From the initial point, a central heating system is filled with water the corrosion process will begin. All central heating systems are constructed of mixed metals such as steel, copper, brass and many others. All these metals touch one another through the medium of water. Water is the catalyst to the corrosion process but is also a key requirement of heating your home efficiently. 

As central heating engineers, one of our roles is to slow this corrosion process down. We do this by adding chemicals to the water column when required either as part of our yearly service and maintenance checks or when we drain down a central heating  system to work on it. You can not stop a heating system from corrosion but you can maintain it.

Unfortunately unlike cars many homeowners blatantly choose not to maintain their boilers and heating system. When problems such as leaks occur many homeowners quickly turn to Youtube or other self-help forums instead of licensed heating engineers. With the power of videos, many homeowners are lured into a false sense of security thinking they can resolve many boiler and heating system issues themselves.

Coupled with a lack of maintaining heating systems and homeowners filling heating systems or continually topping up heating systems leads to a situation where power flushing a heating system is often required. If the corrosion issue is not dealt with in a timely manner it can lead to irretrievable boiler damage or corrosion so bad that the system completely fails and/or starts leaking in many different areas.

This in turn unnecessarily ends up costing homeowners thousands of pounds. As the old saying goes an ounce of prevention is better than a pound of cure.

In short your heating system likely does not need to be power flushed. It is recommended that a heating system is flushed every 5 years, however, if a system is maintained this is a little over the top. In fact only about 1 in 10 properties we visit results in the need to have a complete or partial system power flush. Plumbing and Heating engineers have other tools and workarounds for some heating related issues that can sometimes negate the need for a system power flush.

This is why as above you always need a qualified and licensed heating engineer to look at the entire heating system and its operation to firstly determine the need for a central heating power flush. 

As heating engineers, we look at many factors on your home heating system to determine the need for a power flush. Below is a list of the most common factors a heating engineer will consider:

• Inefficiency and lost heat – As stated above a poorly maintained heating system will collect sludge, deposits, rust and debris to build up in pipes, radiators and the boiler over time. These will slowly result in full blockages and/or restrict the flow of water throughout the heating system.  This can prevent heat from reaching all areas of your home or to specific radiators, resulting in lost heat and wasted money.

• Little or no hot water –  over the last decade’s boilers have dramatically reduced in size. As of today, we are able to install boilers that fit into kitchen cupboards discreetly.  However, the smaller a heat appliance is the narrower the pathways the water has to travel. This results in boilers and in particular plate heat exchanges blocking up faster. Blocked pipework and/or heat exchangers due to an excess build-up of corrosion/magnetite is often the main reason for your boiler and heating system failing to produce little or no hot water.

• Cold spots on radiators – If your radiators are cold at the bottom but hot at the top, your heating system could have a large sludge/magnetite build-up. Cold spots are caused by the build up of iron oxide aka (sludge). Sludge collects at the bottom and in bigger quantities is much heavier than water. In addition, as the sludge is pushed around the heating system pump it becomes magnetised which results in the sludge lining and sticking to radiators. This in turn restricts the flow and return of hot water around the central heating circuit.

• Constant bleeding air from your radiators – As the corrosion process is well underway in your heating system you get the reverse effect of the above issue or your homes heating system can have both. Cold sections will now also be present at the top of radiators. In severely corroded heating systems it is not just air that is produced during the corrosion cycle. In fact, the corrosion process often produces hydrogen sulphite. A qualified heating engineer can demonstrate if this is present to you during an initial inspection to determine how serious your central heating or boiler issue may be.

• Dirty water when bleeding radiators – Bleeding your radiators should be carried out annually as part of your annual boiler and heating system checks. This will help improve heat circulation and convection. However, if the water is discoloured when bleeding your radiators, this is often a sign your heating system needs attention!

• Pump seizure and/or other boiler part failures – Black oxide sludge increases wear and tear on pump shaft and bearings and all moving parts inside a central heating system. We see this time and time again. Sludge and magnetite build-up causes pumps to be far less efficient which constantly cost you vast amounts of more money whilst trying to heat your home.

Over time all heating systems corrode, however, as responsible homeowners it is your responsibility to ensure you have a well-maintained heating system. That way it will cost far less to run and increases the life of your boiler and other components.

OLD WIVES TALES

“I have heard that power flushing will actually cause leaks in a heating system”.

This is unlikely because many power flush systems, such as the ones we use are Clearflow pumps manufactured by Kamco ™. They are designed so that the maximum pressure is two bars or less. It is a high flow rate that makes power flushing effective, not high pressure.

However, do note! On systems that are so badly corroded. Power flushing will remove all if not most of the corrosion. Radiators and other pipework that have become extremely thin due to corrosion could technically start to leak whilst power flushing. It is important to understand in this instance, Heating pipework or radiator(s) would have leaked sooner or later regardless of power flushing if they were too corroded.

“I have heard that the pressure from a power flushing pump will damage my boiler”.

This one is definitely another old wives tale! For safety reasons, the internals (water group) of a boiler has been tested by the manufacturer to withstand 4.5 bar. The maximum pressure of a power flushing pump will never exceed much more than 2 bar at the closet point to the machine, therefore power flushing will not over-pressurise and damage any internals of a boiler.

“You can’t fire a combination boiler to heat up the water during a power flush”.

You should fire the boiler during a power flush if it is working and able to do so. Power flushing chemicals and power flushing work far better when heated than when cold. A combi boiler needs to be at least 0.5 bar water pressure before it will fire, and non-firing is usually related to an apparent lack of pressure.

“You dont need to ever power flush. It is enough to just fit a magnetic filter to the heating system on the return to the boiler”.

Whilst installing a permanent filter is a great idea, it can only remove debris from the water passing through it, invariably leaving debris elsewhere in the system to break loose at a later date. Most permanent filters have a limited capacity and the debris in many systems would overwhelm their capacity. Relying on the standard circulator pump to remove corrosion debris is a triumph of hope over experience as it can never be as effective as the much higher flow rate of a power flushing pump as stated above with Magnacleanse ™.