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By MyPros Staff

As winter approaches, folks start turning on their central heating systems only to find that they aren’t working properly or that some bothersome knocking sound has returned. Corrosion, sludge, pump problems and other malfunctions cause both common and annoying problems.

The information here is necessarily basic advice, so you are reminded to study thoroughly – but never attempt to work on these systems yourself beyond the simple filter replacement and troubleshooting. Leave system repair to professionals, since you are dealing with gas, electricity – and potential danger.

In water-based central heating systems, corrosion begins immediately and such components as pumps and “heat exchangers” suffer from erosion, limescale buildup and corrosion. The efficiency of the system will be adversely affected and the operational cost will increase. Debris, corrosion and their negative effects can raise the cost of fuel by up to 35% over five years.

Look and listen

Do not ignore any amount of banging, booming or bumping noises emanating from the boiler. Also watch for cold spots on radiators and sticking pumps, but if you do notice these it does not mean it’s too late to address. The earlier, the better, of course.

Black oxide, in the form of “sludge,” will build up over time in any unprotected system. It is a natural result of simple corrosion, and results in thick sediment, primarily at what can be termed “points of least disturbance.” This process is at the root of many corrosion-related problems.

“Scale” is the word that is commonly employed to describe the hardened deposits of lime that form on and near the hottest parts of the system.  Confusingly, black oxide sludge can also harden into a scale, although it is chemically different.

Wasted fuel and noise

Corrosion debris builds up in the boiler in an untreated heating system, and in hard water areas the formation of limescale deposits will also be quite common. These deposits have an insulating effect, thereby lowering the amount of heat transferred to the surrounding water.  After just a few months in this operating condition, many boilers will build up enough deposits to result in fuel wastage off from 10% to 35%.

Deposits of scale and sludge in the boiler will cause the sounds that are interpreted as “bumping and banging noises,” often heard throughout the home. Over time, as with other appliances (and your cars), you will become accustomed to the sounds of your normally operating system. Any changes in these sounds should be investigated.

Louder noises such as knocking and thumping can emanate from boilers that are not maintained with the proper water treatment products. The insulating effect of those built-up sludge and scale deposits restricts heat transfer sufficiently for the boiler to possibly overheat, and thus fail. As this is an expensive repair, you should maintain your system to manufacturer specifications as a preventative measure.

Pump problems and radiators

The most common cause of sticking, seizing or failing pump parts is the debris (such as the black oxide and other sludge mentioned above) that gradually “gums up” and wears down pumps and actuator assemblies. Sediment such as magnetite accrues in the lower parts of the radiator unit, and can restrict the water flow. This leads to cold spots on the radiator and reduced efficiency of the entire system.

Internal corrosion is the big enemy of the radiator, particular new ones that must be pre-commissioned before a first use. A process called “pinholing” causes radiator failure when specific deposits of corrosion eat through the metal. Unprotected radiators can fail within just a few years, but a combination of negative conditions in a specific heating system can cause pinholes within mere weeks of installation.

Leaks, etc.

A leaking radiator valve will advertise its presence with discoloration such as green (oxidized copper) on the pipes below it. The aforementioned pinhole leaks in radiators are also caused by “pitting,” a type of corrosion located in natural stress spots such as bends and joints.

It is also possible, though not as likely, for soldered joints to leak, as a result of shrinkage. These leaks are more difficult to locate as the pipes where they occur are not always immediately accessible.

As with any other preventative maintenance, the important thing is to understand and be able to identify the sights and sounds of a properly operating system. Learn as much as you can about these systems, even the ones you will not fix yourself, because your first cost savings will result from reducing the number of false alarms that lead to unnecessary expenses.

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Filed under: Heater Repair


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