GWS GCB-300LV accumulator

How to specify the best and correct size Accumulator

Accumulator vessels offer a great solution to low water pressure in a home, however, with so many different vessels available, choosing the right accumulator for the job can seem like a complicated process.

To help simplify the specification process, our Managing Director, Glen Denny, explains how to choose the correcrt accumulator for your systems.

1. Does the home have a combi boiler or an unvented system?

Accumulator vessels are suitable for both combi boilers and unvented systems indeed any pressurised system. If your mains pressure is below 2 bar you will be required to add a pump to increase the pressure.

The best selling DAB ACF1 is used to increase mains pressure up to 4.5bar.

2. What size accumulator vessel do you need?

To specify what size accumulator vessel a home needs, calculate the flow rate (l/min) of the outlets in the home that you want to run at any one time. You can then identify the correct accumulator vessel sizing to provide this flow rate. We normally use a figure of 12 l/min per shower. An Example of GWS sizing is below –

1 to 2 bedroom house – 60 litre,100 litre or 200 litre

2 to 3 bedroom thouse – 200 litre, 250 litre or 300 litre

3 bedrooms and above – 300 litre or 450 litre

Remember GWS accumulators operate on a 60% volume to use ratio meaning a 300 litre vessel gives 180 litres of powerful water before returning to mains flow.

To find your vessel usage times vessel size by 0.6.

An average shower/bath runs at 10-12 litres/min. So 300 litre GWS x 0.6 = 180 litres. This will operate 2 showers at 12 litres/min for 180 / (12 litres/min x 2 ) = 7.5 minutes.

3. Do I require a pump?

If the mains static pressure is below 2bar then a booster pump is required. The most popular option is the DAB ACF1 pump. This innovative pump increases water pressure to a maximum of 4.5 bar, with pressure settings easily adjustable via its intuitive LCD display.

4. How much space is required?

In general, a 60L model will fit into a standard 500mm kitchen base unit; a 100L model into a 500mm larder style kitchen unit; and the 200L/300L model into a 600mm larder style kitchen unit with the back removed (although the vessels don’t have to be situated in the kitchen and can indeed be installed horizontal in lofts).

If space is limited, you may need to specify a smaller vessel and to link multiple vessels together to gain additional capacity and make the solution flexible to the available space.

5. Do you have further questions?

If you’re still unsure which accumulator vessel is right for your needs, Anglian Pumpoing Services has the technical expertise to help.