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HW Preheat coil in HVACTemplate:System:VAV causing crash

asked 2018-07-06 11:10:27 -0600

Abarker's avatar

updated 2018-07-07 10:37:45 -0600

Im trying to set up about 8 VAV systems using the HVAC template objects. EnergyPlus is either crashing or terminating prior to the simulation starting when I specify a Hot Water preheat coil in these objects with a 15C setpoint.

This is the only difference between a running and non-running model. I do have the required boiler and hot water loop template objects with plenty of other coils requiring them. The boiler capacity is autosized.

It does not crash when I specify an electric coil (it does still crash when I modify the setpoint e.g. to the default 7.2 C), leading me to believe this might have to do with the boiler capacity and or hot water loop configuration. What would cause this though? Model was running fine before this change.

Any thoughts are appreciated.


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I tried to reproduce this starting with the HVACTemplate-5ZoneVAVWaterCooled example file. Added a HW preheat coil, first with blank (default) temperature setpoint, then with 7.2C, then with 15C, and all ran fine. So I'll need your idf files (preferably one that runs OK and one that fails) in order to diagnose. Please post a link here or send to

MJWitte's avatar MJWitte  ( 2018-07-10 08:09:07 -0600 )edit

Commenting to say that I was able to rectify this situation by modifying the preheat coil temperature set-point of the systems. I don't seem to have a file which doesn't run any longer, and... cant seem to recreate one either. Chalk it up to poor file management on my part. However, I am guessing this a local issue or some odd scenario I stumbled in and out of without realizing. Thanks for the help.

Abarker's avatar Abarker  ( 2018-07-23 14:22:15 -0600 )edit

I think that this problem is associated with the problem in this post. When I replaced all my VAV HW Rht Coils with electric reheat, I was able to fix that problem. It may have to do with the topology/setup of my system on the air or plant side. I am a beginner so I am not sure.

IanVG's avatar IanVG  ( 2022-10-05 15:20:12 -0600 )edit

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answered 2022-10-05 15:42:24 -0600

IanVG's avatar

updated 2022-10-05 15:43:23 -0600

Okay I got the solution: if a VAV HW Rht Coil is added to the demand side of a system, you have to assign the VAV HW Rht Coil to a Plant Loop (a different process for some reason than adding a regular hot water heating coil to a plant loop).

On the plant there is not a node that auto links the coil to the air-side system, but I do not know if there is a good reason for this.

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Asked: 2018-07-06 11:10:27 -0600

Seen: 140 times

Last updated: Oct 05 '22