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How to Install an AccuBoost Accumulator Vessel

For homes that suffer with low mains water pressure or flow, installing an accumulator vessel can be an easy and effective way of improving the water performance of taps, showers, baths, and other outlets across the house.

Our AccuBoost range includes accumulators suitable for unvented cylinders or combi boilers and has been designed to be easy to specify and install.

An accumulator vessel installation may seem like a daunting task, but it doesn’t need to be! We’ve developed a range of resources to guide you through every step in the process from specification to installation. In this guide we provide a step-by-step explanation of how to install an accumulator vessel.

Select the location

AccuBoost vessels can be installed in various locations, including kitchen cupboards or in the garage, anywhere it can be connected to the mains water supply.

Pumped models should be fitted as the first point of contact after the stop tap. However, if this isn’t possible due to space constraints the pump can be fitted remotely from the vessel. The pump must be the first thing in the system and be located within 5 metres of measured 22mm pipework (this can include a maximum of 2m of 15mm pipe) of the stopcock.

Unpumped models can be ‘teed’ in anywhere in the system, but only outlets that are after the non-return valve will see the benefit.

Unbox AccuBoost

Unbox the product and read through the installation guide. The installation guide should always be your first port of call, it provides you with a pre-installation checklist, product descriptions, technical specifications, and step-by-step instructions.

Turn off the mains

Turn off the home’s mains water supply and then drain down the system.

Make provision for the mains cold feed

Once drained, make a provision for the cold mains to be taken to the AccuBoost vessel.

Install valves

Next, you’ll need to install the necessary valves. The accumulator vessel installation diagrams to the right show which valves are necessary and how they should be installed.

You will need to install a double-check valve, then a pressure reducing valve before the AccuBoost unit. A maintenance bypass should also be fitted.

For unpumped vessels we recommend fitting an inline strainer after the stop tap, to allow the system to retain the built-up pressure.

Create a connection to the mains

If you’re installing a pumped AccuBoost, create a connection from the mains to the pump inlet, and a connection from the AccuBoost pump outlet to the system.

For unpumped AccuBoost models, create a direct connection between the mains supply and the AccuBoost vessel.

Set the pressure

For pumped vessels, the pre-charge air pressure of the vessel is pre-set.

However, unpumped accumulator vessel models pressure need to be set at 1.5 bar less than the natural mains pressure.

See our FAQ’s page to learn how to check the pre-charge pressure of an accumulator tank vessel.

Turn the stop tap on

Turn the stop tap back on and open the isolation valves to allow water in to the AccuBoost.

For pumped models, you will also need to plug in the pump and switch it on.


The mains water pressure and flow around the home should now be noticeably improved.

How to install the AccuBoost Accumulator Vessel

How to Install the AccuBoost Accumulator Vessel

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