How do I install 3 zones on a Triangle Tube Challenger Solo cc125 boiler?

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

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.