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Micro Leaks


What is a Micro Leak? 


Have you got Heating or plumbing leaks which are difficult to find or untraceable? Invisible tiny leaks and pressure loss problems which cannot be diagnosed.

Your plumber may have told you, you have a micro leak but what is it, and what does this mean?


The term micro-leak when used by a plumber or heating engineer refers specifically to a leak which is so small it leaves no visible water deposits. The little water which comes from the leak does not deposit any faster than the naturally rate of evaporation so no water is left behind. Therefore there are no water stains or damage, and the leak generally goes unnoticed.

In hard water areas micro leaks leave a lime scale deposit behind. Larger crystals of lime deposits can be observed around pipe joints and valves. In extreme cases just a thin tiny powdery deposits is left, this is extremely difficult to identify. In leaks of more water volume, where there is a greater deposit of water and streaks of lime and magnesium scale can be seen running from the joint or fitting. Often the scale actually ends up sealing the joint though this is a more common occurrence in low pressure and gravity systems.

Problems associated with Micro Leaks.

In sealed systems such as heating systems micro leak result in a slow and constant loss of pressure with no obvious cause. Pressure loss will eventually leak to boilers failing and indicating low system pressure, plumbers can be called out to top up the system at expense. Many systems have to be constantly topped up by heating engineers or the residents themselves sometime maybe once a year or every few months, other cases can be even more frequent especially in smaller systems with a lower total water content one leak makes a greater difference. Constant adding of water to a heating system leads to depletion of chemical rust inhibitors and increased oxidisation of metals as fresh water is added to the system.

Micro leaks are more likely to occur in heating and hot water pipes as the water is hotter so the rate of evaporation is faster.

Loss of pressure through micro leaks will result in closed system such as heating circuits and wet cooling circuits running on low pressure. This will reduce efficiency. Modern domestic boilers will activate a fault code when water pressure is low this protects the heat exchanger. 

Pressure loss in heating circuits can also but the result of pressure relief valves letting by. Have your heating engineer check this.

Leaks can become worse over time due to stress, fatigue, vibrations, building movement, thermal expansion and contraction, and all or any of these plus time.

Plumbing Phrase: Micro Leak

The phrase "micro-leak" is a common term among plumbers and heating engineers The meaning is industry specif and will not be found in the dictionary. Etymology of this use unknown, it was used in a text book popular with apprentices and is something every qualified plumber would be familiar with, though it was in use well before this text book.

Any small loss of liquid or gas from any system could be referred to as a micro leak, but the description above it what is understood by the term when used by plumbers and heating engineers.

Jeff Culkin 

Culkin Plumbing and Heating.

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