Reliability of Fernox Express Inhibitor Test Strips

[sharpener]

Because the price of the official pots of 50 of these test strips is so high I bought a packet of five for £6-99 from ebay, arrived without instructions or colour matching chart.

 

The online instructions say read the strip within 10 seconds but they showed little colour by then. However a dark brown shade developed after about 30 secs. Google AI says this means they are time-expired or contaminated.

 

The system was power flushed before the HP was fitted in 2024 and Adey inhibitor and biocide added afterwards. I am not particularly concerned but both years since, the Vaillant service technicians have said that they do not test inhibitor strength.

 

Should I be worried? Should I return them to ebay and claim a refund? Are THESE PHP tests at £3 per test any better? Is there an alternative?

 

TIA.

[SimonD]

I have the Adey kit and use it quite a lot actually - works well and is reliable. When I bought my kit which comes with the charts - 1 per test strip, the big pack of test strips were out of date so I emailed my supplier and they arranged replacement directly from Adey. Once I ran out of in date ones and used the out of date ones and they were still fine.  

 

Technically it's now a service requirement on most if not all gas boilers and heat pumps. I'm sometimes surprised when systems I installed and dosed correctly show low levels of inhibitor, but it happens even after just a year sometimes.

I'm not sure how often most systems get tested. I went through a phase of testing every new gas boiler I serviced and ran a good top-up business for a while until I stopped taking on new customers. As for Vaillant technicians not testing, well that's pretty much a given, but just wait until there's a warranty claim - as customers of mine who became my customers learned when their hex started leaking on a nearly new Glow-worm and the installer wasn't interested. Vaillant/Glow-worm visited and told them they wouldn't touch it unless they could provide a certificate that the system had been flushed to BS standards and that inhibitor had been added (even thought the system was leaking) - queue them calling me.

[sharpener]

2 hours ago, SimonD said:

I have the Adey kit and use it quite a lot actually - works well and is reliable. When I bought my kit which comes with the charts - 1 per test strip, the big pack of test strips were out of date so I emailed my supplier and they arranged replacement directly from Adey. Once I ran out of in date ones and used the out of date ones and they were still fine.  

 

Technically it's now a service requirement on most if not all gas boilers and heat pumps. I'm sometimes surprised when systems I installed and dosed correctly show low levels of inhibitor, but it happens even after just a year sometimes.

 

Thanks for that. AFAICS the Adey tests aren't as widely available in small quantities but with unauthorised break-bulk Fernox distributors I guess you get what you get. Ebay will not yet let me give negative feedback as there is a 7 day embargo.

 

The Vaillant-approved installers did a full Adey 3-part water test (pH, turbidity, inhibitor) on completion but don't seem to be interested in routine servicing. As you say, Vaillant are notorious for finding reasons for invalidating your warranty so it is doubly irritating their technicians do not touch anything not of their supply incl. water quality.

 

Would still like to hear more about what other ppl do in these circumstances!