Water Quality Blog

Using my experience as an Electrician for over 40 years this I hope this will explain simply the life of UV lamps operation.

UV lamps dislike two things:

1. Being turned off and on (switching)
2. Heat

We are always asked “Why UV lamps (as in those used for whole house UV water filtration) can’t be turned on every time a tap in the house is used?

 When the lamp is turned on, it takes about 5 seconds to strike and another 20 seconds to get to full operating output of UVC. In this time the pump pushes through around 30+ liters of contaminated water into the house water system. Not an ideal situation if this happens 30 to 50 times a day!

If you prefer to have the lamp only operating when needed, a Water Guard NZ Ltd timer module is available that holds the pump back from operating until the UV system is fully operational then allows the pump to operate. This ensures that any and all water flow is fully treated.

There is some stress placed on a fluorescent light every time it starts up.

If the lamp is installed where it is frequently switched on and off, it will age rapidly. Under extreme conditions, its lifespan can be dramatically reduced.  Each start cycle slightly erodes the electron-emitting surface of the cathodes (the heaters at each end of the lamp); when all the emission material is gone, the lamp cannot start.

This on and off is called Switching, Lamps can handle being switched up to 4 times a day and operate to the stated lamp life of the manufacturer, However if switched, say 40 times a day, the lamp could have a life of less than 2 months.

A UV lamp does not have the usual glowing filament of an incandescent bulb, instead, contains a mercury vapor that gives off ultraviolet light when ionized.

When a UV or fluorescent lamp is operating 24/7 it is very important that the operating temperature is kept at an optimum temperature around the 40 to 50 degree C mark.