Accumulator Vessels
300 litre accumulator vertical GWS GCB-300LV
- Established 1975
- Trusted by thousands of customers
The GWS Challenger GCB-300LV is a 300 litre vertical accumulator from Global Water Solutions — a large pre-charged pressure vessel that stores mains water under pressure so showers and taps hold their flow when several are running, or that cuts pump starts on a booster set.
Patented CAD-2 diaphragm with a chlorine-resistant 100% butyl bladder and polypropylene liner; an air-buffer design keeps water off the shell to reduce condensation. 1¼” BSPP stainless steel connection, 10 bar max working pressure, factory pre-charged to 1.4 bar, maintenance free.
Mains accumulator
CAD-2 diaphragm
Low condensation
Potable water
Maintenance free
More about this product
What is the GWS Challenger GCB-300LV?
The GWS Challenger GCB-300LV is a 300 litre (79.2 US gal) vertical, free-standing diaphragm pressure vessel made by Global Water Solutions (GWS). It is the UK BSP version (the US NPT equivalent is the GCN-80GV) and is built around GWS’s patented CAD-2 controlled action diaphragm.
As a mains accumulator, the vessel fills from the incoming main during quiet periods and stores that water under pressure. When several outlets run at once, it tops up the flow from the main so showers and taps hold up at peak times. It does not raise static pressure: if static mains pressure is below 2 bar, add a WaterBoost WB-Compact 4.5 ACF1 accumulator booster pump to charge it to 3–4 bar.
On a booster set, the pre-charged air chamber pushes stored water out between pump starts for steadier pressure and fewer starts.
Key specifications
| Specification | Value |
|---|---|
| Brand / series | Global Water Solutions (GWS) Challenger™ |
| Model (BSP) | GCB-300LV — NPT equivalent GCN-80GV |
| Type | Vertical free-standing pre-charged diaphragm pressure vessel / accumulator |
| Nominal volume | 300 litres (79.2 US gal) |
| Connection | 1¼” BSPP, stainless steel |
| Max working pressure | 10 bar (150 psi) |
| Factory pre-charge | 1.4 bar (20 psi) |
| Operating temperature | -10 °C to 90 °C (avoid freezing) |
| Dimensions | 1513 mm high × 534 mm diameter; base 446 mm; 57 mm floor to connection |
| Gross weight | 52.6 kg |
| Diaphragm / liner | Patented CAD-2: chlorine-resistant 100% butyl diaphragm (FDA compliant), copolymer polypropylene liner |
| Shell / finish | Carbon steel, two-part polyurethane over epoxy primer; replaceable base |
| Approx. drawdown* | 93 litres at 2.0/3.5 bar (1.8 bar pre-charge) |
| Approvals | CE marked, made under ISO 9001:2015. Certification can vary by model — ask us if your project needs a specific approval. |
Choosing a size
How it’s built
GWS vertical accumulator range
| Model | Series | Volume | Connection | Height × diameter | Approx. drawdown* |
|---|---|---|---|---|---|
| PWB-35LV | PressureWave | 35 L | 1″ BSPP | 556 × 318 mm | 10.9 L |
| PWB-60LV | PressureWave | 60 L | 1″ BSPP | 619 × 389 mm | 18.6 L |
| PWB-80LV | PressureWave | 80 L | 1″ BSPP | 815 × 389 mm | 25 L |
| PWB-100LV | PressureWave | 100 L | 1″ BSPP | 805 × 430 mm | 31 L |
| PWB-130LV | PressureWave | 130 L | 1″ BSPP | 1073 × 430 mm | 40 L |
| PWB-150LV | PressureWave | 150 L | 1″ BSPP | 938 × 530 mm | 47 L |
| GCB-200LV | Challenger | 200 L | 1¼” BSPP | 1056 × 534 mm | 62 L |
| GCB-250LV | Challenger | 250 L | 1¼” BSPP | 1228 × 534 mm | 78 L |
| GCB-300LV | Challenger | 300 L | 1¼” BSPP | 1513 × 534 mm | 93 L |
| GCB-325LV | Challenger | 325 L | 1¼” BSPP | 1167 × 662 mm | 101 L |
| GCB-450LV | Challenger | 450 L | 1¼” BSPP | 1551 × 662 mm | 140 L |
*Drawdown is the water the vessel releases between pump cut-out and cut-in. Figures are calculated for a typical booster setting of 2.0 bar cut-in / 3.5 bar cut-out with the air pre-charge set at 1.8 bar. Higher pressure bands give less drawdown per litre of vessel.
Installation and pre-charge
- Check the pre-charge at the air valve with the vessel isolated and empty of water.
- On a pump system, set the pre-charge about 0.2 bar below the pump cut-in pressure (for example 1.8 bar for a 2.0 bar cut-in).
- Fit an isolating valve and drain point at the vessel so it can be checked without draining the system.
- Do not exceed 10 bar maximum working pressure, and protect from frost (minimum -10 °C, avoid freezing).
