# Choose a retrofit or new-build path

Lesson 2 of [Plan a liquid cooling rollout](https://liquidcooling.fyi/academy/plan-a-liquid-cooling-rollout.md), 15 minutes.

Existing halls and new halls have different limits. Name the limits before you choose. Four retrofit paths 1. Rear-door heat exchangers. You replace the rear door of an existing rack and connect it to facility water. The change is small. Check that facility water is available at the row. 2. A liquid…

The rest of this lesson is for learners enrolled in the course. [See how Plan a liquid cooling rollout works](https://liquidcooling.fyi/academy/plan-a-liquid-cooling-rollout.md).

Also on the [web page](https://liquidcooling.fyi/academy/plan-a-liquid-cooling-rollout/choose-a-retrofit-or-new-build-path).