Why would an UFH system lose pressure?

If an underfloor heating system is losing pressure, you should check the following:

• If the system is losing pressure either during testing and/or after the system has been filled, but the flooring has not been laid, simple visual/manual checks around the manifold and along each loop of pipe should identify the problem area.
• If there are no clear visual signs, each loop/circuit may require a separate pressure test to identify the exact location.
• If the floor has been laid, identification of the fault can be traced through signs of a wet patch around the leak. Obviously to make the repair, the floor will have to be raised. In screed floors, excavate carefully in the centre of the wet patch.
• Any leaks on the manifold are generally due to the connection and any loose nuts and unions will require tightening.