If the steam tstat isn't connected to the boiler you've got a dangerous machine.
- quoting an "expert on the harmon gaggia group"
"If the steam tstat isn't connected to the boiler you've got a dangerous machine. The tstat must be in contact with the boiler for it to know when to open the circuit. If it's not in contact you'll have a runaway boiler if the steam switch is ever flipped on.
You should either fix the broken tstat (piece of cake) or disconnect the leads to it so the circuit is always open."
BIG NEWS! if you disconnect the wires to the steam thermostat, the machine will NOT even heat. Just amazing what passes for advice out there.
In depth: The thermostats on gaggia are especially fragile as they are crimped at the bottom of the part, not held in a wrap-around clamp as with other machines. They get MORE fragile as they age from all the heat. Be very careful when pulling off wires from the thermostat, since if it separates from the brass base it will be