The Path to Low Carbon Hot Water

When it comes to tracing a path to low carbon hot water, the design of applications for commercial hot water systems has remained remarkably consistent and if a building is more than ten years old it is going to be built around either a condensing gas water heater or an indirect water heater and boiler. Gas-based hot water systems were specified because this was the most cost-effective and cleanest way of producing high-temperature hot water.

In the past decade though we have seen a seismic shift in thinking driven by the wide acceptance of the harmful effects of global warming and a need to address its root causes. This solidified with the introduction of the Climate Change Act in 2008, and the subsequent drive to make the UK net zero by 2050. With the resultant closure of coal-fired power stations and increasing dependence on wind and solar, the carbon intensity of grid electricity has reduced in line with gas, which has, in turn, remained relatively static since the 1990s.

With the Government’s aggressive new Net Zero Strategy, despite similar carbon intensities for heating from either gas or electric, the latest regulations as outlined in the Heat & Buildings Strategy will deem gas systems alone to be too carbon polluting in commercial-scale buildings. So what path to low carbon hot water can you take? To decarbonise domestic hot water (DHW) applications there are currently two core technology options, air source heat pumps (ASHP) or solar thermal. Although both can provide low or zero-carbon heat, neither can fully replace an existing water heating system. Since commercial DHW systems must operate in excess of 60°C to prevent the threat of legionella, ASHP efficiency, designed to work with lower temperatures, rapidly falls away limiting supply. Solar thermal on the other hand is limited by the sun’s availability across the year, and it is worth remembering will not provide space heating either. However, both can be used as a source of preheat to reduce energy use. Both will work equally well with after heat provided by either gas or direct electricity.

Choosing the right path to low carbon hot water for your building

For buildings already on gas and that rely on large amounts of DHW – a large proportion of current commercial UK properties – solar preheat is the preferable option. Depending on the site and energy consumption habits, solar thermal will typically provide around 30% of the hot water demand.

For new build properties, the expectation is for specification to default to a mixture of heat pumps and direct electric afterheat. For new commercial builds, consultants are specifying for greater electrical load to account for the additional power demands. This though is a costly addition for legacy properties wanting to introduce electrification for higher demands of hot water and heating.

The electrification of buildings is the most common vision, and one the Government is driving with its aggressive target to achieve 600,000 new heat pump installations every year by 2028. Many of these will be for domestic properties, but a considerable proportion will be expected to be introduced via commercial projects. New DHW systems will predominantly follow this model, taking advantage of heat pump performance efficiencies to create a hybrid approach to deliver pre-heating for as much as 75% of the water in a direct electric system. And with no gas to the building, no local generation of NOₓ and no flue to install this clearly has its advantages. This is certainly why the government is championing this technology as the preferred path to low carbon hot water and heating.

However, this approach does not factor in running costs.  While the grid may have reduced its carbon, its cost per kWh has risen consistently over the past two decades. Gas prices on the other hand have remained essentially static until the latter quarter of 2021.  Of course, a proportion of the grid electricity is still generated by gas-fired power stations, so electricity charges also spike in response to any upward fluctuation in gas price. Despite the ASHP performance efficiencies, this has meant the running costs still increase approximately three times due to the difference in current gas/electric prices. For smaller hot water demands in new builds, where the need for a gas supply has been avoided, that additional cost may be acceptable. And we certainly see larger organisations faced with ESOS audits and SECR reporting be willing to absorb the increased running costs to introduce sustainability into their properties as a part of their corporate net zero policy.

Commercial sites with existing gas should really look at continuing to use it. Ten years ago, it was very difficult to argue for introducing solar thermal because the numbers really did not stack up against the price of gas. The capital costs of installation and maintenance versus the operational savings meant many early projects failed to recoup their investment, even with the support of RHI.

