Part L Guide to BS 7593:2019

The new British standard BS 7593:2019 is a code of practice for the preparation, commissioning and maintenance of domestic central heating and cooling water systems. It applies to individual domestic premises when commissioning a system for the first time on a new build, or re-commissioning following the installation of a new boiler, or any other remedial work. The guidance not only covers boilers, but also includes individual heating circuits within blocks of flats, heat interface units (HIU) and wet cooling systems too. 

Why are the regs changing?

The British Standards Institute has been listening to evidence from the industry to ensure its guidance is fit for purpose. By introducing regular testing and re-dosing, proper system cleaning and the mandatory installation of an in-line filter to the industry’s code pf practice, can significantly improve the efficiency and life expectancy of every household system. 

What specific installations does it apply to?

The 2006 edition only covered closed-loop heating systems, this has now been extended to, not only cover closed-loop heating systems, but also to cover closed-loop chilling systems. And in addition to that, the secondary side of district heating systems, so from the point where the heat comes into the apartment, it covers all domestic installations. 

Do systems have to be chemically treated?

Under this new revision of the standard, there’s a requirement to test the system water throughout the life of the heating system. You start this at commissioning and test the water to make sure that the water is now clean, and that you’ve added adequate levels of inhibitor, every year, at the same time that you would do your annual boiler check. You now need to do an annual system water check and re-dose the whole system at five-year intervals (or running a lab test to assess the quality of the water). This is another opportunity to enhance the relationship with homeowners. 

NI regulations are currently running on the 2003 version and will be amended to the 2019 version in the middle of this year.

How to comply with BS 7593:2019

You simply need to follow a six step Best Practice approach to water treatment. 

Step 1 – Clean: add a cleaner and allow it to circulate, so it lifts up all of the debris within the heating system. 

Step 2 – System Flush: Flush the dirty water out. You can do that using products such as the MagnaCleanse or power flush. 

Step 3 – Install Magnetic Filter: Make sure you’ve got an in-line filter fitted and this is a good time to clean and maintain it, such as Magnaclean or TF1. 

Step 4 – Protect: Add your inhibitor and allow it to circulate. 

Step 5 – Test: Test the inhibitor level using a standard inhibitor test such as ProCheck or inhibitor quick test. 

Step 6 – Maintain: You need to maintain the system and you can do that with an annual inhibitor test, and every five years, either a full laboratory test, or a re-dose of the inhibitor.