Name: 300 litre accumulator vertical GWS GCB-300LV
Brand: GWS
SKU: 9039-300gws
Price: 536.4 GBP
Availability: InStock

Lowara PWB-100lv - 450 litre accumulator

300 litre accumulator vertical GWS GCB-300LV - Image 2

300 litre accumulator vertical GWS GCB-300LV - Image 3

300 litre accumulator vertical GWS GCB-300LV - Image 4

300 litre accumulator vertical GWS GCB-300LV - Image 5

In stock

Established 1975
Trusted by thousands of customers

The GWS GCB-300LV is a 300-litre WRAS-approved vertical accumulator vessel for mains-connected water systems. Accumulators store mains water under pressure — so when you open a tap or shower, you draw instantly from the vessel at full mains pressure rather than waiting for the mains to respond. The result is a noticeably stronger, more consistent flow from every outlet, even during peak demand.

The GCB-300LV operates on a 60% usable volume ratio — delivering approximately 180 litres of high-pressure water before returning to normal mains flow. Diaphragm design, patented stainless steel water connection, virgin polypropylene liner, 10 bar max working pressure, factory pre-charged to 1.4 bar. Maintenance free and WRAS approved. Suitable for 2–3 bedroom homes.

Requires a minimum 2 bar static mains pressure to operate effectively. If your static pressure is below 2 bar, add the WaterBoost ACF1 accumulator booster pump to charge the vessel to the required working pressure.

300L

Vessel size

180L

Usable output

10bar

Max pressure

WRAS

Approved

WRAS approved
Maintenance free
Diaphragm design
2–3 bedroom homes
ACF1 pump if <2 bar

Full Description

More about this product

Full Description

What is an accumulator?

An accumulator is a large pressurised vessel that connects directly to your mains supply. It stores mains water under pressure — so when you open a tap, shower, or appliance, water discharges immediately from the vessel at full mains pressure rather than drawing directly from the street main. The effect is noticeably stronger, more consistent flow throughout the home, even when multiple outlets are used simultaneously or when street pressure drops during peak demand periods.

Unlike a WaterBoost tank-and-pump system, an accumulator has no pump and no moving parts — it works entirely on mains pressure. This makes it maintenance free and silent. It is the right solution when your mains pressure is adequate (above 2 bar static) but flow is poor or inconsistent. If static mains pressure is below 2 bar, a boost pump should be added to charge the accumulator to a higher working pressure.

The GWS GCB-300LV is a 300-litre WRAS-approved vertical accumulator from GWS — built for domestic cold water installations with a patented stainless steel water connection, virgin polypropylene liner, diaphragm design, and a 10 bar maximum working pressure.

300^L

Vessel size

180^L

Usable output

10^bar

Max pressure

1.4^bar

Pre-charge

WRAS approved · Maintenance free · No pump required

How it works

1 — Vessel fills under mains pressure

The accumulator connects to the mains supply and fills automatically. The internal diaphragm compresses as water enters, storing energy as pressure.

2 — Water discharges at full pressure

When a tap or shower opens, pressurised water discharges immediately from the vessel — delivering strong, consistent flow from the first moment.

3 — Vessel refills from mains

Once demand ceases, the mains refills the vessel automatically. No pumps, no controls, no maintenance — the system is entirely self-managing.

60% usable volume rule. GWS accumulators operate on a 60% usable ratio — multiply the vessel size by 0.6 to find the volume of pressurised water available per cycle. A 300L vessel delivers 180 litres of boosted water before returning to normal mains flow. At a typical shower flow of 12 l/min, 180L supports two simultaneous showers for approximately 7.5 minutes.

Key features

WRAS approved

Fully compliant for use with potable (drinking) water in the UK. WRAS approved materials and construction throughout.

Maintenance free

No pump, no electronics, no moving parts outside the diaphragm. Once installed and charged, the GCB-300LV operates indefinitely without servicing.

Patented stainless steel connection

GWS’s patented stainless steel water connection provides a durable, corrosion-resistant interface between the vessel and pipework.

