In the ever-evolving landscape of sustainable home heating, the integration of high-performance heat pumps with reliable hot water storage solutions stands out as a game-changer. Today, we're delving into the synergy between Riello's NXHM series air source heat pumps and Telford's Tempest indirect cylinders. This post explores why this pairing delivers exceptional efficiency, reliability, and cost savings for British households. Whether you're retrofitting an existing system or installing in a new build, this combination promises optimal performance in heating and domestic hot water (DHW) production.
Understanding Riello NXHM Heat Pumps
Riello, a renowned Italian manufacturer with a strong presence in the UK market, offers the NXHM monobloc air-to-water heat pumps designed for residential and light commercial applications. These units excel in providing heating, cooling, and DHW while prioritising energy efficiency and environmental impact.
Key models range from NXHM 004 to 030, with heating capacities spanning 4.2 kW to 30.1 kW. The smaller single-fan variants (004-016) cater to typical domestic needs, delivering nominal heating outputs from 4.2 kW to 15.9 kW, while the twin-fan models (018-030) handle larger demands up to 30.1 kW. At the heart of these pumps is DC Inverter technology paired with a Twin-Rotary compressor, which modulates output to match demand precisely, reducing energy waste.
Efficiency is a standout feature: Coefficient of Performance (COP) reaches up to 5.1 at A7/W35 conditions (meaning 1 kW of electricity generates 5.1 kW of heat), with values like 4.60 at A7/W35 and 2.85 at A-7/W35 for the 14 kW model. Seasonal COP (SCOP) ratings often achieve A+++ energy class, ensuring compliance with UK building regulations and eligibility for incentives like the Boiler Upgrade Scheme. The units use low-GWP R32 refrigerant (e.g., 1.40 kg in the 6 kW model), support maximum flow temperatures of 65°C, and operate quietly, making them ideal for urban installations.
Installation requirements are straightforward: these monobloc units house all components outdoors, connecting via water pipes to indoor systems. They include built-in controls for seamless integration, with options for hybrid setups alongside boilers. Performance data highlights robust operation in cold climates, maintaining output at -7°C ambient temperatures (e.g., 4.30 kW at W45/A-7 for the 4 kW model).
To learn more about the Riello range, explore our collection at Riello Heat Pumps.
Watch this official introduction from Riello's training series for a deeper dive into the NXHM components and connections:
Exploring Telford Tempest Heat Pump Cylinders
Telford Copper & Stainless Cylinders, a UK-based specialist with over 30 years of expertise, produces the Tempest series specifically tailored for heat pump applications. These unvented stainless steel cylinders (using Duplex 2304 grade for corrosion resistance) are engineered to maximise heat transfer from low-temperature sources like air source heat pumps.
Available in capacities from 90 to 500 litres, the Tempest indirect models feature a large surface area coil (typically 3 m² or more) optimised for heat pumps, ensuring efficient DHW production even at lower flow temperatures (around 55°C). Pre-plumbed variants, such as the Tempest Pre-Plumbed Indirect with a 50L integrated buffer, simplify installation by including components like a 28mm 3-port valve, drain valve, immersion heater, and pre-fitted D1 pipework.
Specifications include high insulation for minimal heat loss (achieving A or B energy ratings: A for 90-200L, B for 250-300L), pressure ratings up to 7 bar (with a 1/2” 7-bar T&P relief valve), and dimensions that fit standard airing cupboards (e.g., 300L model with buffer). The cylinders support indirect heating, with options for solar or twin-coil configurations, and come with a thumb vent for easy maintenance.
Benefits include durability, low standing losses, and compatibility with most heat pump brands, thanks to the purpose-designed coil that enhances heat exchange. This setup allows for rapid reheat times and consistent hot water supply, even in larger households.
For specific products, check out our Telford Tempest Pre-Plumbed Indirect Heat Pump Cylinder with 50L Integrated Buffer - 300L and Telford Pre-Plumbed Indirect Cylinder with 50L Integrated Buffer - 250L.
Why the Riello and Telford Combination Excels
The true magic lies in combining Riello's NXHM heat pumps with Telford's Tempest cylinders. Riello's ability to deliver consistent low-temperature heat aligns perfectly with Telford's high-efficiency coils, optimising energy transfer for DHW. This setup can achieve system COPs exceeding 4.0, translating to significant reductions in running costs compared to traditional gas boilers.
In a typical installation, the Riello unit connects to the Tempest cylinder's indirect coil, using the integrated buffer to manage heating zones efficiently. This prevents short-cycling, enhances system longevity, and ensures stable performance. Compatibility is assured, as Telford's pre-plumbed designs accommodate the majority of heat pumps, including Riello's monobloc systems. Key benefits include:
- Energy Savings: Up to 75% reduction in heating bills through high efficiency.
- Environmental Impact: Lower carbon emissions with R32 refrigerant and renewable heat extraction.
- Reliability: Robust components with warranties (e.g., 25 years on Telford cylinders).
- Ease of Installation: Pre-plumbed features reduce on-site work, with Riello's controls integrating seamlessly.
Real-world case studies, like those from Riello, demonstrate installations achieving SCOPs of 4.5+ when paired with well-insulated cylinders. Watch this official Riello case study for inspiration:
Final Thoughts: Amplifying Savings with Solar Integration
To maximise your energy independence and further slash bills, consider combining this heat pump and cylinder setup with solar photovoltaic (PV) systems. Heat pumps run efficiently on electricity, and pairing them with solar panels allows you to generate your own power, offsetting consumption during peak daylight hours. This can reduce annual heating costs by an additional 30-50%, depending on your location and usage, while qualifying for smart export tariffs.
Discover how solar can transform your setup at our Solar Collections page.