Today we are in a very different situation, and if electrical costs can be offset, then the numbers really start to look favourable for adopting solar thermal. A ten-year return on investment becomes very achievable and the property gains undisputed carbon and cost savings. Additionally, the current generation of condensing gas water heaters incorporate features such as flow regulation to automatically optimise the supplied output from the heat exchangers ensuring maximum efficiency. Models with multiple integrated heat exchangers offer load balancing for optimal long-life operation and inbuilt redundancy guaranteeing continuity of service. Those offering titanium-stabilised stainless-steel construction are also highly resilient; meaning warranties on the heat exchanger and burner components can be as much as a decade and operational lifespan should easily be 15+ years. That places replacement well into the early to mid-2030s and that is important because it means gas infrastructure remains in place for adaption to the next generation of hydrogen-based gas supply. The Government expects this will be a core component for meeting net zero at a national level, especially for buildings with higher energy demands. With hydrogen policy to be confirmed in 2026, retaining gas in existing commercial buildings keeps options open and future-proofs a building for other emerging heating technologies.

While we must all recognise the importance of excluding fossil fuels from future commercial systems and advocate all-electric systems for new builds, it is important to understand the implicit costs and difficulties of retrofit and replacement of systems throughout the thousands of legacy commercial buildings that define the UK’s urban landscape. The hybrid approach is unavoidable for commercial projects seeking a path to low carbon hot water and is the most sensible, practical, and cost-effective option. Whether all-electric or using gas after heat, commercial organisations can actively drive sustainability and retain control of operational expenditure for decades to come.

Adveco Named Double Finalist in 2021 HVR Awards

  • Packaged e32 Hot Water Systems named finalist in the HVR 2021 Commercial Heating Product of the Year category
  • FPI32 named finalist in the HVR 2021 Heat Pump Product of the Year category

Hot water and heating specialist Adveco is proud to announce it has been named a finalist in two key categories in the 2021 Heating & Ventilation Review (HVR) Awards. Adveco’s Packaged e32 Hot Water Systems has been named a finalist in the HVR 2021 Commercial Heating Product of the Year category, while the FPi32 range of air source heat pumps (ASHP) was named a finalist in the Heat Pump Product of the Year category.

The HVR Awards celebrate the products, brands, businesses and people that have led the way with their innovation and unrivalled levels of excellence, inducting them into the prestigious HVR Awards ‘Hall of Flame’.

Bill Sinclair, technical director, Adveco, said:

“Both products take full advantage of using R32 refrigerant to take us toward responsible, sustainable systems that deliver business-critical hot water without harming the environment.”

The Adveco FPi32 is a range of compact monobloc design 6, 9 & 12 kW air to water heat pumps providing hot water at 55°C, or higher in hybrid systems. The FPi32 range leverages R32 refrigerant to enhance year-round efficiency (COP as high as 5.23) while reducing the global warming potential (GWP), thereby lowing environmental impact.

The FPi32-9’s compact monobloc form factor also makes it perfect for integration into Adveco’s Packaged e32-Hot Water System.  A complete, highly efficient, low carbon, all-electric packaged water heating system that uses the FPi32-9 to provide preheat for reliable high-temperature water supplied in a convenient GRP housing.

The air to water heat pump provides the system preheat from 10°C to 50°C, supplying 70% of the DHW load. Offsetting 70% of the energy requirement means the Packaged e32-Hot Water System can demonstrate a 47% reduction in energy demands and CO² emissions for the same output of 500,000 litres of hot water each year when compared with a similar direct electric-only system. The reduced energy demand also means operational savings can be added to the capital savings secured during the design, supply, and installation phases.

The system is also ground-breaking in the application of a completely new specification that lowers the heat intensity, without detrimental effect to the demands for hot water, meaning the Packaged e32-Hot Water System is also more resistant to scale, reducing maintenance demands.

“By unifying innovative, low carbon technology with excellence in application design, all provisioned under an offsite construction model, we can bring a wealth of new advantages for consultants, contractors, installers and owner-operators. FPi32 and our pre-sized e32-Hot Water System not only go a long way towards helping businesses meet carbon targets this decade but also help keep running costs low,”

adds Bill.

The 2021 HVR Awards winners will be announced in a virtual presentation on Oct 7th. For more details visit the HVR Awards website.

Adveco commercial heating and hot water systems.Speak to Adveco for all your commercial hot water and air source heat pump requirements. packaged plant rooms. or even our solar thermal solutions.

Call us on 01252 551 540 or see other options on our contact page.

Non-domestic RHI Gains 12–month Extension

Originally set to finish at the end of March 2021, and in response to delays caused to building projects by COVID-19, the Government’s non-domestic Renewable Heat Incentive (RHI) has received a 12-month extension. In response to concerns raised by stakeholders that a significant number of existing projects would fail to meet the scheme closure application deadline of 31st March 2021, affected projects are now able to submit an extension application.

