Why your new combi boiler has low water pressure is a common concern for homeowners after installation. Many people expect instant strong flow from a new system, but pressure issues can still occur if other factors limit performance. Understanding the cause helps you fix the issue quickly and avoid unnecessary worry.
Combi boilers deliver hot water directly from the mains. This means water pressure depends heavily on the incoming supply rather than the boiler itself. If your property already has low mains pressure, a new boiler will not magically increase it. Older South London properties often experience this issue due to ageing pipework or shared supply lines.
Internal pipework can also restrict flow. Narrow pipes, old fittings, or partially closed valves reduce pressure at taps and showers. Limescale buildup can further restrict flow over time, especially in hard water areas.
In some cases, the issue comes from the filling loop or pressure settings. Boiler pressure should remain within the recommended range for proper operation. Incorrect setup during installation can lead to poor performance.
Fixing low pressure starts with a professional assessment. Engineers check mains pressure, inspect pipework, and confirm correct boiler setup. In some homes, upgrading pipework or fitting suitable shower equipment resolves the issue.
OJ Gas & Heating provides expert combi boiler assessments across South London. Their engineers identify the true cause of low pressure and recommend practical solutions that restore comfort and performance.
