The McDonald Water Storage 250 Litre Heat Pump STEELflow Pre-Plumbed Cylinder is a pre-plumbed, unvented duplex stainless steel cylinder designed for air source or ground source heat pumps, providing high-capacity hot water storage with integrated components for enhanced system efficiency.

Product Description

The STEELflow Heat Pump Cylinder is manufactured from duplex stainless steel for superior corrosion resistance, specifically engineered for low-temperature heat pump applications. With a 250L capacity, it optimises flow rates and reduces cycling, improving overall system performance. Pre-plumbed with essential components like expansion vessel, pump, and valves, it ensures quick installation and compliance with UK building regulations. Ideal for larger residential new builds or retrofits, it supports sustainable heating with minimal maintenance and low thermal mass for faster heat-up times.

Key Features

• Duplex stainless steel: High-grade material for durability and corrosion resistance.
• Pre-plumbed design: Factory-fitted with pump, expansion vessel, and safety valves for rapid installation.
• Unvented mains pressure: Provides high-flow hot water for multiple outlets.
• Heat pump optimised: Low thermal mass for faster heat-up and better efficiency.
• Compact design: Space-saving for utility rooms or cupboards.
• WRAS approved: Certified for potable water systems.
• Integrated coil: High-surface area for efficient heat transfer.
• 10-year warranty: On cylinder body for long-term reliability.

Technical Specifications

• Model: STEELPP250 – STEELflow Heat Pump Pre-Plumbed Cylinder.
• Capacity: 250 litres.
• Material: Duplex stainless steel.
• Maximum pressure: 3 bar.
• Maximum temperature: 65 °C.
• Insulation: 50mm CFC-free foam.
• Connections: 22mm primary coil, 15mm secondary.
• Certifications: WRAS approved, UKCA marked.

Dimensions & Weights

• Diameter: 550 mm.
• Height: 1960 mm.
• Weight (empty): ~45 kg.
• Weight (full): ~295 kg.

System & Application Notes

• Ideal for air or ground source heat pumps in larger residential systems.
• Compatible with most heat pump brands; pre-plumbed for immediate use.
• Suitable for new builds and retrofits; optimises low-temperature systems.
• Installation by qualified plumbers following McDonald guidelines; G3 unvented certification required.
• Enhances efficiency with pre-plumbed setup; 10-year cylinder warranty, 2-year on components.