Those existing projects unable to commission and accredit to the scheme before the previous deadline now can extend these processes until 31 March 2022.

With increasing pressure to decarbonise in line with the Government’s ambitious net zero targets, the preservation of reliable and continued funding for the commercial sector is critical if organisations are to be further encouraged in the adoption of future-proof sustainable developments. With no clear, immediate replacement for the RHI, concerns had been raised regarding the lack of incentivisation for the commercial sector, as new schemes focussed on domestic installations. Given around 40% of UK greenhouse gas emissions are accounted for by heating, cooling, ventilation, the provision of hot water and lighting the built environment, and some 17% is generated by commercial building stock, it is clear that more help is required to drive the uptake of renewables and more sustainable systems if the UK is to achieve climate-neutral buildings by 2050.

Designed to provide financial incentives to increase the uptake of renewable heat by businesses, the public sector and non-profit organisations, the non-domestic RHI is currently applicable to air source heat pumps, such as the Adveco FPi range and L70, and solar thermal for commercial uses including large and small businesses, plus schools and hospitals. Administrated by Ofgem on behalf of the Department of Energy and Climate Change (DECC), tier one of the RHI incentivises non-domestic energy producers for either the life of the installation or 20 years as a maximum. If conditions are met, with equipment, including a generation meter, being installed by a microgeneration certification scheme (MCS) accredited installer, eligible businesses in England, Scotland and Wales will now continue to be paid for installations completed and commissioned before 2022.

Once successfully accredited, systems will receive quarterly payments per kilowatt-hour (kWth) of energy use, however, if metered as a multiple system, which includes either ASHP or solar thermal and a gas boiler, then payment is made purely for the heat generated by the heat pump or solar thermal aspect of the application.

The current 2020/21 (non-domestic) tariff are:

  • For new air source heat pumps – 2.79(p/kWh)*
  • For new solar thermal collectors less than 200kWth in size (tier 1) – 10.98(p/kWh)*

For specifiers and developers installing renewable heating systems on commercial buildings or small-to-medium-scale district heating projects, the extension also provides crucial financial support ahead of the Green Heat Network Scheme (GHNS) coming into force in April 2022.

*For more information on non-domestic RHI and the full conditions of eligibility, refer to the energy regulator Ofgem.

Making ASHP Work For Commercial Applications – Part 1

Understanding the Challenge of Air Source Heat Pumps (ASHP)

Commercial organisations face a somewhat unfair challenge as they are held by the Government to be leaders in the move to control and reduce carbon to achieve net-zero by 2050, yet are limited by the technology options that the Government is showing active support for. The current drive, without a doubt is to push Air Source Heat Pumps (ASHP) to the exclusion of other technologies. Neither high-efficiency gas boilers with ultra-low emissions nor proven sustainable systems such as solar thermal have received much love in the latest round of grants supporting the commercial sector. In particular, the decision not to provide support for those opting for hybrid solutions that bridge the technology gap in the most cost-effective manner shows a focus on the finish line, but a failure to grasp the actual challenges the commercial sector faces right now. So, what are the options with ASHPs, and what is a realistic path to take today?

Unfortunately, we cannot control the weather, but despite that, ASHP technology does still present an opportunity to significantly improve the efficiency of buildings across the commercial sector. Because an Air Source Heat Pump is reliant on the ambient air, the Coefficient of Performance, or COP, is going to be affected by both the source and supply temperatures. The heat provided is at a much lower temperature, so a heating system will be required to operate at low temperature for optimum efficiency and may have to be kept on for a longer period to be fully effective. Such a system could well require a significant upgrade to a building’s electrical supply and heating infrastructure. However, to maximise the ASHP efficiency, the lowest possible flow temperature needs to be achieved, and that requires a building to be highly efficient in terms of heat loss. When working with new builds, the ability to drive high efficiency in the thermal performance of the fabric of a structure means a well-designed commercial heat pump system is more than capable of providing all the heating needs for a business and, in the long term, represent good value for money in savings from reduced energy bills, as well as helping commercial premises bring down that all-important carbon footprint.

