UV sensors – Do I need one?

We’ve seen environment agencies increasingly recommending that UV sensors are installed with UV units. I’ll quickly take you through what a UV sensor does and the pros and cons of having one on your UV unit. Bear in mind that this is purely subjective and written from my own experience. However, I have personally advised several environmental health departments on what is considered ‘best practice’ in the industry (and they haven’t rang me back moaning about my advice yet).

What is a UV sensor

A UV sensor shows how much of the UV light is getting through the water going through your UV unit.  For example, if your UV sensor shows a reading of 90% then 10% of the light from the UV lamp is being blocked (or diffracted) by bits and pieces in your water. Tap water would show a reading of about 95% for reference. There are several ways to improve your water quality but that isn’t for this post.

Pros of a UV sensor

• A UV sensor will give you a real time reading of the effectiveness of your UV unit.
• Peace of mind. UV units don’t actually show you that they’re doing the job they’re installed for by default. You rely on us having done our job right in the first place.
• The environment agency will love you for it. Having proof that the system is doing what it’s meant to do is a joy for any inspector. That’s why they recommend them in the first place.

Cons of a UV sensor

• It’s only useful if you have someone that is going to regularly check it, and probably keep a record of what it says. UV units are designed to alert you if anything goes wrong as standard, either with a audible or visual alarm.
• There’s more to go wrong. As an electrical component there is always a chance that something could potentially go wrong with it no matter how robust they are.
• Expensive. It’s not a big deal on larger units (in regards to the proportion of the total cost) but  a half decent UV sensor starts at around £200. Smaller domestic UV systems start at around the same price.

So in summary, if you’ve been recommended to install a UV sensor and you don’t mind the extra outlay then it’s never going to do you any harm. The chances are that you more than likely don’t need it, especially if it’s for a domestic application (it’s different for commercial) and you’re going to check back with the unit once a year when the lamp is due to be changed. Just like you usually would. That said, if you think you might need a UV sensor, give us a call. We’ll always be honest and impartial as to whether you need one or not.