Water-cooled VRF+Boiler do not handle heating load
Has anyone been able to handle heating load with a combination of Water-cooled VRF + Boiler?
My project has water-cooled VRF which is connected to cooling tower and boiler. I created the HVAC system with HVACTemplates (Zone:VRF, System:VRF, Plant:Tower, Plant:Boiler and Plant:MixedWaterLoop) in EnergyPlus 9-4-0.
The calculation completes, and cooling in summer works fine, but there is no heating in winter even though there are a very large heating load. No electricity and natural gas are used. Almost all the heating periods are counted as unmet hours.
When I change Condenser Type in HVACTemplate:system:VRF from WaterCooled to AirCooled, VRF handles heating load well. So, I think there is something wrong with MixedWaterLoop, but I don't know what it is. Operation Scheme Type in HVACTemplete:Plant:MixedWaterLoop is Default. I tried various Temperature Design Setpoint settings, but they didn't work. MixedWater is properly selected as Templete Plant Loop Type in HVACTemplete:Plant:Boiler.
I also tried to created the WSHP system with HVACTemplete:Zone:WaterToAirHeatPump instead of VRF, but I faced exactly the same problem with heating in winter.
I'd really appreciate it if someone could tell me why it doesn't go well.
P.S. Here is a screenshot of my svg file.
@Keigo there has been a similar question posted here, which mentions that "the VRF model does not account for the impact of other zone equipment on the operation of the VRF system". Do you have other HVAC equipment meeting the zone's heating loads?
Also, have you reviewed the SVG diagram of the VRF condenser loop with the cooling tower and boiler to confirm that components are located correctly?
@Aaron Boranian Thank you for your comment. Yes, there is a previous similar post, and my original model has DOAS, but even if I remove the DOAS, VRF still doesn't handle the heating load. End use energy is 0.
I had not reviewed the SVG diagram. I looked at it and both air-side loop and water-side loop seem to be no problem. One concern is that there is a note saying "Unused Non-Parent Objects: MXLOOP MIXED TEMP MANAGER", but I don't know how to revise my model. FYI, I uploaded a screenshot of the SVG diagram (The number of zones is reduced to simplify the model).
@Keigo check out the apartment-highrise prototype model as a reference, it uses WSHPs with a boiler/cooling tower source water loop.
@ericmartinpe Currently, I'm using HVACTemplate because my project is still in the very early stage and needs a rough but quick simulation, but the link will be very useful in the future. Thanks!