Maintenance
www.heatingandventilating.net
Innovation to beat stagnation
Steve Simmonds highlights some recent innovations that make maintenance easier in HVAC systems M
uch like the water in a heating and cooling system, solutions providers to the HVAC industry cannot afford to stand still. As any good facilities manager or engineer knows, stagnation will only lead to problems. Here, Spirotech’s special projects engineer There are many reasons why innovation happens in industry. Changing customer requirements; new materials; global trends; environmental concerns; and emerging legislation. These are drivers of change and progress.
In the field of commercial HVAC the construction of an increasing number of bigger, taller buildings coupled with a push to reduce energy consumption has driven the development of more efficient heating systems, powerful enough to handle the deaeration and pressurisation issues that come with reaching ever skyward. And concern over our impact on the planet and finding ‘green’ solutions has focused minds beyond heating just single buildings towards district heating networks, of which there are over 17,000 in the UK and climbing rapidly. Such concerns were less to the fore when 67 years ago Spirotech founder Frans Roffelsen was inspired to develop his Spirotube, still a core component in today’s Spirotech air and dirt separation products.
An early discovery
Roffelsen had conducted numerous experiments with heat transfer bodies and spirals and the Spirotube’s original function was as a heat exchanger, finding its way into braking systems and X-ray equipment. It was at this time he discovered that air was a disruptive factor during the heat transfer process and from this, the first SpiroVent heating system deaerators were developed.
It is now widely recognised that removing air from system water negates many of the problems that can impact on a system’s performance, and is a vital part of the maintenance regime.
Failure to remove air will lead to corrosion and oxidisation and the creation of dirt, specifically
magnetite, affecting flow dynamics and the system’s efficiency, increasing energy consumption. Tackling these dirt particles has previously been largely focused around dosing with chemicals and using automatic air vents (AAVs) to release free air. However, the next decade is likely to see a move towards system water standards such as VDI 2035 and away from the use of materials that can damage the environment when disposed of, such as chemicals. And, while AAVs are useful during filling or draining, they do little to remove tiny microbubbles, the oxygen from which will react with internal ferrous surfaces, creating magnetite.
Correct environment
Roffelsen’s invention, the ‘heart’ of Spirotech deaerators and dirt separators, creates a laminar ‘no- flow’ zone that achieves the correct environment for microbubbles to rise and be ejected and dirt particles to sink and be expelled, with minimal pressure drop across the unit.
The removal of dirt, an essential maintenance activity, has been made more efficient and easier with the addition of a magnet to the SpiroCross XC-M, a deaerator and dirt separator with optimal hydraulic balancing.
The positioning of the magnet vertically in the middle of the unit, in the direct flow path, maximises its effectiveness, attracting magnetic dirt particles, which can then be drained via a 360° rotating drain valve. The rotating valve makes it simpler for whoever is servicing to position it in the direction of a drain. Another innovation is four mounts for temperature sensors, which can be used with a heating or cooling system that is equipped with an independent control unit The rotating valve is also part of improvements to the dry pocket in the steel SpiroTrap and SpiroCombi units. While the
SpiroTrap is purely a dirt separator, the SpiroCombi is also a deaerator.
Furthermore, the guiding mechanism for the dry pocket pull cord insert (pictured left), used to remove the magnetic dirt, has also been upgraded. This makes it less likely to become damaged and aids maintenance.
Superior solution
A major issue for system designers is ensuring contaminated system water does not find its way into the public network. This is generally addressed using reduced pressure zone (RPZ) valves to provide mechanical backflow protection.
The valve works by ensuring the water entering the downstream system is at a lower pressure than the incoming supply. But this comes at a high cost. Once installed the valves have to be formally commissioned and tested once a year, if not more often, by a fully qualified contractor. In addition, their installation or any alteration of the valves must be notified to the local water supplier and the Water Industry Approved Installation Method (AIM 08-01) must be adhered to.
RPZ valves provide protection up to Fluid Category 4 (CAT 4), which relates to substances that can cause significant harm to health.
The alternative is a simpler break tank, that uses an air gap to prevent backflow and which does not require such a regular, expensive maintenance programme. A CAT 5 break tank, for an even higher level of toxic substances such as radioactive material, was recently introduced to the S400 and S600 series in the SpiroVent Superior vacuum degasser range (pictured left).
The powerful vacuum degassers are specified for heating installations in high rise apartments and offices and extract close to 100% of the air from a system, whereas in-line deaerators are not anywhere near as effective in tall buildings. The S400 and S600s offer a three-in-one solution of vacuum degassing, pressurisation and a Cat 5 break tank.
18 April 2021
www.heatingandventilating.net
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