Is there a problem with Fernox products?

[Aulus]

Has anyone come accross this?

In January I cleaned flushed & protected my CH system with Fernox DS40, Protector, & Silencer. Later I notice the DHW isnt coming on. After much grief Ive nailed the fault to the pressure differential switch in my Vailllant - there's a thick oily/greasy goo dripping from it!

The same happened a few years ago but I didnt link it to the Fernox, but I cant see it can be anything else!

IS this a known problem that I wasnt aware of?

 

[Rob]

I'd put it down to poor flushing!

 

[DP]

A leak or a weep will allow the chemicals to dry out in described manner.

Failure of diverter may not be related to chemicals. As mentioned before, poor flushing might be an issue