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Rinnai’s Cost Effective and Lower Carbon Hot Water Heating Solution for Surrey Care Home

A large 72 room care home in Surrey with a 123-person occupancy needed to reduce its operational carbon emissions by 20% but maintain a generous hot water supply during peak periods. The owner-operators also needed to re-structure both the operational costs and energy usage.

The Rinnai Design Team sized this commercial care home site by taking into account the peak periods of hot water usage in the morning and early evening. The Rinnai Design Team provided the customer with three options based on the carbon production, energy usage and operational costs. The new options were also compared to the existing, traditional storage system.

The Rinnai Design Team sized this commercial care home site by taking into account the peak periods of hot water usage in the morning and early evening. The Rinnai Design Team provided the customer with three options based on the carbon production, energy usage and operational costs. The new options were also compared  to the existing, traditional storage system.

The options included a Rinnai H1 gas-powered system of three N1600 Continuous Flow Water Heaters. Secondly, a Rinnai H2 hybrid system, made up of two 21kW heat pumps and three continuous flow N1300s. Thirdly a Rinnai H3 all-electric solution that utilizes two 50kW heat pumps and two 48kW E-cylinders.

Over five years the costs of each hot water system were clearly shown:

  • the Rinnai H1 natural gas system is the most cost effective at £52,806.30.
  • the Rinnai H2 hybrid system is at £56,745.84.
  • the Rinnai H3 all electric system amounted to £149,666.32 – The huge gap here is explained by electricity costing around 300% more than gas.

Rinnai’s decarbonising hot water solutions are represented in the colours grey (H3 all electric), orange (H2 hybrid) and blue (H1 natural gas), whilst the currently installed gas system is highlighted in yellow. The first graph demonstrates the operational costs associated with each system.

As reducing 20% of emissions was a key part of the customers ‘must-do’ objectives, all suggested systems are proven to perform to a cleaner standard than the existing traditional system. The Rinnai H1 natural gas, Rinnai H2 hybrid and Rinnai H3 all electric systems offer carbon reductions of 14.9%, 30% and 67.5% respectively.

The following graph depicts the energy savings to be made:

  • the Rinnai H1 natural gas system offers a 14.9% reduction.
  • the Rinnai H2 hybrid system sees a 27.1% reduction.
  • the Rinnai H3 all electrical system yields a 39.7% reduction.

The care home decided that the preferred solution for this particular property would be the H2 hybrid hot water system. The H2 system would offer a reduction in emissions by at least 20%, as well as reducing the initial investment and forecasted operational expenditure by 21.7% and 62.1% respectively, when compared to the H3 all electric system.

Rinnai’s design team offers all UK customers a report and calculations on carbon and cost comparisons to other systems and fuels. For more information on FREE customer services visit Rinnai’s website at:

Rinnai continues to provide UK customers with a variety of low carbon and cost-effective technologies that encourage commercial and domestic decarbonisation. No matter the specific requirements of any site, Rinnai can offer the ideal customer solution.


Rinnai’s H3 range of decarbonising products include hydrogen / BioLPG ready technology, hybrid systems, and a wide range of LOW GWP heat pumps and solar thermal. Also, within Rinnai’s H3 range is Infinity hydrogen blend ready and BioLPG ready continuous flow water heaters which are stacked with a multitude of features that ensure long life, robust & durable use, customer satisfaction and product efficiency.

Rinnai’s range of decarbonising products – H1/H2/H3 – consists of heat pump, solar, hydrogen in any configuration, hybrid formats for either residential or commercial applications. Rinnai’s H3 range of products offer contractors, consultants and end users a range of efficient, robust and affordable decarbonising appliances which create practical, economic and technically feasible solutions. The range covers all forms of fuels and appliances currently available – electric, gas, hydrogen, BioLPG, DME solar thermal, low GWP heat pumps and electric water heaters.

Rinnai H1 continuous water heaters and boilers offer practical and economic decarbonization delivered through technological innovation in hydrogen and renewable liquid gas ready technology.

Rinnai’s H1 option is centred on hydrogen, as it is anticipated that clean hydrogen fuels will become internationally energy market-relevant in the future; Rinnai water heaters are hydrogen 20% blends ready and include the world’s first 100% hydrogen-ready hot water heating technology.

Rinnai H2 – Decarbonization simplified with renewable gas-ready units, Solar Thermal and Heat Pump HybridsRinnai H2 is designed to introduce a practical and low-cost option which may suit specific sites and enable multiple decarbonisation pathways with the addition of high performance.

Rinnai H3 – Low-GWP heat pump technology made easy – Rinnai heat pumps are available for domestic and commercial usage with an extensive range of 4 – 115kW appliances.

Rinnai’s H3 heat pumps utilise R32 refrigerant and have favourable COP and SCOP.

Rinnai is a world leading manufacturer of hot water heaters and produces over two million units a year, operating on each of the five continents. The brand has gained an established reputation for producing products that offer high performance, cost efficiency and extended working lives.

Rinnai’s commercial and domestic continuous flow water heaters offer a limitless supply of instantaneous temperature controlled hot water and all units are designed to align with present and future energy sources. Rinnai condensing water heaters accept either existing fuel or hydrogen gas blends. Rinnai units are also suited for off-grid customers who require LPG and BioLPG or DME.

Rinnai products are UKCA certified, A-rated water efficiency, accessed through multiple fuel options and are available for purchase 24/7, 365 days a year. Any unit can be delivered to any UK site within 24 hours. Rinnai offer carbon and cost comparison services that will calculate financial and carbon savings made when investing in a Rinnai system. Rinnai also provide a system design service that will suggest an appropriate system for the property in question. Rinnai offer comprehensive training courses and technical support in all aspects of the water heating industry including detailed CPD’s. More information can be found on Rinnai’s website and its “Help Me Choose” webpage.


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6 March 2024


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