As we approach the one-year mark since revisions to the approved Document L of England Building Regulations were introduced, we’ve seen a significant step towards more energy-efficient DHW heating products in commercial buildings. This change is the result of the installation of direct oil-fired or gas-fired non-condensing water heaters being phased out and replaced by condensing water heaters. While condensing water heaters aren’t new on the scene, the latest regulations have certainly thrust their benefits into the spotlight.

Improved energy efficiency

Since June 15th, 2022, direct-fired water heaters in England must have a minimum heat generator seasonal efficiency of 91% GCV (gross calorific value) for natural gas and 92% for LPG (liquefied petroleum gas). For indirect water heaters, the minimum heat generator seasonal efficiency is set at 91% for both natural gas and LPG. However, it is worth noting that the ‘seasonal efficiency’ for direct-fired products is measured according to the product standard that it has been manufactured to. For most dedicated water heaters with storage, this is most likely to be BS EN 89 and is referred to within this standard simply as ‘efficiency’.

Out with the old, in with the new

These tighter standards apply to both existing and newly constructed non-domestic building stock and effectively eliminate the possibility of replacing non-condensing water heaters with like-for-like models, exceptional circumstances permitting. 

Here, where condensing water heater replacement is deemed not suitable or practical by the Building Control Body, a minimum seasonal efficiency of 80% for gas, or 79% for LPG will apply.

This increase in minimum hot water heating efficiency is part of the government’s plan to reach its net zero goal by 2050, and it represents a significant step towards more energy-efficient water heating in non-domestic buildings.

By now, we should all be up to date on the benefits of condensing direct-fired water heaters but let’s have a quick refresh. Unlike non-condensing varieties, condensing units can capture and reuse latent heat that is otherwise lost to the atmosphere. As a result, they are up to 20% more efficient than non-condensing models.  

Furthermore, in line with the current ErP requirements which state that water heaters must operate under specific NOx (nitrate oxide) thresholds of 56 mg/kWh for a single appliance, condensing water heaters contribute fewer emissions to the environment, making them a more sustainable choice in new build premises and building refurbishments.  

The solution

The good news is that units such as the Hamworthy Dorchester DR-SG range of stainless steel condensing water heaters can achieve maximum efficiencies (EN89) of up to 95.5%, providing a safety net should regulations tighten in the future.

Furthermore, with NOx emissions under 40 mg/kWh across the range (Class 6), the Dorchester DR-SG significantly exceeds the latest minimum efficiency thresholds required for Part L2 compliance.

Direct-fired water heaters such as the Dorchester DR-SG provide an efficient and cost-effective means of delivering huge volumes of hygienic hot water around buildings that have high peak demands. Suitable for both renovation and new build projects, such as hotels and sports facilities, the Dorchester DR-SG meets all the latest Building Regulations and offers significantly improved efficiency and performance when replacing a non-condensing water heater. 

For more information on our Dorchester visit here or download our brochure.