Accumulator Vessels | Boost Water Pressure Without a Pump
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If you've ever experienced a frustrating drop in water pressure when two taps or showers run at the same time, an accumulator vessel is one of the most effective and underrated solutions available. Unlike a pump, which actively boosts pressure, an accumulator works by storing a pressurised volume of cold mains water that can be released rapidly on demand — delivering a powerful surge of water the moment a tap opens, without waiting for the mains supply to catch up. How Does an Accumulator Vessel Work? An accumulator vessel is a sealed tank divided internally by a flexible membrane or bladder. One side of the membrane is pre-charged with air or nitrogen to a set pressure; the other side fills with mains cold water. When a tap or shower is opened and demand exceeds what the incoming mains supply can deliver alone, the pressurised water stored in the vessel is released instantly to make up the shortfall. The result is a strong, consistent flow at every outlet — even when multiple are running simultaneously. Crucially, an accumulator does not increase the static pressure of your mains supply — it boosts the flow rate available on demand. If your incoming mains pressure is very low (below around 1 bar), an accumulator alone may not be sufficient and a pump or pump and accumulator combination may be required instead. If your mains pressure is adequate but flow rate drops when demand increases, an accumulator is typically the ideal fix. Who Needs an Accumulator Vessel? Accumulators are particularly well suited to properties with combination boilers that are sensitive to flow rate, homes with multiple bathrooms or showers in regular simultaneous use, properties where the incoming mains supply has adequate pressure but limited flow capacity, and any system where inconsistent hot water delivery is traced back to demand exceeding incoming supply. They are also commonly installed alongside unvented hot water cylinders and pump-assisted systems to smooth out demand peaks and red