But in isolation, this demand for low heating temperatures and low water usage will be impractical for many businesses, especially when retrofitting a property, which can highlight the limitations of ‘pure’ ASHP systems. This becomes particularly obvious when ASHP is to be deployed for the provision of hot water, especially if there is a large daily demand. Domestically we would expect a minimum storage temperature of 50oC, but this rises to 60oC minimum for commercial environments. This has a considerable impact on the ASHP’s running efficiency and therefore the running costs. Additionally, by generating hot water at 50oC and not 70oC, the storage volume will have to be considerably larger than that associated with a typical gas boiler. To achieve necessary water temperatures requires greater considerations of space planning and type of hot water cylinder the system will require.

With early to market performance of heat pumps falling below expectations, and a higher capital cost relative to the conventional gas boiler alternative the uptake of ASHP in commercial business on the gas grid had, until the drive to achieve net-zero, been limited. Now commercial operations are actively seeking to use commercial ASHP, but are still running up against these same issues, which is why, with the current capabilities of ASHP technology, a hybrid approach for commercial applications remains attractive. Both in terms of installation and operation, whilst still gaining the all-important running cost savings and reduced carbon emissions.

In part 2 we explore how a hybrid approach can deliver significant value from commercial ASHP technology

Read about Adveco’s compact commercial FPi ASHP range

SSI 1500 Stainless Steel Indirect

Is a Calorifier Right for My Project?

A calorifier is a commercial-grade indirect-fired water heater that provides hot water in a heating and hot water system.

It is designed for projects requiring large volume storage of water at high temperature, but rather than using a burner, the water is heated by heat exchanger coils containing liquid from another heat source, such as a boiler.

In a typical application, the hot water directly heated by a gas or electric boiler passes through the calorifier and is used, via heat exchange, to heat up the cold water in a separate system of pipework. This does mean that a calorifier cannot react as quickly to demand as a direct-fired water heater, however, with the calorifier working as a buffer and storing the hot water, it reduces the operational demand placed on the boiler. With the boiler no longer required to work as hard to meet the domestic hot water needs (DHW) of a building, energy is saved, costs are reduced and emissions fall.

With the increased efficiency of modern condensing gas boilers, having a dedicated hot water boiler to heat the calorifier is no longer a requirement as they can easily supply heat to both the calorifier and the heating system. The compact Adveco MD range of gas condensing boilers, for example,  are both high capacity and can be arranged in cascade to scale to provide both heating and, with an indirect calorifier, the DHW needs of a wide variety of commercial projects. It must be noted that when space heating is not required, such as during the summer months, the boiler will still be required to provide heat for the hot water system.

Another advantage of the indirect approach to heating is that due to the transferral of heat through the walls of the heat exchanger element the two fluids do not mix. This allows for more options in terms of the external heat supply and introduces a range of renewable technologies that use other fluids for heat transfer including solar thermal collectors and Air Source Heat Pumps. At Adveco, these options are supported by a variety of calorifiers. The Stainless Steel Indirect (SSI) range, for example, is supplied with a single high-output internal heat exchange coil at low level to serve as an indirect calorifier in DHW installations. For more complex and renewable-based systems, the Stainless Steel Twin-Coil (SST) range offers a pair of independent internal heat exchange coils to serve DHW systems. Each high-output coil can be used with a separate heat source, enabling effective integration of renewable technologies or multiple heat sources, or alternatively can be combined to increase the heat transfer capacity from a single high-output source.

Also, by separating the supplies you reduce the risks of external contamination, a build-up of scale in hard water areas or the corrosive effects of soft water.

Calorifiers are also simple to install. Since there is no burner, there is no need for the gas supply to be directly connected to the appliance and the is no requirement for a flue.

As with any hot water application, understanding the relationship between storage and recovery, and correct sizing is extremely important for efficient and cost-effective operation. Integrating a calorifier within a hot water system gives you a number of design options, as a larger calorifier means the boiler can be smaller, or the reverse if the existing system has a large efficient boiler. Understanding the hot water demand is critical. If demand is not so great, then using a larger calorifier can lead to unnecessary capital and ongoing operational expenditure. Go too small and the storage could prove inadequate and the system will not achieve its operational requirements.

