Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
You want to place both the heat pump and the boiler on the supply side of the plant loop, on parallel branches is fine.
You want your PlantLoop Load Distribution Scheme to be SequentialLoad, and you want a PlantEquipmentOperation:HeatingLoad attached to the PlantLoop that references a PlantEquipmentList that has the heat pump first, then the boiler. This will ensure the heat pump gets loaded first, then the boiler.
You can either rely on OpenStudio inner workings, and connect the Heat Pump first to the PlantLoop, then the Boiler:HotWater and this should produce what you want, and you should check the resulting E+ IDF file to make sure.
Or you can use the Ruby bindings (API) to create your own custom PlantEquipmentOperationHeatingLoad, it's maybe more complicated but you're sure to produce the right one...
