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Get your hands dirty

Arguing that theoretical knowledge cannot compare with practical experience, which helps deal with unexpected challenges, Jean-Christophe Carette stresses the importance of practical training for hydronic distribution.

| | Aug 18, 2013 | 11:27 am
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Arguing that theoretical knowledge cannot compare with practical experience, which helps deal with unexpected challenges, Jean-Christophe Carette stresses the importance of practical training for hydronic distribution.

“In theory, there is no difference between theory and practice, in practice there is.” This statement by J van de Snepscheut is certainly applicable to hydronic systems, where on-site commissioning often brings surprises as clogged strainers, pipes damaged or not connected as expected, shut-off valves that are partially shut, check valves installed back-to-front, etc.

Finding these issues in time amongst a deeply ramified network of thousands of pipe segments is hopeless without measuring capabilities. This is why we strongly believe that the presence of test-points on balancing devices, combined with the use of modern balancing and measuring instruments, is a key element to commission a system for energy-efficient operation. After all, in the 21st century, it is not unreasonable to consider that the time of touching pipes with the hand to feel if there is a flow is gone. Lord Kelvin was already expressing this view in 1883: “When you can measure what you are speaking about and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind.”

We have seen a general trend these last years towards the integration of multiple functions into one valve body. I think especially about the control and balancing functions with the nowadays widely spreading pressure-independent balancing and control valves. If this type of valve has a real use in a number of cases, it has been, unfortunately, applied largely blindly, disregarding the hydronic structure particularities that each plant has. While this is usually presented as an effective “fit and forget” approach, it often ends up in a “fit and regret” result, as the very useful self-acting differential pressure control part of this type of valve actually hides the reality of the circuit in which it is installed if it is not properly measured and commissioned. This is how a technology that can deliver very interesting energy savings actually leads to running a plant with higher energy consumption than expected.

Obtaining an energy-efficient hydronic distribution actually requires the implementation of a systematic methodology that starts by the analysis of the schematic drawing of the piping and the extraction of its skeleton. The backbone of this skeleton is then determined, and the entire pipe network is decomposed into hydronic modules that can be treated one by one with testing and adjusting methods that are designed to obtain the lowest possible pump head for circulating required flows in each terminal unit. Implementing this methodology step-by-step is something that everybody should experience at least once. It is an enlightening experience which reveals how simple it can be to obtain pumping energy savings by up to 40%.

We see, indeed, too often the screens of Variable Frequency Drives displaying permanently a sad 50 Hz (or 60 Hz depending on the countries). It is the last straw considering that the choice of investing into variable speed pumping is all about obtaining a reduction of the pumping energy consumption.

Methodologies can certainly be taught through well-prepared presentations. The whole question is whether they are then really understood and further remembered. In this respect, there is nothing that beats practical experience whereby people get faced with unexpected difficulties, which they have to circumvent. This approach was already recognised as most effective by Confucius who left us the following statement: “I hear and I forget. I see and I remember. I do and I understand.”

These are the reasons why we find critical to propose practical trainings in training centres equipped with realistic models of hydronic circuits incorporating variable speed pumps and valves of different types. I can only encourage people interested in seeing and learning to visit these training centres in order to get practice in a safe environment before applying procedures on-site.

The writer is Hydronic College Director, TA Hydronics. He can be contacted at jc.carette@tahcollege.com


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