When your UV lamp is replaced it is recommended that the quartz sleeve that holds the lamp is removed and cleaned and the seals on this are replaced. So for those who are not sure of the setup here a brief explanation is as follows. There is a stainless steel chamber on most UV systems. Within this chamber which is either horizontal or vertical in a system contains a quartz sleeve which runs the length of the chamber internally. The quartz sleeve is a test tube, sealed at one end and open at the other.

 Next to the filter elements in water systems that need replacement is the UV lamps replacement. Generally UV lamps require replacement annually. This is because they degrade. At the start of their life when they are new UV lamps (depending on quality) emit UV intensity of around 100%. As they get older this intensity reduces to the point where the water passing through the UV chamber is not getting enough exposure to sterilise any bacteria that may be present in the water.