Power Flush for Commercial Buildings

Over time, your central heating system will collect sludge and iron oxide (rust) in the pipework, interfering with the system’s functionality. A power flush is a routine maintenance procedure that improves the efficiency of central heating systems.

In this guide, we’ll go over signs that it’s time for your commercial property to get a power flush. Head over to our heating and plumbing service page if you would like an assessment of your commercial heating system or if you have any questions regarding a power flush.

What is a Power Flush?

Power flushes use high-flow, low-pressure water to gently remove the debris without damaging the pipework. If not cleaned, the system will have to work harder to produce the same amount of heat, driving up energy costs and potentially causing lasting damage.

Commercial water-based heating systems need power flushes more often than smaller systems. This is because they often rely on water traveling at a high velocity over much longer distances. This degrades metal surfaces faster, which increases the risk of rust forming quickly.

Regardless of the pipework material of your commercial heating system, most of the rust comes from system components made from mild steels, like radiators and plate heat exchangers. The more complex the system, the more often it needs to be flushed.

A process often confused with power flushing is a chemical flush. A chemical flush relies on the system’s existing pumps and gravity to transport chemicals throughout the system. A power flush is more effective as it uses a pump, which allows for a more thorough clean of the nooks and crannies of a heating system that are hard to access. It also rarely requires water to be drained from the heating system, while a chemical flush always requires it.

Is a Power Flush Needed for My Commercial Central Heating System?

If your heating system isn’t functioning correctly, your business can suffer – especially around the winter months. Problems with temperature control can make employees and customers uncomfortable, and drive up energy costs.

There are a variety of reasons that we might suggest a power flush for your business, but typical signs include:

Radiators that are slow to heat up (particularly at the top and bottom)
Radiators with cold spots
Boiler cut-outs from pump failures or potential blockages in the main flow or return pipework
Excessive noise from your boiler
Discoloured water when bleeding the system
Any visible signs of rust or corrosion on the outside of the system
Noticeable system inefficiencies
A decrease in performance over time

At Akehurst, we often recommend a power flush before installing a new heating system to remove debris collected during manufacturing. The Building Services Research and Intelligence Association (BSRIA) released updated guidance on pre-commission cleaning of pipework systems in 2021. Our heating and plumbing services always follow the best practices established in BSRIA 29, which will ensure that your system is well-cleaned and ready to go.

How Can a Power Flush Benefit My Business?

Power flushing your commercial heating system improves the system’s energy efficiency, reducing your energy bills. The system will last longer, be less likely to need expensive repairs, work more efficiently (heat up faster and run quieter) and be able to reach higher temperatures. A well-working central heating system is essential for a productive and comfortable work environment.

Most commercial heating systems are closed-loop, which means the system is sealed. A system must be sealed to carry out a power flush; a vented (unsealed) system would overflow when water is added. The solution is to drain some water so that the expansion vessel doesn’t overflow. However, as most commercial heating systems are sealed, this is rarely a concern.

Some system components are more likely to generate rust and sludge. If your system has any of the following components, it’s likely to benefit from a power flush:

Plate heat exchangers
Commercial boilers (e.g., oil and gas boilers, LPG boilers, steam boilers)
Water-based underfloor heating (particularly if there are cold spots)
Heat interface units (particularly for offices / large residential buildings with zonal heat systems)

Sludge build-up can reduce heating system efficiency by up to 15%.

British Heating and Plumbing Magazine

The Power Flush Process

Typically, a power flush for a commercial heating system follows these 7 steps:

Pre-Assessment: When power flushing a commercial heating system, a thorough assessment of the building and the power flush process must be conducted to ensure a safe, effective clean. If there are chemicals involved that fall under the Control of Substances Hazardous to Health (COSHH) regulations, then a full risk assessment must be completed.
Chemical Pre-treatment: In cases with significant sludge and rust build-up, chemical pre-treatment is used to break down large deposits of accumulated sludge, hours or days before the flush.
Preparation: Before starting a power flush the system is checked to ensure it is sealed, and water is drained from the system if it is vented. Next, a high-flow, low-pressure pump is connected to the central heating system at the circulation pump, which is typically found in the plant room / boiler.
Power Flush: The flow of water (and cleaning chemicals if necessary) is introduced to the system to dislodge and remove sludge and rust from the heating system. Extra steps need to be taken when flushing through pumps (even if the pump is off) as the movement of the water can generate an electrical charge, which will feed back to the boiler and could cause a shutdown. If it is possible, the flow of water may be reversed to remove as much sludge and rust as possible.
Cleaning: The system is then rinsed to ensure that sludge, rust and chemical residue has been removed.
Testing and Rebalancing: As part of the final steps, the heating system is tested to ensure that the power flush has successfully removed sludge, rust and other debris, and restored the efficiency of the system. The system is then balanced (checking the water’s flow rate) to ensure that there is an even distribution of heat.
Additional Mitigation: A rust-proof inhibitor, along with filters or strainers can be added to the heating system to reduce future build-up of sludge and rust.

Maintaining System Performance After a Power Flush

Integrating Power Flushing Into Planned Maintenance And Regular Inspections

Power flushing should be part of your company’s planned maintenance, not only used to address a problem. Routine power flushes keep the system working efficiently and help it last longer. At Akehurst, we can provide guidance on what routine maintenance your system might require, including power flushing, testing inhibitors and water quality treatment.

Filtration, Strainers and Magnetic Dirt Separators

After performing a power flush, it’s important to take preventative measures to slow the accumulation of more rust and sludge. This helps protect pipework and components, preventing future damage. Some examples of preventative measures include:

Rust-Proof Inhibitors: Flushed through the system after the power flush to protect metal surfaces from corrosion.
Magnetic Filters: Especially useful for reducing rust, these filters capture and remove small metallic particles from the system.
Strainers: Mesh filters that capture larger debris.
Magnetic Dirt Separators: An attachment that vents trapped air and removes debris. Removing air is particularly important as its presence in the heating system facilitates corrosion.

Conclusion

Power flushing your commercial central heating system is a crucial step to protect one of your building’s vital systems. It improves your heating system’s efficiency, helps prevent larger, more expensive repairs and can cut your energy bills. At Akehurst, our expert team offers power flushing as part of our heating and plumbing services, which includes a full assessment and detailed maintenance plan to keep your staff and customers happy.