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Safety Alert 033

Developed with Morco Products

Morco open flued water heaters
Date issued: 
15 November 2023

This Safety Alert provides guidance to Gas Safe registered businesses/engineers about a product safety concern related to some Morco open flued water heaters.


Gas Safe Register has been made aware of a concern regarding the test nipple screws on Morco water heaters that may not have been correctly operated. This could result in the unintentional release of unburnt gas causing fires, and potential injuries.



Morco is currently investigating a potential fire risk on its Primo 6 (MP6), Primo 11 (MP11), EUP6 and EUP11 open flued water heaters, due to possible gas leaks igniting and causing the plastic bezel and control knobs to ignite and melt.

Early indications point to the test nipple screws (gas inlet and burner pressure) not being tightened and checked correctly for any gas leak as per the installation manuals after the appliances have been commissioned, serviced or maintained. The below pictures show the exact location of the test points on each of the affected appliances.

Primo 11 (MP11)

Primo 6 (MP6)

Primo 6 (MP6)

EUP6 / EUP11

Corrective actions

Leak detection fluid (LDF) should be used after every time the test points are loosened to ensure a guaranteed seal after screwing tight each type of pressure test nipple screw, ensure that all seals are present for the Primo models. When you are checking the burner pressure test nipple screws for all models, the water heater must be in demand. To complete these checks either a 4mm slotted screwdriver or a Phillips No2 screwdriver will be required.

If you have any questions or safety concerns, please contact Morco Products on 01482 386586 or via email at


Note: Gas Safe Register Technical Bulletins and the Legislative, Normative & Informative Document List can be viewed online. Engineers can login to and visit the Technical Information area.