The DEL 301 in our big 8x8ft hot tub just died. Non-repairable unit, apparently the UV lamp shattered, blew a fuse in the spa pack, need to replace the whole ozonator.
I'm looking around for relatively low maintenance replacement, but it looks like ozonators are just all-around high maintenance devices. The more I research, the more annoyed I get.
Corona discharge ozonators apparently produce more ozone over the life of the generator, but apparently typically must be replaced or rebuilt after about 2 years. Also if there's any moisture in the air, it apparently contributes to nitric oxide formation, which converts to nitric acid on contact with water. And since the ozonator is inhaling air from around a hot steamy hot tub, the likelihood of moisture is rather high.
Ultraviolet ozonators apparently don't produce nitric oxide, but the ozone output is lower than with corona discharge, and the UV slowly degrades the lamps due to a process called solarization that actually impedes UV output as the lamp ages. This appears as a brownish coloring of the lamp, and eventually the UV lamp just becomes a space heater. It can apparently fail to function, even before the UV lamp actually stops lighting up.
UV Efficiency Lost to Solarization
UV efficiency is lost because of the cumulative effect of solarization of the quartz UV lamps themselves. Solarization is the photochemical ageing process that naturally occurs in the presence of high ultraviolet radiation over time. While the above curve shows radiation being produced past 9500 hours, mercury vapor lamps become unreliable after about 8,000 hours of operation. UV lamps must be replaced on a routine basis to prevent a sterilizer from becoming just an expensive piece of pipe. Because lamp output degrades over its life it is important to size a system for sufficient performance at the End-Of-Lamp life (EOLL). Doing so will insure that throughout the life of the lamp you will actually achieve a higher UV dose.
(So after only about 1000 hrs of operation, output is down 20%, and a "50mg" UV ozonator is now a 40mg ozonator...)
Apparently some ozonators are supposed to be periodically disassembled to wipe dust off the lamp/CD chip.. did it occur to these people to simply put an air filter on the ozonator inlet?
DEL has the MCD-50 which can be "rebuilt" every couple years, but the rebuild seems like a joke, as it consists of about 75% of the parts of the entire unit, including the power supply module. The only original parts retained after a rebuild are apparently the outer plastic shell and the power cord...
It seems like ozonators are a hole that you have to keep throwing money into, to just keep them working properly.