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A solid foundation for heating efficiency

Martin Wilkinson explains why correct pressurisation is vital to heating system efficiency.

The issue of dirt in heating and cooling systems, and specifically metallic dirt – sludge or magnetite – has for long been seen as the prime culprit of system breakdown.

This focus on dirt removal, and not water quality, has served to create an inaccurate picture of exactly what causes systems to malfunction or breakdown and, as a result, has led to incorrect methods of installation and excessive maintenance to persist.

The industry has also been guilty of being reactive in its approach to system problems, only taking action when symptoms have become so severe that they either malfunction or grind to a halt all together. The reliance on chemicals alone to fix the problem is also widespread in the UK, and it’s a practice that continues to deliver poor long-term results.

What isn’t being discussed fully enough, but is in reality the most critical factor in achieving system efficiency, is the role that pressurisation has to play and how the changes in system pressure can dramatically affect the efficiency of a building’s heating and cooling system. To not consider pressurisation, or to ignore it completely in the design phase, will almost certainly lead to system breakdown.

There are a number of key factors that installers, specifiers and designers need to consider when installing a new heating and cooling system or when adding to an existing network. Laying solid foundations is key, and correct pressurisation is a vital component.

Avoiding negative pressure, treating system fluid as an essential component and allowing for optimum heat transfer are vital considerations to achieving a healthy system. Of upmost importance, though, is to treat the building as a whole; installing a heating and cooling system that meet its needs. If a building has been extended, for example, then the heating requirements will change as a result, so the products installed to deliver the increased capacity need to change too.

The first step to achieving a healthy heating and cooling system should always be to get the pressure right. The design and installation of the right pressurisation system is paramount; it ensures the system is fit for purpose and can effectively transfer hot or cold water to the desired location.

Avoid negative pressure

A poorly designed, installed or maintained pressurisation system can lead to negative pressures around the circuit. Air can be drawn in through automatic air vents, gaskets and micro leaks. High-pressure can lead to water being emitted through the safety valves and then the subsequent frequent addition of further raw refill water.

Fluid – system component

Re-filling should be avoided wherever possible but adding new make up water to a system is a necessary evil. The introduction of fresh oxygen-rich water depletes any level of corrosion inhibitors that may be present and the onset of corrosion is then inevitable. If scaling is allowed to accumulate it will reduce the heat transfer capacity and require the pump to work harder to function; pressure will drop as a result.

Optimum heat transfer

Ensuring that heat is transferred to the right place at the right time is crucial to a properly functioning system. When heat is unable to travel to the desired locations, it is most likely due to a blockage in the system, caused by air, corrosion or limescale build-up. Such restrictions can seriously hinder the heat transfer capabilities and will mean either the pump or the boiler needs to work harder and is thus not running at optimum efficiency levels, which causes energy loss.

Always factor in pressurisation

When buildings are extended there’s often little thought given to the need to increase vessel size to accommodate a bigger heating and cooling system, which will likely result in a reduction in pressure and reduced heat exchange capacity.

Latter extensions to existing heating and cooling systems can be left open to malfunction if the initial design and installation requirements have not been considered. It is also common for a design recommendation to be made at the planning stage but not carried out in the final installation, usually as a result of cost cutting measures. This scenario is particularly common in large municipal installations like hospitals, which also suffer from many of the problems associated with open spill systems, which are commonplace in the UK market.

In an age where energy efficiency reigns supreme, allowing heating and cooling systems to continue to work inefficiently is a situation that needs to change. End users and installers shouldn’t be expected to operate under the assumption that systems will always malfunction and slow over time, especially as it’s a circumstance that is entirely avoidable.

A reliance on chemicals to cure system problems is not working, nor is focusing solely on removing dirt and not considering pressurisation in the mix; the results of which are eventual system failure, unnecessary costs and poor heat exchange. These are all symptoms that can be easily remedied by laying the right foundations and taking the correct steps to ensure air, dirt and water are treated in the right way.

Spirotech’s pressurisation range includes the SpiroPress Fill, SpiroPress Control and SpiroPress MultiControl.

// The author is the commercial manager at Spirotech //

1 July 2014

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