(Cross-posted in other Miele Steam Oven threads) We bought a Miele DGC 6800 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. Wish I had 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!

Drain line from steam oven would be mostly warm water. There may be a bit of food scrap in small pieces. I often see bread crumbs when I run rinsing program on the oven floor. Generally these shouldn't be any harmful for plant. The oven requires descaling every now and then. And that's probably your main consideration where it should drain to. Another point, is that if there is no odor trap, would there be any crawlies trying to get into your oven?

First of, congratulations on your good deals for these three units. They will serve you well. For ventilation and wiring purpose, you will need a gap at the back of the shelf behind unit. For combi steam oven, this is where the oven sucks in the air in. It will vent warm air to the front underneath fascia. So following diagram #1 looks fine. For the sentence "The cabinet housing must not have a back panel fitted behind the installation niche", this must be from a newer manual of the combi steam oven. For example, see newer 6805 manual vs older 6805 manual. In a version that I have it uses "Make sure there is no back wall behind the building-in recess" which means that there should not be a cabinet back wall right at the cut out area. See picture for air intake in combi steam manual in installation section. In terms of installation each is 18" tall, just need to be arranged such that coffee machine is not too tall, and speed oven not too low. Perhaps somewhere where the bottom of the combi steam oven is a little bit below bench top level. A combi venting warm air at the front is not an issue for comfort. I have only combi steam oven in my kitchen and its bottom is at the bench top level which is very convenience, but that would put coffee machine a little too high up, if it is going to be on top. Here is an image from mile-vs-wolf-steam-oven thread. Found a funny image on the web of Miele ovens, noted the coffee machine location.

My Miele SO allows you to set the micro timer up to 10 mins per operation. That should be sufficient for most needs. I had a very intermittent issue with the micro function. (3 times in 16 months). It only happened to me once in month 16 where I saw the error message the other two times my daughter was using it. The error resulted in the oven restarting and all was good so not a show stopper as far as function. I called MIele and asked what the error was. They told me it was an expensive repair and since was I "slightly" out of warranty (1 year - did not purchase the 5) they would repair it free as a one time goodwill which they did. I was very pleased at the service. I use the oven almost daily as a small oven and it works as well as my combi steam in the non steam modes. It is a great small oven.