Hybrid GSHP - Backup boiler doesn't come on

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Good Afternoon!

I'm working on a building with a water-source heat pump system. The designers want to use an adjacent river as a heat source/sink, but they want to include a backup boiler as the river regularly freezes in the winter. The boiler would preheat water from the river intake before it gets distributed to the heat pump evaporators. I started this project in eQuest 3.65, since it can model hybrid systems. However, even though I can attach the boiler to the water-loop heat pump loop along with the river heat source, when I run a simulation the boiler never comes on. I've tried adding an equipment control and load management scheme to the loop (admittedly, I'm a novice when it comes to that area of eQuest), but that just makes the simulation crash. I've attached the project files if anyone want to take a look. Is there a way to control the backup boiler so that it comes on above a certain heating load, or when the river water dips below a certain temperature?


Drew Morrison
Energy Engineer

dmorrison at slipstreaminc.org
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Drew Morrison | Energy Engineer Slipstream 608.210.7151 slipstreaminc.org
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