# Chilled Water Plant Loop - Pump Error

**URL:** <https://discourse.ladybug.tools/t/chilled-water-plant-loop-pump-error/40713>\
**Category:** ladybug-tools\
**Tags:** ironbug\
**Created:** [August 24, 2026, 1:23pm UTC](https://discourse.ladybug.tools/t/chilled-water-plant-loop-pump-error/40713 "2026-08-24T13:23:32Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Mara](https://discourse.ladybug.tools/letter_avatar_proxy/v4/letter/m/71e660/32.png) [@Mara](https://discourse.ladybug.tools/u/Mara)\
**Post date:** [August 24, 2026, 1:23pm UTC](https://discourse.ladybug.tools/t/chilled-water-plant-loop-pump-error/40713/1 "2026-08-24T13:23:32Z")

</div>

Hi all,

I’m running into a reproducible bug with Ironbug’s `ChilledWaterLoop`/`CWLoop` component and wanted to check whether this is known, and whether there’s a canvas-side fix I’m missing.

**Setup:**

- Ironbug 1.21.0.0 on Rhino/Grasshopper, EnergyPlus 25.1.0
- `ChilledWaterLoop` (CWLoop) component, wired with:
  - Supply: `PlantComponent:TemperatureSource` (constant 13°C, standing in for a black-box ground source) + a pump, on the supply branch
  - Demand: three `Coil:Cooling:Water` branches in parallel

**The bug:**

```auto
**Severe** Invalid [pump] component found on equipment list.
Pumps are not allowed on equipment lists.
Problem component name = PUMP CONSTANT SPEED 1
**Fatal** InitLoadDistribution: Fatal error caused by previous severe error(s).

```

**What I’ve tried (all reproduce the identical error):**

- Switching the pump between `Pump:ConstantSpeed` and `Pump:VariableSpeed` — same fatal error either way, just with the corresponding pump type named in the equipment list.
- Changing the canvas wiring topology — merging the pump and equipment into one wire vs. feeding them into `supply` as separate/parallel connections (matching the pattern used in Ironbug’s own bundled “Chilled water loop” example file) — no change in behavior.
- Switching from `ChilledWaterLoop`/`CWLoop` to the generic `PlantLoop` component then the pump error disappear but i get:  
\*\* Severe \*\* [PlantEquipmentOperation:CoolingLoad][Plant Equipment Operation Cooling Load 1] - Missing required property ‘load\_range\_1\_lower\_limit’.  
\*\* Severe \*\* [PlantEquipmentOperation:CoolingLoad][Plant Equipment Operation Cooling Load 1] - Missing required property ‘load\_range\_1\_upper\_limit’.  
\*\* Fatal \*\* Errors occurred on processing input file. Preceding condition(s) cause termination.  
…Summary of Errors that led to program termination:  
… Reference severe error count=2  
… Last severe error=[PlantEquipmentOperation:CoolingLoad][Plant Equipment Operation Cooling Load 1] - Missing required property ‘load\_range\_1\_upper\_limit’.

**Question for the community:** is this a known issue? How could i solve it?

[Flirsch\_v11\_HVAC\_variants\_withcoolingcoil.gh](https://discourse.ladybug.tools/uploads/short-url/rV5847VrDjwBtqBYIuSrv64CsG1.gh) (1.0 MB)

 ![image](https://discourse.ladybug.tools/uploads/default/original/3X/c/b/cb4fe68e90202885c1c403df4f6befa146a9310b.jpeg)

Thanks!