Unexpected problems can happen during installation. PEX pipes can develop leaks, especially under constant high pressure (but, luckily HUG Hydronics is a low pressure system!) during installation, so it behooves the installer to check for leaks and repair or replace any leaking PEX pipes before laying concrete. Not only is this easy to do, it is required by code. It is also recommended to use the test kit to ensure a constant pressure is held during the concrete pour.