Attaining the correct balance of demand and efficient, cost-effective supply is what ultimately defines a successful system, whether it be for a hotel, hospital, school, office or leisure facility. Each will have their own parameters to be met, and Adveco specialises in providing the widest range of calorifiers, boilers and renewables to meet the bespoke needs of any project.

The patterns of hot water usage and recognition of periods of peak demands often make sizing a complicated process, with many systems overcompensating and, by being oversized become more costly and less efficient. At its simplest, a commercial system should hold an hour of hot water output in storage, but the function of the building, its population and activities will adjust requirements, for example, where hospitals will typically exhibit a 24/7 demand for hot water, schools and offices may be limited to just 7½ hours per day. In some refurbishment scenarios, we will also see a physical limitation of space available for DHW storage, in which case a system will put more demand on the boiler or renewable to increase the output for preheating, reducing the required size of calorifier.

If there is an availability of space, or a prefabricated packaged plant room approach can be used to relocate plant to previously unused space – such as a rooftop or car park – there is an opportunity to incorporate multiple calorifiers and thereby divide the total storage demand. This approach not only provides system resilience, but for commercial sites that exhibit predictable seasonal demands such as leisure centres, campsites and hotels, it allows for elements of the system to be shut down during off-peak periods. The other real advantage of adopting a packaged plant room approach to a DHW system is that the boiler or ASHP providing the preheat can be located in close association with the calorifier. The physical proximity helps negate problems of heat loss between the boiler, pipework and calorifier which can be detrimental if more widely separated in a system.

Adveco commercial hot water and heating. Discover more about Adveco water heating, water buffers and calorifiers, and how we can help size your DHW application.

Call us on 01252 551 540 or visit the contact us page.

Commercial Air Source Heat Pumps (ASHP).

Adveco Introduces the FPi Range of Commercial Air Source Heat Pumps for Hybrid DHW Systems

  • Delivers above average coefficient of performance to help reduce a building’s energy consumption and reduce operational costs.
  • Perfect for hybrid DHW systems that help meet new carbon targets.
  • Quick and easy to install and then maintain.

Hot water and heating specialist Adveco, in partnership with Italian heating manufacturer Cosmogas, introduces the FPi range of commercial-grade Air Source Heat Pumps (ASHP). The two variants, the FPi-9 and FPi-13, provide excellent levels of performance, especially throughout the UK’s relatively mild winters.

FPi delivers an easy to install method for commercial sites to achieve lower cost water heating or cooling. With sleek looks and quiet operation, the compact monobloc design is capable of providing domestic hot water (DHW) at up to 55°C, or cool water to -7°C for use in fan coils.

Bill Sinclair, technical director, Adveco, says:

“The FPi range of ASHPs is perfect for combining with a traditional gas water heater and controls to create a hybrid system. Offering better compatibility with existing DHW distribution systems and the demands of higher thermal requirements. This approach provides the versatility to reduce operational costs while maintaining the higher water temperatures demanded by commercial DHW operations. A hybrid system built around the FPi can help businesses meet their carbon targets in the coming decade, while keeping running costs low.”

Due to advanced vector control technology that provides an accurate response to variable operational cycles throughout the year, the FPi range is able to achieve an above-average coefficient of performance (COP). Ranging up to a very high COP of 4.7, FPi ASHPs can make a real impact on a property’s energy consumption.

The FPi range is virtually maintenance-free, requiring simple, regular cleaning of the coil and filter. Sensors constantly check pressure and each unit is equipped as standard with frost protection, enabling them to operate effectively with excellent yields even if temperatures drop as low as -25°C.

Technical Information


  FPi-9 FPi-13
Dimensions HxWxD (mm)


753x943x354 1195x1123x400
Weight (kg) 62.5 113
Noise level (dB(A)) 56 59
Max. heating capacity (1) (kW) 10.1 12.6
Max. heating capacity (2) (kW) 9.53 11.5
COP min. / max. (1) 4.02/4.65 3.89/4.7
COP min. / max. (2) 3.12/3.55 2.97/3.28
Circuit max. pressure (bar) 42 42
Rated water flow (L/s) 0.43 0.61


(1) Heating condition: Water in/out temperature 30°C/35°C. Ambient temperature DB/WB 7/6°C.

(2) Heating condition: Water in/out temperature 40°C/45°C. Ambient temperature DB/WB 7/6°C.