Grundfos STN 3.0 Bar Brass Negative Twin Impeller Shower Pump | 98284261

• Twin impeller shower pump - boosts both hot and cold water simultaneously
• 3.0 bar pressure rating - maximum head of 30 metres
• Negative head design - for systems where the cold tank sits below the shower outlet
• Brass impellers and housing - heavy-duty construction for long service life
• Regenerative pump type - handles air pockets effectively
• 52 litres per minute maximum flow rate
• WRAS approved - safe for use with drinking water systems
• 55 dB operating noise level with anti-vibration feet and silicon carbide seals
• Built-in thermal protection stops the motor if it overheats
• IPX2 rated - splash resistant enclosure
• Continuously rated - suitable for domestic and light commercial use
• 710W input power, 230V mains, ¾ inch BSP connections
• Manufacturer warranty: 5 years
• Dimensions: 271 x 225 x 283 mm

Grundfos STN 3.0 Bar Brass Twin Shower Pump for Negative Head Systems

What this pump does and who it suits:

The Grundfos STN is a twin impeller shower pump from the Amazon brass range, built to restore strong water pressure in gravity-fed (vented) hot water systems. It is specifically designed for negative head installations, meaning the water level in the cold storage tank sits at or below the level of the shower outlet - a common situation in older Irish homes with a standard cold tank in the attic feeding a hot water cylinder. It is not compatible with combination boilers or unvented pressurised systems.

Twin impeller regenerative design:

The STN boosts both the hot and cold water feeds simultaneously using two separate impellers, delivering a balanced and consistent flow to the showerhead. The regenerative impeller design gives it a natural ability to handle air pockets in the pipework, which can otherwise cause pump noise or flow interruption with centrifugal types. At 3.0 bar and a maximum flow of 52 litres per minute, it is well suited to supplying a single power shower or multiple outlets around a bathroom.

Brass construction and build quality:

The pump housing and impellers are machined brass throughout, which provides greater durability and corrosion resistance compared to plastic-bodied alternatives. Silicon carbide shaft seals are fitted as standard to extend service life and reduce wear. Anti-vibration feet are incorporated into the base to minimise transmitted noise and movement during operation, keeping the rated noise level to 55 dB.

Safety, approvals, and motor protection:

The STN carries WRAS approval (UK Water Regulations Advisory Scheme), confirming it meets full mechanical and water quality standards for use in systems supplying consumable water. The motor includes built-in thermal protection that stops it automatically in the event of overheating, protecting the pump from damage in the event of a dry run or restricted flow. The enclosure is rated IPX2, providing protection against dripping water.

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Key Features

Twin impeller design - boosts hot and cold water simultaneously for balanced shower pressure.
Negative head rated - correct for systems where the cold tank is at or below shower outlet level.
Brass housing and impellers - robust construction for long service life in hard-water conditions.
Regenerative pump type - handles air pockets without flow interruption.
WRAS approved - cleared for use with drinking water systems (approval no. 1209052).
Silicon carbide seals - long-life shaft seals reduce wear and operating noise.
Built-in thermal protection - motor stops automatically if it overheats.
Anti-vibration feet - reduces transmitted noise and movement during operation.
IPX2 enclosure rating - splash-resistant motor housing.
Continuously rated - suitable for sustained use in domestic and light commercial applications.
¾ inch BSP connections - standard UK and Irish pipework fitting size.
Flow switch included - activates the pump automatically when water flow is detected.

Specifications

• Model: Grundfos STN 3.0 (Amazon brass range)
• Part number: 98284261
• Pump type: Twin impeller, regenerative
• Head type: Negative head (universal)
• Pressure rating: 3.0 bar
• Maximum head: 30 m
• Rated head: 24.4 m
• Closed valve pressure: 3.4 bar
• Minimum static head: 1 m
• Maximum flow rate: 52 litres/min (0.6 m³/h rated)
• Input power (P1 max): 710W
• Voltage: 230V, 50Hz, single phase
• Rated current: 3.1A
• Fuse rating: 5A
• Cable length: 1.5 m (no plug fitted - hardwired installation)
• Motor type: Induction, continuously rated
• Insulation class: F
• Enclosure rating: IPX2
• Liquid temperature range: 5-60°C
• Ambient temperature range: 0-40°C
• Maximum operating pressure: 6 bar
• Inlet/outlet connections: ¾ inch BSP (G)
• Minimum pipe size: 22mm
• Housing and impeller material: Brass
• Shaft seal: Silicon carbide (GBQP)
• Flow switch: Yes
• Noise level: 55 dB
• WRAS approval: Yes (approval no. 1209052)
• Country of origin: GB
• Dimensions (LxWxH): 271 x 225 x 283 mm
• Weight: 10.3 kg (net)
• Manufacturer warranty: 5 years

What's Included in the Box

• 1 x Grundfos STN 3.0 bar twin impeller shower pump
• 4 x genuine Grundfos push-fit 22mm flexible connection hoses with filter washers
• User manual

Setup and Care

Installation requirements:

This pump is designed for hardwired mains connection and requires installation by a qualified plumber or electrician. It is suitable for gravity-fed (vented) hot water systems only and must not be used with combination boilers or unvented pressurised cylinders. Connections are ¾ inch BSP, compatible with 22mm pipework.

Positioning and siting:

The pump should be installed in a dry, ventilated location such as an airing cupboard, and must be positioned so that the cold storage tank outlet is correctly related to the pump inlet for negative head operation. Anti-vibration feet are fitted to reduce noise transmission through floors or shelving. The IPX2 rating provides basic splash protection but the pump should not be exposed to direct water spray.

Routine checks:

Periodic inspection of the flexible connection hoses and filter washers is recommended to maintain flow performance. The pump housing and connections should be checked for signs of moisture or mineral build-up, particularly in hard-water areas. Silicon carbide seals are long-life components and do not require routine replacement under normal use.

Compatibility and system check:

Before installation, confirm the existing system is gravity-fed and vented, and that the cold storage tank is correctly positioned relative to the shower outlet. The minimum static head requirement is 1 metre. If in doubt about system compatibility, consult a qualified plumber prior to ordering.

We are pleased to offer FREE delivery on orders over €499.00 to anywhere in the Republic of Ireland and Northern Ireland, and our Click & Collect service is FREE on all orders.

All items are shipped from the Athlone Warehouse in Co. Westmeath, Ireland so no import duties apply to the island of Ireland.

Delivery Costs to Republic of Ireland are €6.99 for orders Under €499.00

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Please be aware that large, bulky items (large appliances, white goods, etc.) have a delivery charge of €39.99 for bulky items or €59.99 for extra bulky items to ROI

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