Hi everyone,

I have happily owned a BZ10 now for some 2.5 years. So far I have not descaled my machine. Instead I have consistently used ion exchange cartridges that I replace every 3 months, which is the retailer's recommendation for an average home use regime if the water has a hardness of 4 - 8 degr. DH (equivalent to 4.2 - 8.3 grains of CaCo3/US gallon). In my town the water hardness is about 7.5 grains/gal.
Whether or not the water filtering takes away the need to descale seems to be up for debate. I often use the hot water tap for making tea. On one hand this should inhibit or at least further reduce the tendency of scale build-up. On the other hand, it causes a larger water turn-over and maybe early saturation of the cartridges that goes unnoticed. So far I have not noticed anything like the auto-fill or p-stat acting funny or a drop in brew temperature, which I reckon are tell-tale signs of scale build-up.

I am wondering whether this is enough to conclude that descaling is not really necessary at this usage pattern or are there any other (early) tell-tale signs I should be aware of without having to disassemble the boiler ? (Since it is not an E61 machine, Eric Svenson's recommendation to check the mushroom for scale does not apply.)

Any advice would be highly appreciated.

I would test the water coming out of the system. It could just be scaling slowly, but in 50 or 100 years have very serious problems.