System Power Flush

🔹 Building Regulations & Water Quality in Heating Systems

1. Building Regulations Part L (England & Wales)

• Requirement: All new and replacement wet central heating systems (and boilers) must be cleaned and protected.

• Key points:

• Pre-commission cleaning: Before commissioning, systems should be thoroughly flushed to remove debris, flux residues, sludge, and installation dirt.

• Inhibitor: Systems must be treated with an appropriate chemical corrosion and scale inhibitor that meets BS 7593:2019.

• Water testing: Ongoing checks of water quality are recommended (pH, inhibitor levels, clarity).

• Protection devices: For new/replacement boilers, a permanent filter (e.g. magnetic filter) should be fitted where practical.

⸻

2. BS 7593:2019 (Code of Practice for Water Treatment in Domestic Heating Systems)

Although not law itself, this is the standard referenced in Building Regs & by manufacturers.

• Flushing & cleaning: Mandatory when installing or replacing a boiler.

• Inhibitor: Must be added to the system.

• Filters: Strongly recommended.

• Annual check: Water quality should be checked yearly (similar to a service).

• Refill inhibitor: Every 5 years (or sooner if test shows it’s depleted).

• Record keeping: Homeowner should be given documentation of cleaning, treatment, and checks.

⸻

3. Manufacturer Requirements

• Most boiler manufacturers (Vaillant, Worcester, Ideal, Baxi etc.) require:

• Flush & dose with inhibitor.

• Magnetic filter fitted (warranty condition in many cases).

• If water quality is poor, they can void the warranty.

⸻

🔹 Summary (Plain English for Homeowners / Landlords)

• When fitting a new boiler: The system must be flushed, cleaned, and protected with inhibitor.

• A filter should be fitted to catch sludge.

• Water must be tested and maintained annually to keep efficiency high.

• If not done: Efficiency drops, parts corrode, and warranties may be void.