung a leak. This information is crucial because it indicates that the system is having problems. There could be many types of problems.
Your unvented cylinder pressure may be too high. This is the easiest problem to fix for someone who knows what they are doing. It could be a simple problem that needs to be corrected. However we recommend that you get a Gas Safe registered heating engineer to perform a proper installation as if you do it yourself, the system is pressured, and making a mistake can be deadly.
Your pressure relief valve may be faulty. This is the second possible problem. The valve can only be opened if the system is over-pressurized. The valve could fail completely if it leaks or the pressure is too low therefore it must be replaced.
What regulations apply to a tundish in a gas boiler?
The tundish must be installed by a qualified heating engineer who will follow the applicable building regulations. The Building Regulation G3 Approved documents provide detailed information about the installation and positioning of the tundish.
The tundish should not be more than 600 m from the PRV. The tundish’s minimum straight drop should not exceed 300mm. This means that the tube that leaves the tundish must be straight for at most 300 mm before it bends or turns in any other direction.
The tundish should be vertically located and not more than 500mm horizontally from any valve which discharges to it. The tundish must be visible from the ground. It is there to help you identify any leaks but not become a danger.
The discharge pipe that runs out of a tundish must also be regulated. This pipe should be made from metal and should be longer than the inlet.
