Vernet Thermostatic Cartridge Troubleshooting Guide

Di Vapor has teamed up with thermostatic element and cartridge manufacturers Vernet to help you service, maintain or replace your cartridge correctly, whilst providing other useful technical information. Understanding how thermostatic cartridges work can be useful for long term maintenance, ensuring that you and your family can continue to enjoy your shower or bathtub without interruption.

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If you are experiencing any problems with your output water temperature then please read the following points. Most issues can be resolved with the information in this guide.

Why is my mixed output temperature unstable?

This can be due to poor water mixing. Check that the hot and cold feeds the correct way around? A VERNET cartridge cannot have the hot and cold feeds reversed.

Why am I experiencing poor regulation and shut down difficulties?

This can be caused if the hot water supply is less than 45C. Firstly, check the cold feed and hot feed temperatures to the shower? There should be a reasonable difference between the hot and cold water supply. Cold water is generally 10-15C from the ground and hot should be set at 60-65C.

Why am I getting poor temperature regulation?

Check what water pressures are being supplied by the hot and cold? Although VERNET products can operate with unequal pressures, large differences of over 2bar will hinder the operation of the cartridge. For example, a hot water supply of 0.2 bar and a cold water supply of 3 bar could cause issues. Look into installing a Pressure Equalising Valve (PEV) for your water supplies.

Why is the water temperature different to the knob indicator after removing the cartridge?

If the cartridge has been tampered with during fitment/assessment of the shower the temperature output may not be the same as the shower indicator. If the cartridge has been removed, does the marking on the spline align with the mark on the cartridge moulding or has this been moved/ rotated by the plumber? This marking is the calibration setting from the factory at 38C.

Why is the output water temperature completely different to the knob indicator?

Perhaps the cartridge been removed and re-assembled. The locking ring fixes the cartridge inside the bore but it does need the cartridge and therefore stop ring and adjustment knob to be fitted with the calibration marks.

Tip: It is sometimes useful to let the shower cycle a few times (Hot -> Cold -> Hot -> Cold, etc) after the cartridge has been installed.