BG29 (Pre-Commission Cleaning of Pipework Systems) sets out best practice for cleaning commercial heating and cooling pipework before it is handed over.

When new systems are installed, they contain:

Mill scale from steel pipework

Jointing compounds and flux residues

Installation debris

Construction dust and particulates

If not properly removed, these contaminants:

Block strainers and control valves

Damage pumps

Reduce heat exchanger efficiency & accelerate corrosion

BG29 ensures systems are thoroughly flushed, cleaned (mechanically and chemically where required), and verified before commissioning.

In simple terms:

BG29 makes sure your heating system starts life clean — not contaminated.

Skipping or rushing this stage often leads to years of ongoing problems.

What Is BSRIA BG50?

While BG29 focuses on pre-commission cleaning, BG50 (Water Treatment for Closed Heating and Cooling Systems) covers ongoing water quality management throughout the system’s life.

Even a perfectly cleaned system will deteriorate without control of:

Corrosion

Oxygen ingress

Sludge (magnetite) formation

Scale

Microbiological fouling

BG50 provides guidance on:

Water chemistry management

Inhibitor dosing

Filtration and solids removal

Monitoring and sampling regimes

Fill water assessment

Oxygen control strategies

It recognises that closed systems are not “fit and forget” — they require structured monitoring.

Why Closed Heating Systems Fail

Most failures can be traced back to five common issues:

1. Oxygen Ingress

Closed systems should not continually draw in fresh water.

Frequent top-ups introduce oxygen, which accelerates corrosion and magnetite formation.

Automatic filling loops can mask underlying leaks — slowly damaging the system.

2. Poor Water Chemistry Control

If inhibitor levels drop or pH drifts out of range:

Steel corrodes

Copper becomes unstable

Aluminium components can be damaged

Sludge accumulates

Without testing, this often goes unnoticed.

3. No Monitoring Programme

BSRIA guidance aligns with BS 8552, which emphasises routine sampling and analysis.

You cannot manage what you don’t measure.

Typical monitored parameters include:

pH

Conductivity

Inhibitor residual levels

Iron levels

Suspended solids

Make-up water trends

Trend analysis is key — not just “pass or fail.”

4. Inadequate Filtration

Modern heating systems have smaller waterways and more sensitive components.

Magnetic filtration and sidestream filtration are often essential to:

Capture magnetite

Prevent plate heat exchanger fouling

Protect pumps and valves

5. Incorrect Fill Water

Mains water may contain:

High hardness

Elevated chlorides or sulphates

Dissolved solids

In some systems, pre-treatment (softening or demineralisation) may be required to prevent long-term damage.

A properly managed commercial heating system should have:

✔ Documented BG29 cleaning records

✔ Evidence of chemical dosing and stabilisation at handover

✔ A defined water treatment specification

✔ Regular sampling regime

✔ Make-up water monitoring

✔ Filtration strategy

✔ Clear responsibility for water quality management

If these elements are missing, risk increases significantly.

The Business Impact of Poor Water Quality

Failure to maintain water quality can result in:

Increased energy consumption

Boiler inefficiency

Plate heat exchanger fouling

Pump failures

Blocked control valves

Emergency shutdowns

Expensive system flushing or component replacement

In severe cases, entire systems require chemical cleaning years after installation — something that should have been prevented at handover.

The Long-Term Value of Proper Water Treatment

Implementing BG29 and BG50 guidance:

Protects capital plant

Extends system lifespan

Maintains energy efficiency

Reduces reactive maintenance

Supports warranty compliance

Demonstrates due diligence

For building owners and facilities managers, this is about asset protection and cost control — not just compliance.

Final Thoughts

Closed heating systems are often assumed to be low-risk compared to cooling towers or domestic water systems. In reality, they can quietly deteriorate if not managed correctly.

BSRIA guidance provides a structured, lifecycle approach:

Clean it properly (BG29).

Control it correctly (BG50).

Monitor it consistently.

When these principles are followed, closed systems operate efficiently and reliably for many years.