Virgin polypropylene liner

Food-grade virgin polypropylene interior liner maintains water quality and prevents contamination of potable water.

Condensation-reducing design

Two-part polyurethane, epoxy-primed paint finish minimises surface condensation — important for installations in utility rooms and garages.

10 bar max — factory pre-charged

Maximum 10 bar working pressure. Factory pre-charged to 1.4 bar for immediate commissioning. Max operating temperature 90°C.

Sizing guide

GWS recommends the following vessel sizes based on property type. All figures use the 60% usable volume rule.

Property	Recommended vessel	Usable output
1–2 bedroom home	60L, 100L or 200L	36L, 60L or 120L
2–3 bedroom home this product	200L, 250L or 300L	120L, 150L or 180L
3+ bedroom home	300L or 450L	180L or 270L

To calculate your own usage: Multiply vessel size × 0.6 to get usable litres. Divide by your total flow demand to find duration. For example: 300L × 0.6 = 180L ÷ (2 showers × 12 l/min) = 7.5 minutes of full-pressure simultaneous shower use before returning to normal mains flow.

Technical specifications

Brand / Model	GWS — GCB-300LV
Vessel capacity	300 litres
Usable output (60% rule)	180 litres per charge
Orientation	Vertical
Max working pressure	10 bar
Factory pre-charge	1.4 bar
Max temperature	90°C
Internal design	Diaphragm
Water connection	Patented stainless steel
Liner material	Virgin polypropylene
Paint finish	Two-part polyurethane, epoxy primed
WRAS approved	Yes — potable water
Maintenance	Maintenance free
Min mains pressure required	2 bar static (resting)

Frequently asked questions

How much does it cost?

£447.00 + VAT (£536.40 inc VAT). Please contact us for delivery timescales on this product.

What is the difference between an accumulator and a WaterBoost tank-and-pump system?

An accumulator connects directly to the mains and stores mains water under pressure — no pump required. It works on the pressure already available from the street main, amplifying its effect at point of use. It is the right choice when mains pressure is adequate (2 bar+) but flow is poor or inconsistent. A WaterBoost tank-and-pump system stores a much larger volume of water in a break tank and uses a pump to boost it to the required pressure. This is the right choice when mains pressure itself is below 2 bar, or where the daily volume of water needed exceeds what an accumulator can deliver per cycle. If in doubt, contact us and we’ll help you choose.

What mains pressure do I need for an accumulator to work?

A minimum 2 bar static (resting) mains pressure is required for an accumulator to charge and operate effectively. If your static pressure is below 2 bar, a boost pump — such as the WaterBoost ACF1 accumulator booster pump — should be added to charge the vessel to a higher working pressure.

How do I check my static mains pressure?

Static (resting) pressure is measured at your stop tap with all outlets closed. A simple pressure gauge fitted to an outside tap or cold water outlet will give an accurate reading. Alternatively, your water supplier can confirm the static pressure at your property’s boundary. If you’re unsure, contact us — we can advise on the best course of action.

What size accumulator do I need?

GWS recommends: 60–200L for 1–2 bedroom homes; 200–300L for 2–3 bedroom homes; 300–450L for 3+ bedrooms. The 300L GCB-300LV is ideal for 2–3 bedroom homes, delivering 180L of usable high-pressure water per cycle. For larger properties, the GWS 450L accumulator provides 270L per cycle. A GWS sizing tool is available to download from the product page.

Does the accumulator need any ongoing maintenance?

No. GWS accumulators are maintenance free — no pump, no electronics, no regular service required. The pre-charge pressure should be verified periodically (every few years) using a standard tyre pressure gauge on the Schrader valve, and topped up if necessary. This is a straightforward task requiring no specialist knowledge.

Additional Information

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.

Downloads

data sheet PDF
Download
manual PDF
Download
Dimensions PDF
Download
Sizer VND.OPENXMLFORMATS-OFFICEDOCUMENT.SPREADSHEETML.SHEET
Download

Delivery Information

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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