> For the complete documentation index, see [llms.txt](https://docs.betterbuilding.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.betterbuilding.io/user-guide/workflows/energy-efficiency/advanced-hvac/modelling-four-pipe-heat-pumps.md).
# Modelling four-pipe heat pumps
A four-pipe heat pump is a device capable of providing cooling and/or heating, separately or simultaneously. It is also referred to as a multi-function chiller.
{% hint style="warning" %}
Advanced HVAC enables you to model four-pipe heat pump systems using the [EnergyPlus HeatPump:PlantLoop:EIR:Cooling (and Heating) objects](https://bigladdersoftware.com/epx/docs/22-2/input-output-reference/group-plant-equipment.html#plhp_eir). Please note that this does not account for heat recovery - this object assumes that only one side (either heating or cooling) will be active at any given simulation timestep.
{% endhint %}
To model a central air handling unit system with a four-pipe heat pump system providing the cooling device on a chilled water loop and the heating device on a hot water loop, follow these steps.
This will create a four-pipe heat pump system central plant component, along with two related (children) objects: 1) Four-pipe heat pump (Heating) on the hot water loop and 2) Four-pipe heat pump (Cooling) on the chilled water loop.
{% hint style="success" %}
On the HVAC Schematic, select 'Select Template'. Next, choose 'Four-pipe Heat Pump System' from the list and complete the other form options as desired.
{% endhint %}
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.
Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:
```
GET https://docs.betterbuilding.io/user-guide/workflows/energy-efficiency/advanced-hvac/modelling-four-pipe-heat-pumps.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.