- Re-check the pre-charge at routine service visits — a wrong pre-charge is the most common cause of short-cycling pumps.
FAQs
Uses –
- 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.
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data sheet PDFDownload
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manual PDFDownload
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Dimensions PDFDownload
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Standard delivery:
Standard delivery is free on most orders. Some items may incur a delivery charge depending on weight, size or value. Any applicable charge will be displayed at checkout.
Deliveries will typically be made between 7am and 6pm, Monday to Friday (excluding public holidays).
Next day delivery:
Next working day delivery is available for a £16.50 + VAT delivery charge.
Orders must be placed before 12 noon to qualify for next working day delivery. Orders placed after 12 noon on Thursday but before noon on Friday will be delivered the following Monday. Orders placed after 12 noon on Friday will be delivered on Tuesday.
Pallet/Large/Difficult items:
Some large, heavy or difficult to transport items may incur an additional delivery charge. Please contact us for a delivery quote before ordering.
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Frequently Asked Questions
Quick answers to common questions about the 300 litre accumulator vertical GWS GCB-300LV. For technical specifications, see the product details above; for sizing or installation advice, contact our team. If you have any other questions, we're happy to help.
What is the GWS 300 litre vertical accumulator?
The GWS GCB-300LV is a 300 litre WRAS approved vertical accumulator vessel for mains-connected cold water systems. It stores mains water under pressure so when you open a tap or shower, water discharges instantly from the vessel at full mains pressure – delivering stronger, more consistent flow at every outlet. It has no pump, no moving parts and needs no routine maintenance.
What mains pressure does the GWS 300 litre accumulator need to work?
The GCB-300LV needs a minimum 2 bar static mains pressure to operate effectively. If static mains pressure is below 2 bar, pair the accumulator with a WaterBoost ACF1 accumulator charge pump – this charges the vessel to a higher working pressure. Maximum working pressure is 10 bar and the vessel is factory pre-charged to 1.4 bar.
What is a GWS 300 litre vertical accumulator used for?
It stores pressurised water to support supply during demand and reduce rapid pump cycling in appropriately designed boosting systems.
Does a 300 litre accumulator provide 300 litres of usable water?
No. The usable drawdown is lower than the vessel’s nominal capacity and depends on pre-charge and operating pressure settings.
How should a 300 litre accumulator be sized?
Sizing depends on demand, pump operation, pressure settings and the required drawdown volume; seek technical advice for the installation.
What is a mains pressure boosting system?
A mains pressure boosting system increases the pressure and flow of water from the incoming mains supply into a property. It typically combines a pump and a storage or expansion tank, drawing water from the mains and delivering it to taps, showers and appliances at a stronger, more consistent pressure. They are used where the incoming mains is too weak to serve modern outlets reliably.
When do I need a mains booster pump?
You normally need a mains booster if static mains pressure is below 1.5 to 2 bar, if showers run weakly when other taps are open, or if combi boilers struggle to deliver hot water. Anglian Pumping recommends checking static pressure at the stop tap before specifying a system, then choosing a model rated for the number of bathrooms and outlets in the property.
What size mains booster do I need for my home?
Sizing depends on the number of bathrooms, the type of fittings and the static mains pressure. As a guide, a 1 to 2 bathroom property with combi boiler or single shower often needs 1.6 to 3 bar boost. A 2 to 3 bathroom property typically needs 3 to 4.5 bar with an integral break tank. Larger homes need a tank-and-pump system such as the DAB Esybox with Esytank or a Powertank set.
What is an accumulator tank?
An accumulator tank is a pressurised vessel that connects directly to the mains supply and stores water under pressure. When a tap or shower opens, water discharges immediately from the vessel at full mains pressure rather than drawing only from the street main. This delivers stronger, more consistent flow at peak times. Accumulators have no pump and no moving parts so they are maintenance free and silent.
When should I use an accumulator instead of a pump?
An accumulator is the right solution when static mains pressure is adequate – above 2 bar – but flow is poor or drops during peak demand. It boosts available flow without adding a pump, energy use or noise. If static pressure is below 2 bar, a booster pump is needed instead, or an accumulator combined with a charge pump such as the WaterBoost ACF1.
What size accumulator do I need?
Accumulators are typically sized on a 60 per cent usable rule – a 300 litre vessel delivers around 180 litres of boosted water per cycle. As a guide, a 2 to 3 bedroom home suits a 300 litre vessel such as the GWS GCB-300LV. Larger 4 to 5 bedroom homes or properties with multiple bathrooms typically need 450 to 600 litres. Vertical models save floor space, horizontal models suit lofts and roof spaces.
What is a pressure vessel used for in a pumping system?
A pressure vessel stores water under pressure, helping maintain supply and reduce unnecessary pump starts.
What is the difference between an accumulator and an expansion vessel?
Accumulators provide pressurised water storage, while expansion vessels accommodate volume changes caused by temperature; product suitability depends on system design.
How do I choose a pressure vessel?
Consider intended use, capacity, maximum working pressure, pre-charge requirements, installation orientation and potable-water suitability.