The latest generation of gas water heaters are highly efficient, with burner, heat exchanger and flue gas management technology maximising energy use for lower emissions of CO2 and NOx, and they also offer a stratagem should the UK opt to embrace a national green gas grid. Expectations for a national hydrogen network, should it proceed, would see a full transition in the 2040s, which aligns with end-of-life decisions for new appliances installed now. The current generation of gas water heaters also offers an out-of-the-box capability to use 20% hydrogen blends, which is likely the first stage of regional hydrogen transition. So, the technology provides a bridge to next-generation sustainable hot water in commercial buildings.
When selecting a gas water heater for your project there are always key considerations around installation, such as access, space, pipework and flueing, but the real defining challenge is addressing water quality at site. The UK presents a varied picture of soft (>100ppm of dissolved calcium and magnesium) to hard water (<280ppm) areas. As water in a commercial hot water system heats up, the solubility of calcium and magnesium bicarbonates decreases, triggering limescale formation in hard water areas which can wreak havoc on the water heater’s efficiency, longevity, and overall performance countering heating and sustainability strategies.
Optimised system design which minimises areas of low flow and stagnation zones and regular system maintenance, including flushing and cleaning and treating with water softeners is crucial in helping prevent excessive scale accumulation. Cleaning and treatment is aided by the use of glass-lined carbon steel water heaters and tanks such as the BFC and Innovo models offered by Adveco. With dual glass lining treatment which bonds to the steel cylinder and forms a smooth protective surface in contact with the water they are lower in cost to purchase, easy to clean and, given the right conditions, provided resistance to attack from most chemicals and corrosive materials.
Not all glass-lining processes though are equal, with some being prone to developing microscopic cracks leading to small areas of the steel cylinder shell being exposed to the water. This is less of an issue in hard water areas, but where the water is softer there is an opportunity for corrosion to rapidly take hold leading to critical failure. Galvanic corrosion in water heaters and tanks is typically managed using cathodic anodes made of magnesium or powered anodes of titanium. However, in many soft water areas, a powered anode may still not have a protective effect, since the conductivity required of the water by the anode is too poor.
For this reason, commercial hot water systems in Scotland, south-west and north-west of England and the west of Wales where water is particularly soft will typically need to employ a stainless-steel appliance such Adveco’s AD and ADplus ranges of compact condensing gas water heaters. Better able to stand up to both waterside and combustion-side assaults, these stainless-steel water heaters are less susceptible to corrosion due to a protective oxide barrier on the waterside that naturally helps prevents corrosion, even when temperatures increase. Able to withstand higher temperature water (in excess of 80°C) than glass-lined appliances, stainless-steel also lends itself to solar thermal applications which can achieve high, consistent water temperature in the summer months.
By adding solar thermal to a gas-fired system you unlock a hybrid approach which will blend improved carbon savings with lower operational costs. Used to generate preheat this approach maximises the efficiency of the technologies involved, creating water temperatures of at least 50°C. Not enough alone for safe legionella-free operation (especially when days are shorter), but when combined with a gas-fired primary heat source, it can be used to raise final temperatures to a necessary 65°C as well as meet peak demands and exceptional requirements for hot water. A true renewable and intrinsically safe to operate, solar thermal technology is designed to use gravity feed, aided by a small water pump for minimal operational energy demands and robust operation. Using far less space for collectors than photo-voltaic solar systems, solar thermal is the optimal low-carbon technology for water heating, capable of offsetting at least 30% of annual system energy demands. As well as active carbon reduction, current cost savings from solar thermal installation mean the technology offers one of the fastest returns on investment for sustainable hot water in commercial environments.
Adveco has current stock of glass-lined and stainless steel gas water heaters, as well as the UK’s widest range of cylinders, plus solar thermal collectors and protective drain back systems and can support orders now for summer project deliveries.
www.adveco.co