What does this little add-on options do? Well hopefully I’ll be able to explain, please do remember though that this is in my own words and I don’t refer to manuals and the like unless I’m quoting numbers.
The function of the temperature sensor is to stop hot water coming out of the outlet connected to the UV unit. If water is left in the chamber and exposed to lamp for an extended period of time, the water will heat up. This is more an issue for the high power lamps that will do this quite effectively. So for units that go for long periods of no flow, we would always recommend the addition of a temperature sensor and dump valve or TSD. These keep track of the temperature and once it gets to a certain level the dump valve will open and a certain amount of water will be let out into a designated area. Once cooler water has filled the chamber, the temperature reading will be lower and the dump valve will shut off again. This will continue so if it heats up again a second dump will occur and so on. These can be essential in quite a few environments such as pharma and ones where human contact is likely, but they can be useful in many more. The problem with having hot water in your system is that if it does damage anything, it’s usually done too late to do anything about it and it’s difficult to identify it as a cause.