Mambo T-stat

[John Achin]

My neighbor asked me what this control box was for, her home has a hot water boiler with thermostats in each room. This big box is in the kitchen and doesn't seem to do anything. Does anyone know what systems these were used with normally? Is it a whole system override? Thanks in advance for your answers.

[Markus Keller]

If she has stats in each room, they are most likely for zone valves for each room. Turn the stat on in the bedroom. Boiler kicks on, bedroom zone valve opens, boiler stays on until the bedroom stat is satisfied, doesn't care about the other rooms.
The kitchen box is probably a master on/off
You can look at the boiler, and see if there is a pipe manifold above/near the boiler, that has a bunch of brass valves with wires and a transformer on top of each to verify that the stats are for individual zone valves.

[Jim Robinson]

Never saw that one before. Possibly left over from an all electric system that was removed? I'm sure someone else has seen it before.