WaterBoost – CAT 5 range
WaterBoost CAT 5 WB-Coffin 500 Esybox Variable Speed 2207C120CAT5
- Established 1975
- Trusted by thousands of customers
The WaterBoost WB-Coffin 500 Esybox Cat 5 is a complete, variable-speed water boosting system that delivers the highest level of backflow protection in common use in a low-profile coffin format — fitting under stairs, inside cupboards, and in low-ceiling garages and plant rooms where an upright tank would not.
The mains supply discharges into the tank through a Type AB air gap — the float valve sits above an unobstructed air gap and the cistern carries a weir overflow sized to handle the full inlet flow. Because there is a permanent physical break between the incoming mains and the stored water, the system protects against fluids up to and including Fluid Category 5 — the most hazardous category.
The DAB Esybox variable-speed pump draws from the 500-litre tank, delivering a strong 80 l/min at 3 bar — enough for multiple bathrooms in simultaneous use, with the largest storage volume in the Cat 5 coffin range. The intelligent inverter adjusts continuously to match demand, maintaining stable pressure across every outlet with low noise and reduced energy use. Supplied complete with weir overflow, ½” connection, 1″ brass outlet and all interconnecting pipework. WiFi via the DConnect app, Google Home and Alexa compatible. 3-year DAB warranty. Delivery typically 2 to 3 working days.
Tank & pump WRAS approved · Type AB air gap — Fluid Category 5
Tank & pump WRAS approved
Type AB air gap
Low-profile coffin
Largest Cat 5 coffin
WiFi · DConnect app
Variable speed
Multiple bathrooms
Weir overflow
5yr tank · 3yr pump
More about this product
Product overview
The WaterBoost WB-Coffin 500 Esybox Cat 5 is a complete, variable-speed water boosting system that delivers the highest level of backflow protection in common use in a low-profile coffin format — fitting under stairs, inside cupboards, and in low-ceiling garages and plant rooms where an upright tank would not. It is the largest tank in the Cat 5 coffin range.
The mains supply discharges into the tank through a Type AB air gap — the float valve sits above an unobstructed air gap and the cistern carries a weir overflow sized to handle the full inlet flow. Because there is a permanent physical break between the incoming mains and the stored water, the system protects against fluids up to and including Fluid Category 5 — the most hazardous category.
The DAB Esybox variable-speed pump draws from the tank, delivering a strong 80 l/min at 3 bar and up to 6.5 bar maximum — enough for multiple bathrooms in simultaneous use. The intelligent inverter adjusts continuously to match demand, maintaining stable pressure across every outlet with low noise and reduced energy use. Supplied complete with weir overflow, ½” connection, 1″ brass outlet and all interconnecting pipework. WiFi via the DConnect app, Google Home and Alexa compatible. 3-year DAB warranty. Delivery typically 2 to 3 working days.
Tank & pump WRAS approved · Type AB air gap — Fluid Category 5
What’s included
Key features
Typical applications
Technical specifications
DAB Esybox pump
| Dimensions (W × H × D) | 352 × 564 × 263 mm |
| Max flow rate | 120 l/min |
| Flow @ 3 bar | 80 l/min |
| Max head | 65 metres |
| Max settable pressure | 6.5 bar |
| Noise | 45 dB(A) at 1m |
| Connectivity | WiFi — DConnect app, Google, Alexa |
| WRAS | Yes |
| Warranty | 3 years (DAB) |
Category 5 AB air gap tank
| Capacity | 500 litres |
| Backflow protection | Type AB air gap — Fluid Category 5 |
| Material | UV-stabilised polyethylene (blue) |
| Mains inlet | Float valve above air gap, ½” connection |
| Overflow | Weir overflow (full inlet flow) |
| Outlet | 1″ brass connection |
| WRAS | Yes — WRAS-approved Cat 5 AB air gap cistern |
| Warranty | 5 years |
Frequently asked questions
What is a Type AB air gap, and why does it matter?
It is a permanent physical break between the incoming mains and the stored water: the float valve discharges above an unobstructed air gap into a cistern with a weir overflow sized for the full inlet flow. Because nothing can be drawn back up into the mains, it gives protection against fluids up to and including Fluid Category 5 — the most hazardous category.
Should I choose the 500 or the 340?
Both use the same Esybox pump, so flow and pressure are identical — the difference is stored volume. Choose the 500 where demand is heavy or sustained, or where the incoming mains refills slowly. The 340 suits premises with a decent mains supply and shorter peaks.
Should I choose the Esybox or the Mini3?
The Esybox delivers 80 l/min at 3 bar against the Mini3’s 50 l/min, and 6.5 bar maximum against 5.5. Choose the Esybox where several outlets run at once — two or more bathrooms, or a property with high simultaneous demand. For a single bathroom the Mini3 version is usually sufficient.
What mains pressure does it need?
A minimum of 0.5 bar inlet pressure to operate the fill valve. Delivered flow and pressure are set by the pump rather than the mains, so the system suits supplies that are short on flow as well as pressure.
Does the overflow need connecting?
Yes. The weir overflow is sized for the full inlet flow and must be run to a suitable discharge point — it is the safety device that maintains the Category 5 break.
How long is delivery?
Typically 2 to 3 working days.
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Esybox Brochure 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 CAT 5 WB-Coffin 500 Esybox Variable Speed 2207C120CAT5. 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.