I bought a Triangle Tube Challenger Solo cc125 boiler and the installation instructions shows multiple zones. However, I can only see one set of thermostat terminals in the on-board wiring. Do I have to add zone controls to use three circulator pumps and three thermostats?


For a multiple zone installation, each zone will require a thermostat in that zone to control a zone valve with an end switch to turn the boiler on/off or a thermostat to control the boiler and each pump. each pump will have to be coupled with a flow control valve. d george

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    In some system, the pumps themselves act as zone control, without explicit valves controlled by the thermostats. – keshlam Dec 28 '16 at 4:54

You will need some sort of pump switching relay to control multiple zones. This Taco switching relay should be what you need. They make all types of zone controls. Check pages 37-39 in the manual found Here and it will show you a wiring diagram of how the manufacturer recommends its installed.

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