When does the pressure drop?
Note the pressure when the boiler is cold, changes during heating and how often you top up. Tell the technician how many hours or days it takes to drop again. The recommended pressure range depends on the model and system conditions.
One symptom does not identify a faulty part
Leaks in pipework or the appliance and pressure-related component issues may cause similar symptoms. The expansion vessel, safety valve and connections may be inspected. A pressure drop alone does not prove that a particular component has failed.
Information you can share
Send photos of visible water marks and the display, along with the model and last maintenance date. Do not remove the appliance cover. Instead of repeatedly adding water to compensate for a loss, request a technical inspection to find the cause.
Frequently asked questions
Does water loss mean the boiler heat exchanger is leaking?
No. This cannot be concluded without inspecting the appliance. The leak location and other possible causes must be checked.
What should I report if pressure rises and then drops?
Note cold and operating pressures, how long the change takes and any visible water marks, then share them with the technician.
General information source: Vaillant pressure information ↗. Refer to your model's user manual. Sincaplar Teknik is an independent service.