The choice between direct and indirect water heating systems in commercial buildings depends on various factors, including energy efficiency, cost, space availability, and the specific hot water demand profile of a building. Understanding these advantages and disadvantages allows for more informed decisions tailored to the unique needs of each commercial application…
The challenges of direct water heating
In commercial buildings, direct water heating systems provide hot water on demand by heating water instantly as it flows through the unit, without requiring a storage tank. Direct water heaters, such as tankless or on-demand models, are compact and save valuable space, making them ideal for commercial settings where space is at a premium.
While direct systems offer a continuous supply of hot water, in situations with extremely high and simultaneous hot water demands these heaters can struggle to keep up, potentially requiring multiple units to meet the needs, increasing the costs and complexity of the system. They can also be prone to inconsistent water pressure and flow rates which can preclude them from use in many commercial applications such as taller buildings or locations requiring a guaranteed hot water supply.
Crucially with sustainability climbing the agenda, they are limited to energy sources, being reliant on either electricity or gas. In areas where energy costs are high or where there are restrictions on gas usage such as new builds, operating costs can become problematic. This is on top of upfront costs associated with the units themselves, the specialised knowledge and potentially more extensive modifications to existing infrastructure in retrofit scenarios.
Why choose indirect water heating in commercial buildings?
Compared to direct systems, indirect water heating applications require more installation space and can be complex and costly to set up as they must be integrated with the primary heating system. However, there are far more advantages to be gained by deploying indirect water heating systems in commercial buildings.
Utilising a primary heating source to heat water, which is then stored in a separate tank means indirect systems can provide a large volume of hot water, making them highly effective for commercial applications with high and continuous hot water demands, such as hospitals, hotels, and large office buildings.
Indirect systems typically have fewer moving parts and less direct exposure to mains water, which helps enhance their durability and reduce maintenance needs. This is especially so if investment is made in stainless steel cylinders which are resistant to the corrosive effects of soft water, and with a finite amount of water in the primary heating loop can also be shown to counter the effects of limescale formation in hard water areas.
For buildings with extensive heating needs, indirect water heating systems can be integrated with the building’s existing heating system, such as a boiler, potentially reducing operational costs and enhancing energy efficiency. This approach can be popular in colder climates where the heating system is frequently in use. Should the primary system fail or be turned off, the supply of hot water will be interrupted, which is a significant issue. In the UK Adveco would advise separating heating from hot water whenever possible. Domestic hot water (DHW) in commercial settings requires consistent higher working flows best achieved in separate systems to ensure service delivery and anti-legionella processes.
Where indirect heating applications really shine is through their versatility to integrate with a variety of energy sources that include natural gas and electricity, but also LPG, oil, and more importantly solar thermal and air source heat pumps which reduce carbon emissions and help offset primary heating energy demands. Depending on the available energy infrastructure, indirect heating offers flexibility, greater sustainability and potential cost savings that are especially advantageous to the commercial built environment.
Indirect systems are not without their challenges as the approach generally requires more space due to the need for both a storage tank and a separate heating unit, which leads to more complex and costly installation. Systems may also take longer to heat water than direct systems, even more so when using air source heat pumps, which would be a disadvantage in settings where immediate hot water is needed. For this reason, a building’s hot water design must be as thorough and accurate as possible. Traditionally this would require a completely bespoke approach to every building, today though there are simpler options, especially for small to medium-sized demands, whereby a pre-sized, ready-to-go system can be selected for faster installation. Adveco leads the charge with this pre-built system approach with the award-winning FUSION packaged electric water heating system.
FUSION is a next-generation indirect water heating system for commercial properties. FUSION-E harnesses Adveco’s ARDENT electric boiler and high-pressure ATSI single-coil stainless steel cylinders to deliver a compact, highly efficient, low-carbon electric water heater. FUSION-T adds Adveco’s FPi32 Air Source Heat Pumps, dedicated controls and metering, for further carbon reduction and operational cost savings. With more than 80 variants currently on offer, and the potential to incorporate solar thermal into dual-coil cylinder variants there is a ready-to-go system for most organisations seeking a robust, compact, more sustainable water heating system which harnesses the advantages of indirect water heating.
