Preparation
There is published guidance available to help you determine what your key considerations should be:
- BSRIA BG29-2021 “Pre-commissioning Cleaning of Pipework Systems”
- BS 8552-2012 “Sampling and monitoring of water from building services closed systems. Code of Practice.
- BSRIA BG50-2021 “Water Treatment for Closed Heating and Cooling Systems”
Establish the condition of the existing system
Before any physical connection is made you should assess whether the existing system is clean and suitable to connect to. Review the water treatment regime, historic chemical and bacterial analysis results, make-up water usage, and inhibitor levels along with any ongoing remedial concerns. Analysis should be carried out so that locations tested are representative of the system, rather than from just a single point, you may also wish to instruct additional sampling at points local to where the connection will take place.
Decide whether the new section is to be connected directly or requires mechanical separation
If it is determined impractical to connect the new pipework due to the age or condition of the existing system, it may be advisable to mechanically separate the new section of pipework using a plate heat exchanger. This ensures that the existing system water quality cannot adversely affect the newly installed pipework and terminal units and can help with meeting warranty/guarantee standards. However, the new tertiary system will require its own means of pressurisation, dosing, and circulation. It will also require separate ongoing monitoring.
Pre-commission cleaning of the new section
Pre-commission cleaning is the process of getting a closed water system into a satisfactory state for commissioning and ongoing use. For a new section of an existing system, the aim is the same: remove installation debris, reduce suspended solids, control microbiological contamination and leave the new section compatible with the existing system. After cleaning and flushing works you should confirm good water quality through chemical and bacterial analysis of the new system. Ideally, circulation should be maintained throughout the process with the use of temporary pumps if necessary to avoid stagnation and the new section deteriorating between commissioning and connection.
Practical checklist before connection
- Has the existing system been sampled and assessed before the works?
- Is the new pipework clean, flushed, and compatible with the existing system’s water treatment regime?
- Has oxygen ingress been minimised through controlled filling, venting and pressurisation?
- Are the proposed water treatment chemicals suitable for the system metals, seals, and operating temperatures?
- Has a post-connection monitoring plan been agreed, with clear responsibilities and acceptance criteria?
Connection
If a direct means of connection is decided and both the existing system and the new section have produced acceptable chemical and bacterial results, then connection should be carried out quickly to avoid the new section deteriorating in any way.
Monitor and maintain records
After connection, the system should be treated as being in a higher-risk transition period. Take post-connection samples, compare them with the pre-works baseline and trend results over time rather than relying on a single pass or fail result. Re-check strainers and filters for any significant build-up. You may also want to confirm satisfactory flow rates. Any additional water consumption should be recorded, and inhibitor levels should be verified to ensure they have not become diluted. Now is a good time to update your existing operations and maintenance manuals to include the new parts of the system.
This guide is of a general nature; specific advice can be obtained from Assurity Consulting.
Assurity Consulting is the UK's leading independent compliance consultancy specialising in workplace health, safety and environmental solutions. We have over 40 years' experience of helping customers of all sizes, from across all sectors, manage their compliance responsibilities, making sure that their organisation is compliant, their employees are safe, their processes are cost effective and their management team is in control.
