The modern central heating boiler has made huge advancements over the last 50 years. They are now lighter, more energy efficient and more environmentally friendly than their counterparts from the 1960s, for example. However, just like it’s sixties ancestors, the modern boiler still functions in much the same way and has the same purpose, namely, to heat water and circulate it around a home.
When water is circulated around components made of metal, a naturally occurring chemical reaction takes place which can cause corrosion. This corrosion can cause bits of metal to break off into the system, creating radiator ‘sludge.’ It is this sludge that can cause common problems like radiators not heating up properly or having hot and cold patches.
Another issue can be the build up of limescale, which is a hard calcium carbonate deposit that is especially common in hard water areas. The limescale is very fond of clinging onto the inside of pipes, narrowing the area in which water can flow and reducing the pipe’s thermal efficiency, which basically means your radiators won’t get as hot as they should do.
In addition to corrosion and limescale, over time, general household dirt can make it’s way into the heating system, which also reduces the performance of your boiler and radiators, so the importance of regularly cleaning your central heating system cannot be overstated.
Some of the most common complaints customers have when they call out a heating engineer is that their radiators are taking a long time to heat up, a radiator is warm at the bottom and cold at the top or a radiator is very noisy. All of these are symptoms of a system that needs cleaning.
If the heating engineer decides that the heating system is generally working well, then only a moderate clean may be necessary. In this instance, an engineer would normally isolate the radiators and circulate a cleaner through the rads for around 60 - 90 minutes. A common way of getting the cleaner into the system is to use an aerosol product, which can quickly add the cleaner via a filling loop adapter or straight into the radiator.
When the cleaner has fully circulated around the system, the next step would be draining down all the radiators and adding fresh water into the system. This is usually done via the filling loop or using the feed and expansion tank, normally located in the loft. Once the water runs clear, all radiators should be isolated and purged and a chemical inhibitor introduced to the system. A chemical inhibitor is one of the most important factors in keeping a heating system free from corrosion and should always be added after a system clean.
If a heating system is particularly dirty and has suffered from a lot of corrosion, it is likely that there is a vast amount of sludge sitting in the radiators. A very popular method of removing this sludge among heating engineers, is the use of powerflushing machines due to their effectiveness and the speed with which they can do the job.
Since 2006, the Building Regulations have required that, whenever a new boiler is installed, the system must be fully cleaned and protected and powerflushing is the most effective way of ensuring this happens properly. Such is the importance of cleaning and protecting a heating system thoroughly, many boiler warranties are dependent on the system being flushed, cleaned and protected.
A powerflusher operates at temperatures of up to 85°C and is a very effective way of getting virtually all debris and sludge from the system, particularly when used in conjunction with a cleaner. It is also common for a filter to be attached to the return of a powerflushing machine as the filter stops the dirty water from recirculating around the system. The machine should run for around 10 minutes and the flow reversed and checked very regularly. Clean water should be added to the reservoir tank until the water runs clear.
The next step would be to add a cleaner via the chemical addition port on the powerflusher. This should be allowed to run for at least 60 minutes, again with the flow reversed and the filter checked and cleaned regularly. The cleaner assists the flushing process by lifting the contaminants into suspension, making it much easier to flush out.
The final part of the process is to close all wheel head valves or thermostatic radiator valves except one, to stop the flow to the radiators. With the one radiator that has chosen to be left open, the powerflusher should pump through this rad and out to drain for around 5 minutes. The water level should be maintained by adding fresh water to the tank. The flow should be reversed and this process should be repeated until all the radiators have been flushed. The equipment should then be disconnected and an inhibitor introduced to the system via a radiator, towel rail, filling loop or filter.
Keeping the system clean is incredibly important because it helps all the components to have a longer lifespan, meaning less money spent on repairs, it keeps the system running efficiently, leading to lower heating bills, and most importantly, your system will keep you warm when you most need it to!
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Article by Benjamin Clarke