✔ Higher Boost Capacity than STORMBOOST
Where the STORMBOOST adds up to 2.5 bar inline, the Mainsboost Charger system delivers a system-level boost of up to 3.5 bar. Working in combination with a Mainsboost pressure vessel, the system is suited to larger properties, multi-bathroom dwellings, multiple-occupancy buildings, and light commercial applications where a simple inline booster is insufficient. It is the solution when mains pressure is below 2.5 bar and higher sustained flow is required.
✔ Wall-Mounted — Remote Location from Vessel
Unlike the MJ3 Charger variants (which mount directly on to the vessel), the MBC 12-22 WM mounts independently on the wall, allowing the pump to be positioned remotely from the Mainsboost vessel without any penalty to performance. This is valuable in installations where the vessel is in a confined space (e.g. a cupboard or riser) but a more accessible wall location is preferable for pump maintenance and service access.
✔ Noise-Reducing Steel Enclosure
The pump is supplied within a robust steel housing lined with acoustic foam, achieving a typical noise level of 60 dB(A) — significantly quieter than many comparable mains booster pumps of this output class. This makes the MBC 12-22 WM suitable for wall-mounting in occupied domestic environments such as utility rooms and hallways without disruptive noise.
✔ Patent-Protected Mainsboost System
The Mainsboost system design is protected under system patent no. 2349908. The combination of charger pump and accumulator vessel provides a fundamentally different — and more capable — approach than simple inline mains boosting: the vessel absorbs demand surges and the pump charges to a set pressure, delivering consistent pressure and flow even during peak simultaneous demand at multiple outlets.
✔ Compatible with All Mainsboost Vessels
The MBC 12-22 WM is compatible with the full range of Stuart Turner Mainsboost steel and composite pressure vessels — the appropriate vessel size is selected based on the property's peak hot water demand and the number of occupants/bathrooms. Stuart Turner provides a site survey form and sizing guidance to assist specification.
✔ Dry Run Protection
Integrated dry run protection shuts the pump down if it detects operation without water flow — for example if the mains supply is interrupted or isolated. This protects the mechanical seal and impeller from damage and restores normal operation once mains flow resumes. The induction motor also incorporates an auto-reset thermal trip for overtemperature protection.
✔ Solid Brass Pump Head & Impeller
The pump head and impeller are manufactured from solid brass, with an EPDM / PTFE / Aluminium Oxide mechanical seal — the same robust construction used throughout the Stuart Turner mains boosting range. Brass provides excellent resistance to corrosion in cold mains water systems and ensures a long service life with minimal maintenance.
✔ Pre-Wired, IPX4 — Ready to Connect
The pump is pre-wired with a 1.5-metre power cable ready for connection to a fused spur. The IPX4 enclosure rating (splash-resistant) means it can be wall-mounted in typical plant room, utility room, and under-sink environments. Two anti-vibration flexible hoses are included for connection to the 15mm pipework (G¾ female, 235mm and 200mm lengths).
✔ Made in Britain — 5-Year Warranty
Designed and manufactured by Stuart Turner in the United Kingdom — the same engineering heritage as the STORMBOOST and Showermate ranges. The MBC 12-22 WM carries a 5-year warranty, with UK-based technical support (TechAssist) and a national network of approved service engineers available.
What is the difference between the Mainsboost Charger and the STORMBOOST?
The STORMBOOST (47708) is a standalone inline mains booster pump — it installs directly in the rising main and works autonomously with no additional components. It adds up to 2.5 bar and is designed for single-bathroom properties with a combi-boiler where a simple pressure lift is needed. The Mainsboost Charger MBC 12-22 WM is a system pump — it must be used with a Mainsboost pressure vessel (accumulator). The combination delivers up to 3.5 bar of system boost, handles simultaneous demand from multiple outlets, and is suited to larger or multi-bathroom properties, HMOs, and light commercial premises. The Mainsboost system provides higher sustained flow and better pressure stability under variable demand.
Which Mainsboost vessel do I need to pair with this pump?
The appropriate vessel size depends on peak simultaneous demand — the number of bathrooms, occupants, and the type of outlets (showers, unvented cylinders, combi-boiler, etc.) that may be used concurrently. Stuart Turner provides a site survey form (downloadable from their website) to assist in correct specification. The MBC 12-22 WM is compatible with all Mainsboost steel and composite pressure vessels. For large installations or if you are unsure, contact us or use the Stuart Turner TechAssist service for sizing guidance.
Why choose the wall-mounted MBC 12-22 WM rather than the vessel-mounted MJ3 Charger?
The MBC 12 (wall-mounted) allows the pump to be positioned remotely from the Mainsboost vessel without any restriction to performance — useful where the vessel is in a confined space (a cupboard, riser shaft, or plant room) and a more accessible wall location is required for maintenance. The MJ3 (vessel-mounted) mounts directly onto the vessel and is a more compact solution where the pump and vessel can be co-located. Both options deliver identical system performance.
What is the difference between the 22 WM (44725) and the 28 WM (44726)?
The only difference is the bypass connection kit supplied with each unit. The 44725 (MBC 12-22 WM) comes with a 22 mm bypass kit for installations where the cold water rising main is 22mm pipework. The 44726 (MBC 12-28 WM) comes with a 28 mm bypass kit for 28mm mains pipework. The pump unit itself is identical. Choose the variant that matches your installation's rising main pipe size.
What electrical connection does it require?
The MBC 12-22 WM is pre-wired with a 1.5 m power cable and requires connection to a 3A fused spur (230V a.c. / 1ph / 50Hz). At 398W / 1.8A full load, it draws well within a 3A circuit. The electrical installation must comply with current national electrical regulations and be carried out by a qualified electrician. A 30 mA RCD is recommended for additional safety in line with best practice for pump installations.
