I have buildings that have three or four of these used as water heaters. I realize this is being used to heat the building, but lets just say, if you look at it closely, it will have provisions to use it as a domestic water heater.
The operator rules typically come to a head when there is a danger of issues if the system is not monitored at all times, this would be virtually any high pressure steam boiler or boiler with "manual controls".
Other than the boiler you pictured being relatively small, it heats water.
Also, I would be willing to bet that if you look at the piping diagrams in the installation and maintenance manual, you would not see that piping as an example... I see three mistakes and that's just from a quick glance from a picture...