(Cross-posted in other Miele Steam Oven threads) We bought a Miele DGC 6800 XL Combination Steam Oven (non-plumbed) and a few months later on a whim descaled the unit. Right after the descaling process, my Miele steam oven gives me a 'Fault 20' whenever I try to do steam cooking. The regular convection cooking works fine. Expected more from Miele. I wish I had bought something else! It's out of warranty even though we probably used it about 20 times. Now Miele is asking for $150 for a technician to come out and pay an additional $90/hr for labor + $ for parts!

Fortunately, I have a relatively large pantry (vs. a much smaller kitchen). So when I got the Miele Speed oven, I just moved my old Sharp microwave and my ancient, beloved, toaster oven into the pantry. Now, about 8 months after the remodel, I still use the toaster oven for toast, having never even tried to toast in the Miele. And the pantry's microwave gets used to do something quick (like melt butter) while the Miele is pre-heating, or baking, or whatever. Though these things only happen occasionally, its been often enough that I haven't seen my way to tossing out either old oven. The drawback, of course, is that there are 5 ovens in my little kitchen/pantry area, which seems excessive. And I suppose the pantry has less counter space for canned beans or whatever... As for the Miele's combination mode, I've only begun to explore this by using it to reheat things like casseroles -- Alton Brown's "Cauliflower Say Cheese", last night. Master Chef expects me to know how much these things weigh, which is a struggle, but last night's guess turned out just fine. Oh yeah, if you select Defrost mode, the Miele speed oven will heat in the range of 75 to 125 degrees. This setting is useful for cooking "raw" foods at 104. I did think about a steam oven as well, but there really was no way to fit it in there.

75-250 is indeed a pretty large range. But not too unusual to do that. According to https://www.ysi.com/water-hardness that would be somewhere between soft and slightly hard (no particular endorsement; this was just the first site that I found online). I don't think you'd go horribly wrong by telling your oven to treat this as "medium". Worst case, it prompts you to descale the unit more frequently than strictly necessary. That'll waste a little money on supplies. But if in doubt, that's better than wasting money on repairs. I recommend you buy the descaling tabs in bulk. They regularly show up on Amazon and other online services. And they definitely get cheaper if you buy a bigger package. You'll need two per descale cycle. I usually need to do so every six to nine months. But that might not be the same for you. We use the steam oven very frequently, but we have very soft water. Also, you absolutely want to make sure you have tabs on hand, when the unit needs it. You don't want to find yourself in a situation where you can't use the oven for a few days while waiting for supplies.

RE: Miele vs Wolf. We have a vacation home with Miele speed oven (2010)(combo of microwave and convection with broiler), 30" convection oven, and induction cooktop. We use the speed oven for everything except large meats due to its speed of heating up with the 'rapid heat' feature, but find it inconvenient to not have a microwave available if we are using the oven. But, to simply microwave requires about 5 or 6 steps on the digital panel, a big PITA. And, guests cannot figure out how to use the German minimalist controls for the induction and the microwave. Form over function! So, with our new home in Seattle (2015) we used all Wolf this time. We use the steam convection oven daily, and we don't clean it much. I did a side by side at Albert Lee showroom putting muffins and almond croissants into the Wolf and the Miele, both cold, set both to steam convection at about 360ºF. The Wolf was easier to set (even the showroom person had difficulty navigating the Miele minimalist digital screen). In about 5 minutes the Wolf produced internally moist, externally browned and crispy croissants, the Miele was not yet flaky or crisp on the outside. So, that made my decision for me! Does anyone know if the baking soda/peroxide past cleaning regimen damages the Wolf CSO? Thanks all for the entries. I am late in responding, having just read the thread.