Espresso Machines; Stainless Steel Boilers

At 1st-line, we always look at trends, many of which are created by marketing tactics as well as needs for problem resolution. However, I must admit 1st-line doesn't always jump on the bandwagon, immediately.

For example, one previous trend was magnetic floats in water reservoirs. Just like a water tank switch would fail when water was spilled on it, we knew magnetic floats would not float forever or worse, magnetic floats in water reservoirs would stick near the top and the machine would think it would have water, when the tank was actually empty. If the boiler called for water, this could lead to a dry boiler causing an expensive heating element repair. This is how we think things through before jumping on the bandwagon from a practical perspective....

Now, back on topic....stainless steel boilers have been the trend recently. One reason is from a health perspective, but the second for lessening limescale build up. However, after speaking to a potential client, stainless steel may not be the best option. The reason is that stainless steel may start to rust. Here is an article I found.

In the past, I have heard of customers getting black water out of their machines with stainless boilers. I believe this is the rust that is occurring. When I inquired about it, the boilers typically needed to be replaced. AT this point, I am unsure how the internals of a boiler can be passivated.

The other issue I believe also happens is that limescale does slide off the stainless boilers and culminates at the bottom of the boiler. Hence the boiler does need to be drained at some point.

Although I am not a metalurgist, I would invite you to this thread to learn more.