WaterBoost Mains Booster
WaterBoost WB-Compact 4.5 low mains pressure booster (ACM Series)
- Established 1975
- Trusted by thousands of customers
The WaterBoost WB-Compact 4.5 (ACM Series) is a compact variable speed inline mains pressure booster — designed to boost your incoming mains supply to up to 4.5 bar at up to 12 l/min. It installs directly on your mains supply pipe and starts automatically whenever mains pressure falls below its pre-set value — no break tank or storage vessel required. Suitable for combination boilers, unvented hot water cylinders, electric showers, and mixer showers.
Variable speed inverter maintains stable pressure as demand changes, even with multiple outlets in use simultaneously. WiFi via the DConnect app enables remote monitoring and control, with Google Home and Alexa voice commands — say “Hey Google, power shower” to boost pressure or “Hey Google, sleep mode” to quieten it overnight. Silent operation. Full-bore bypass can be fitted for uninterrupted supply during maintenance.
WRAS compliant — flow rate remains within the water authority limit of 12 l/min. If 3.0 bar is sufficient for your application, see the WB-Compact 3.0 (£355 + VAT). 3-year warranty.
WRAS compliant
Direct mains — no tank
Variable speed
ACM Series
Silent operation
More about this product
The WaterBoost WB-Compact 4.5 is a direct mains inline booster pump designed for properties requiring the highest levels of mains pressure boosting. It connects directly to your incoming supply and automatically activates when pressure falls below a pre-set value, boosting it to up to 4.5 bar — the highest in the WB-Compact range.
Its digital variable speed design delivers a real-world output of 12 l/min at 3.0 bar, maintaining stable pressure with minimal flow reduction even when multiple outlets are in use simultaneously. With silent operation and small-bore pipe compatibility, it is the most capable direct mains booster pump we stock.
Connects to the DConnect app via WiFi for remote monitoring and voice control via Google Home and Amazon Alexa. WRAS approved and compliant with water authority regulations. Backed by a 3-year warranty.
All three direct mains booster pumps stocked by Anglian Pumping Services — compared side by side. Real-world output figures shown at typical working conditions.
Which should I choose?
WB-Compact 4.5 — the highest performing inline mains booster we stock. Best for properties with very low pressure, larger homes, or where maximum performance is the priority. Connects via 1″ BSP.
WB-Compact 3.0 — a strong choice for most domestic properties. Slightly lower real-world output (11 vs 12 l/min at 3 bar) and max pressure (3.0 bar) but costs £105 less and uses ¾” BSP.
Stormboost — the budget option at £245 + VAT. Lower real-world output (10 l/min at 1.9 bar) and no smart features, but comes with a 5-year warranty and integral bypass included as standard.
How much does it cost and how is it delivered?
£460.00 + VAT (£552.00 inc VAT). Standard delivery is free for this product, including next working day when ordered before 12 noon on a working day. In stock and ready to dispatch.
Can this pump connect directly to the mains?
Yes — the WB-Compact 4.5 is WRAS approved for direct inline mains connection. No break tank or storage cistern is required. It fits into the incoming supply pipework and boosts pressure throughout your property from a single point.
Do I have low pressure or low flow — what’s the difference?
Low pressure means your taps feel weak even when only one is running — the WB-Compact 4.5 is designed for this. Low flow means pressure is fine with one outlet but drops when more open — typically caused by a restricted supply pipe. A booster pump alone cannot solve low flow. An accumulator tank is usually the right solution. Contact us if you’re unsure.
What is the difference between this and the WB-Compact 3.0?
The WB-Compact 4.5 boosts up to 4.5 bar and delivers a real-world output of 12 l/min at 3.0 bar — one litre per minute more than the 3.0 at the same pressure. It also connects via 1″ BSP rather than ¾”, which suits properties with larger bore pipework. It costs £105 more than the 3.0. For most standard domestic properties the 3.0 is sufficient, but if you need maximum output or have a larger home, the 4.5 is the better choice.
Will it boost pressure to my whole house?
Yes — installed at the incoming mains it boosts pressure to the entire property. Real-world output of 12 l/min at 3.0 bar, with the variable speed design maintaining stable pressure even when multiple outlets are open simultaneously.
Is it suitable for my combi boiler / electric shower / unvented cylinder?
Yes — the WB-Compact 4.5 is suitable for combination boilers, electric showers, mixer showers, and unvented hot water cylinders, all of which require a minimum incoming pressure to operate correctly.
How does the WiFi and voice control work?
The pump connects to the DConnect app via built-in WiFi for remote monitoring and control. It also integrates with Google Home and Amazon Alexa — say “Hey Google, power shower” to boost pressure, or “Hey Google, sleep mode” to switch off at night.
What is a full-bore bypass and do I need one?
A full-bore bypass is a parallel pipe that allows water to flow directly from the mains if the pump is being serviced or removed, maintaining uninterrupted supply. It is optional — most domestic installations do not need one — but recommended where any interruption to supply would be problematic.
What warranty is included?
3 years when purchased from Anglian Pumping Services.
Is a wall bracket available?
Yes — the optional WaterBoost ACM wall bracket (£42.00 + VAT) allows clean wall-mounted installation. A connection kit and braided hoses are also available — see the “You may also need” section on this page.
-
Install Guide PDFDownload
-
Data Sheet 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.
You may also need
The WaterBoost ACM wall bracket is a fitting kit designed to mount the ACM pump directly to a wall.
DAB AC connection hoses 300mm long to 22mm connection
WaterBoost ACM connection kit Pump to pipework connection kit for easy instaltation. includes – 2 x 600mm 1″ braided hose 2 x 22mm x 1″…
Related products
The WaterBoost WB-Coffin 200 Mini3 is a compact, variable-speed water boosting system engineered to overcome low water pressure or inadequate flow in domestic and light…
The WaterBoost WB-EXT Slimline 300 Mini3 is a variable-speed water boosting system combining a 300-litre WRAS-approved slimline tank (600mm dia × 1200mm high) with the…
The WaterBoost WB-Advant 1000 Esybox provides large-scale boosting for high-demand domestic and light commercial properties. A 1000-litre WRAS-approved UK-manufactured Advant tank (760mm W × 1225mm…
Frequently Asked Questions
Quick answers to common questions about the WaterBoost WB-Compact 4.5 low mains pressure booster (ACM Series). 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.