Black Sludge build up in your heating system can cause all sorts of problems. It usually starts with a cold patch in one or two radiators. Over time the radiators will stop working all together, the problem will spread to other radiators and your boiler, the sludge will also start to jam up your circulating pump. Eventually the entire system will fail.
The primary cause of this problem is air getting into the system!
Air+Water+Iron = Rust aka Black Sludge
Before power flushing, have your system checked for design faults that may allow air into the radiators. The most common of these is pitching. With poor pump placement or bad system design heating water can get "pitched" from the expansion pipe into the attic tank collecting air as it does so. This air even though it may seem like a tiny amount will quickly begin to make rust out of your radiators.
Other problems include negative pump pressure through the rad valves and small leaks. A leaking cylinder coil will cause the system to sludge up very quickly.
Power Flushing will remove the sludge and leave the system clean and working normally again. To prevent further problems it is best to add corrosion inhibitor to the system afterwards.
Leak sealer may also be added if a small leak caused the problem.
This is a thermal image of a radiator that has a substantial sludge build up. The blue area in the centre is a large cold spot that is caused when the sludge blocks the flow of water through the radiator. As you can see only about 40% of this radiator is actually heating.
The signs of a build up of iron oxide in a system are:
Parts of a radiator not heating
Some radiators not heating at all
Frequent need to vent radiators
Black water/sludge when venting the radiators
This thermal image shows a partial blockage in a radiator again due to sludge build up.
To Power Flush your heating system we attach a special flushing pump which operates at a high flow rate but does not build pressure. Chemicals are added to the system which will help loosen the iron oxide build up. The water is circulated at a high velocity through the system and the broken down sludge gets carried along with it. This sludge filled water is then dumped and replaced with clean water. To prevent the iron oxide build up from
re-occurring a chemical inhibitor is added, leaving your system clean, efficient and protected from future damage. For an average size house the whole process can be done in a day with the minimum of disruption. We generally try to set up the pumping equipment outside the house for cleanliness. We do need access to every room and the attic. Power Flushing can be aggressive and, although unlikely, may uncover leaks that would have been sealed with rust.
This image shows a radiator that has been powerflushed. The sludge has been removed and water is flowing freely throughout the radiator creating an even heat distribution. This in turn maximises the heating systems efficiency, with a reduced heating up time thus lowering your oil/gas bill. Removal of sludge also reduces the risk of pump and boiler failure.
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