Controlling heating in a zone based on temperature of a node

In reference to this post about heat dumping, how would I set up a control to supply heat to a zone only if the temperature of a node (e.g. the supply outlet node of a plant loop) is above a set temperature?

I would like to limit the temperature of my plant loop to 80°C, and when that is exceeded to have a water convector in a dummy zone start to heat a highly-ventilated space which is intended to represent outdoors.

May I try it first again :).

If you created a dummy zone with a water convector I would set up an availability schedule for a water convector to 0 and than overwrite it by EMS as a function of loop temperature (for example you can use pump leaving temperature as a sensor node). EMS code should not be complex. It should look something like:

Schedule:Constant,AvailOff,On/Off,0; !- baseboard heater availability schedule

EnergyManagementSystem:Sensor, !- pump leaving water temperature node         
   PumpTemp,      
   HW Pump Out Node,   
   System Node Temperature;

EnergyManagementSystem:Actuator,
   AvailSCH_Overwrite,   
   AvailOff,       
   Schedule:Constant,     
   Schedule Value;       

EnergyManagementSystem:ProgramCallingManager,
   Overwrite Example,      
   BeginTimestepBeforePredictor, !- You might need to use different EMS calling point here
   OverwriteProg;        

EnergyManagementSystem:Program,
   OverwriteProg,       
   IF PumpTemp > 80.5,  !- I'm not sure what is the loop limit in your case, but you can add 0.5C over the limit to make a dummy heater switched on 
   Set AvailSCH_Overwrite = 1,
   ELSE,                 
   Set AvailSCH_Overwrite = 0, 
   ENDIF;

Cheers, IK