WaterBoost Slimline – Variable Speed
WaterBoost WB-INT Slimline 300 Variable Speed 2402310
- Established 1975
- Trusted by thousands of customers
The WaterBoost WB-INT Slimline 300 is a complete, pre-built variable-speed water boosting system designed to solve low water pressure and flow in 3–5 bedroom homes. Combining a 300-litre WRAS-approved upright slimline tank with the DAB Esybox Diver internal variable speed pump, it delivers up to 100 litres per minute at up to 5 bar — all in a slimline format that fits through a standard doorway.
Suitable for heat pump systems. Gives an unvented hot water cylinder the pressure and flow it needs where the mains supply falls short.
The Esybox Diver sits inside the tank, making the system exceptionally quiet and compact. It connects directly to the mains via the pre-fitted ¾” ball float valve, and WiFi connectivity via the DConnect app enables remote monitoring and voice control via Google Home and Amazon Alexa.
At 600mm diameter × 1200mm high, the Slimline tank is ideal for fitting under stairs, in a garage, or in a utility room. It arrives fully pre-assembled — no site assembly required. The tank carries a 5-year warranty and the pump a 3-year DAB warranty. Please contact us for delivery timescales.
WRAS tank & pump
Internal pump
Direct mains
Pre-assembled
PWB-2LX expansion vessel
3yr pump warranty
Check it’s the right one before you buy
Five questions and the sizer picks the tank and pump for your house.
More about this product
The WaterBoost WB-INT Slimline 300 is a complete, pre-assembled variable-speed boosting system for 3–5 bedroom homes with low mains pressure or restricted flow. A 300-litre WRAS-approved upright slimline tank pairs with the DAB Esybox Diver — an internal variable speed pump that sits submerged inside the tank itself, making this one of the most compact and quiet systems available.
Capable of up to 100 l/min and 5 bar, the Esybox Diver continuously adjusts speed to match demand across multiple simultaneous outlets. With built-in WiFi, it connects to the DConnect app for remote monitoring and works with Google Home and Amazon Alexa. The mains supply connects directly via the pre-fitted ¾” ball float valve.
At 600mm diameter × 1200mm high, the tank fits through a standard doorway — no disassembly required. Install it under stairs, in a garage, or in a utility room. 5-year tank warranty. 3-year DAB pump warranty. Please contact us for delivery timescales.
Three slimline-format upright boosting systems — all connect directly to mains, all WRAS-approved tanks. The WB-INT 300 has 50% more storage than the Powertank Slimline 200 options, higher performance, WiFi, and stronger warranties at a mid-range price.
Which should I choose?
WB-INT Slimline 300 — the best overall choice at £1,063.75 + VAT. More storage (300L vs 200L), higher flow (100 l/min vs 80), higher max pressure (5 bar vs 3 bar), WiFi and voice control, and a 5-year tank warranty — at £206.25 less than the Powertank Variable Speed.
Powertank SLIMLINE 200 Fixed — lowest cost at £744.60 + VAT. Choose if Fluid Category 4 compliance is required and flow demand is modest (40 l/min). 200L storage only.
Powertank SLIMLINE 200 Variable — Fluid Category 4 with 80 l/min variable speed, but costs £206.25 more than the WB-INT with 100L less storage, lower max pressure, and no WiFi. Choose only if Cat 4 compliance is a firm requirement.
How much does it cost and how is it delivered?
£1,063.75 + VAT (£1,276.50 inc VAT). Please contact us via WhatsApp or phone for delivery timescales on this product.
What is the Esybox Diver and how is it different from an external pump?
The Esybox Diver is a variable speed pump designed to sit submerged inside the storage tank. This means there is no separate external pump unit — the entire system is contained within the slimline tank footprint. The submerged position makes it inherently quieter and protects the pump from environmental dust and moisture. It still includes WiFi, DConnect app, Google Home, and Alexa connectivity.
Will it fit through my doorway?
Yes — at 600mm diameter, the tank is designed to fit through a standard UK doorway (760mm minimum clear opening). No disassembly is required on site. If you have a particularly narrow doorway or an awkward access route, please contact us before ordering.
How does the mains connection work?
The mains supply connects directly to the tank via the pre-fitted ¾” ball float valve. The tank fills automatically and provides a storage buffer. The Esybox Diver draws from the tank and boosts pressure throughout the property. A minimum of 0.5 bar incoming pressure is required.
Is there a larger version available?
Yes — the WB-INT Slimline 500 (£1,153.75 + VAT) provides 500 litres of storage with the same Esybox Diver pump. Choose the 500L if you have a high daily demand or a very slow-filling mains supply.
What warranties are included?
5 years on the WRAS slimline tank and 3 years DAB manufacturer warranty on the Esybox Diver pump, when purchased from Anglian Pumping Services.
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DAB Esybox Diver PDFDownload
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Data Sheet PDFDownload
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Manual PDFDownload
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 WaterBoost WB-INT Slimline 300 Variable Speed 2402310. 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 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 a water booster pump?
A water booster pump increases the pressure of an existing water supply to give stronger flow at taps, showers and appliances. It can be a small inline pump fitted to the incoming mains, or a larger pump and tank set that draws from a break tank to feed the whole house. Boosters do not create water – they raise the pressure of the water already coming in.
What is the difference between an inline booster and a tank-and-pump booster?
An inline booster connects straight onto the incoming mains and is limited to 12 litres per minute under UK water regulations – examples include the Salamander HomeBoost and WaterBoost WB-Compact. A tank-and-pump booster, such as the Grundfos Home Booster or DAB Esybox with Esytank, draws from a break tank and can deliver much higher flow rates for larger homes with multiple bathrooms.
What is a variable speed booster pump?
A variable speed booster uses an inverter to adjust pump speed in real time to match demand. It maintains constant pressure as outlets open and close, runs more quietly than a fixed-speed pump and typically saves up to 50 per cent of the energy a fixed-speed equivalent would use. The DAB Esybox, DAB Esybox Mini 3 and Grundfos Scala2 are common variable speed examples.