Name: WaterBoost WB-Compact 4.5 low mains pressure booster (ACM Series)
Brand: WaterBoost
SKU: acm
Price: 552 GBP
Availability: InStock

WaterBoost WB-Compact 4.5 low mains pressure booster (ACM Series)

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In stock

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.

4.5bar

Max boost

12l/min

Max flow

No
tank

Inline mains

3yr

Warranty

WiFi · DConnect · Google · Alexa
WRAS compliant
Direct mains — no tank
Variable speed
ACM Series
Silent operation

Full Description

More about this product

Full Description

Product overview

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.

4.5^bar

Max boost pressure

12^l/min

Real-world @ 3 bar

1^“

BSP connection

3^yr

Warranty

WRAS approved — direct mains connection

Key features

Highest boost in the range

Boosts up to 4.5 bar — the most powerful direct mains booster pump in the WB-Compact range. Real-world output of 12 l/min at 3.0 bar.

Direct mains connection

Connects inline to your incoming mains — no break tank or storage required. WRAS approved for direct mains use.

Silent variable speed

Digital variable speed design maintains stable pressure with minimal flow reduction, even when multiple outlets are open.

WiFi and voice control

DConnect app for remote monitoring and control. Google Home and Amazon Alexa compatible — “Hey Google, power shower.”

WRAS approved

Compliant with water authority regulations. Flow rate capped at 12 l/min in line with water authority requirements.

Automatic pressure sensing

Activates automatically when mains pressure drops below the pre-set value and switches off when demand stops.

Full-bore bypass option

A full-bore bypass can be fitted to maintain uninterrupted water supply during pump maintenance.

3-year warranty

3-year warranty when purchased from Anglian Pumping Services.

Wall bracket available

Optional ACM wall bracket (£42 + VAT) for a clean, professional wall-mounted installation.

Typical applications

Properties with very low mains pressure

Where the 3.0 bar model is insufficient — the 4.5 delivers the highest boost available inline.

Electric showers

Boosts mains pressure to well above the minimum threshold required by electric showers.

Mixer showers

Consistent balanced pressure to hot and cold feeds for thermostatic mixer showers.

Combination boilers

Ensures combi boilers receive adequate mains pressure for efficient hot water and heating.

Unvented hot water cylinders

Provides the pressure needed for unvented cylinders to operate correctly and safely.

Whole-house mains boosting

Installed at the incoming mains to boost pressure to the entire property from a single point.

Pressure vs flow — which do you need?

Low pressure

The WB-Compact 4.5 is the right choice

Your taps and showers feel weak even when only one is running. Pressure is measured in bar — the legal minimum at your stop tap is 0.7 bar. The WB-Compact 4.5 boosts this up to 4.5 bar — the highest of any inline mains booster we stock.

Low flow

An accumulator may be more effective

Pressure is fine with one tap but drops when others open. This is often a restricted supply pipe. A booster pump cannot create flow that isn’t there — an accumulator stores water to compensate. Contact us if you’re unsure.

Technical specifications

Model	WaterBoost WB-Compact 4.5 (ACM Series)
Max boost pressure	4.5 bar
Max flow rate	12 litres per minute
Real-world output	12 l/min at 3.0 bar
Connection size	1″ BSP
Installation type	Inline — direct mains connection
Connectivity	Built-in WiFi — DConnect app, Google Home, Amazon Alexa
Bypass option	Full-bore bypass available
WRAS approved	Yes — suitable for direct mains connection
Warranty	3 years
Price	£460.00 + VAT (£552.00 inc VAT)

How it compares

All three direct mains booster pumps stocked by Anglian Pumping Services — compared side by side. Real-world output figures shown at typical working conditions.

Feature	WB-Compact 4.5 this product	WB-Compact 3.0	Stuart Turner Stormboost
Max boost pressure	4.5 bar	3.0 bar	2.5 bar
Real-world output	12 l/min @ 3.0 bar	11 l/min @ 3.0 bar	10 l/min @ 1.9 bar
Max flow rate	12 l/min	12 l/min	12 l/min
Motor type	Digital variable speed	Digital variable speed	Fixed speed induction
WiFi / app	Yes — DConnect	Yes — DConnect	No
Voice control	Google & Alexa	Google & Alexa	No
Connection	1″ BSP	¾″ BSP	¾″ BSP
Bypass	Optional full-bore	Optional full-bore	Patented integral
WRAS approved	Yes	Yes	Yes
Warranty	3 years	3 years	5 years
Price (ex VAT)	£460.00	£355.00	£245.00

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.

Frequently asked questions

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.

Additional Information

Low Water Pressure

Water pressure can vary throughout the day, typically dropping during the morning and evening when demand is highest as more people use water at home.

Pressure is measured in bars, with 1 bar of pressure capable of pushing water to a height of 10 metres within your home. The legal minimum water pressure required at your boundary stop tap is 7 metres head (0.7 bar). However, the WaterBoost WB-Compact 4.5 mains booster pump can significantly increase this, boosting pressure up to 4.5 bar!

If you’re not on a shared supply, your neighbours should experience similar water pressure to yours, provided your homes are of similar height and located at the same distance from the water main. However, water flow can vary individually between properties.

It’s important to distinguish between low water pressure and low water flow. You may have high pressure but still experience a low flow rate, often due to limitations in your private supply pipe. In such cases, an accumulator may be a more effective solution than a booster pump.

Downloads

Install Guide PDF
Download
Data Sheet PDF
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.