ACR News Components of SuccessACR News Components of Success

Components of Success

Specifiers often overlook components such as pipes, ductwork and grilles in HVAC system designs. But doing so can cost them dear, says Jeremy Douglas, Project Director at Brymec.

As pressure mounts on consultants to meet the twin challenges of reducing costs and increasing the energy efficiency of the systems they design and specify, there is an inevitable temptation for them to focus on big-ticket items in a HVAC system that appear to have a greater payoff than the smaller ‘commodity’-type components.

So, for example, when designing large, expensive air movement systems, they might concentrate on the air handling units and fan coil units and dismiss as relatively unimportant components such as pipework, ductwork and grilles.

Although perfectly understandable, this is a mistake because neglecting componentry can adversely affect comfort levels in a building and is potentially expensive both in terms of the system’s running costs and the building’s energy efficiency.

Shrewd building services engineers adopt a system engineering approach to specifying their HVAC systems. A ‘system’ is a collection of different elements that together produce results not obtainable by the elements alone. System engineering involves a systematic effort to translate an operational need into system performance and configuration specifications.

The best way to achieve this is to call upon one company to supply all the components of a ventilation system including pipes, ductwork, valves and grilles. In this way, the specifier benefits from a single source of supply and an integrated system that helps mitigate potential design problems (which could include high room noise levels, poor air distribution and less than satisfactory thermal performance). Service is a crucial element here because these may account for 10% of overall spend, but take 90% time.

With a single point of responsibility, a system can be guaranteed, and risk and worry can be eliminated from that area of the project. But systems engineering also offers another advantage – it enables the designer to find and limit unnecessary costs and avoid over-engineering the system.

If the correct pipes, ductwork and grilles are selected on day one to suit the HVAC system, then it saves a lot of time and wasted energy. It also ensures that the installed system works in-line with the specification it was designed to meet.

Pipework

Life in the HVAC pipes and fittings sector is far from straightforward as the sector has undergone dramatic change over the last five years largely because of raw material price fluctuations. The result is that contractors are far more willing to look for alternative materials such as plastic.

Plastic piping used to be specified ‘from the bottom up’, following recommendations from installers. With this in mind, plastic pipe manufacturers have opted to employ specialist teams to increase the awareness of plastic plumbing and offer security in the shape of guarantees.

However, although there has been a gradual switch to the use of plastic pipe in place of copper, most of the plumbing industry still chooses copper piping and fittings over plastic.

Another trend is the growing use of off-site prefabrication. For most new build projects in London and other large conurbations, road congestion is an issue and there is a shortage of skilled labour. To address this, contractors are moving towards off-site prefabrication which allows transport to take place at off-peak times.

This is a development in pipework that we saw in the industrial market, particularly water treatment, at least 20 years ago in the form of prefabricated pump units, dosing plants and treatment units, where pipework was set up in a prefabricated module and dropped into place on the appropriate plant.

This ‘production, not construction’ approach is gaining in popularity and contractors need to check that they have the right product for the job; failure to do this in the past has resulted in systems failing and some people being wary of using them. Suppliers can provide invaluable information, assistance and training.

There have also been pioneering developments such as the diverse range of Press-Fit fittings we offer. These are faster and simpler to install than traditional methods such as brazing and contribute to safety because no ‘hot works’ are involved. Many of these fittings need to be installed by an appropriately trained installer, qualified to work on air conditioning and refrigeration installations and certified via an approved training course.

Ducting

Ductwork is out of sight and therefore, more often than not, out of mind. However, taking it for granted can also leave the client seriously out of pocket.

The drive for energy savings has resulted in lower pressure drops within many air movement systems. Although generally regarded as a positive trend, this has significant implications for the quality of the ductwork.

A properly sealed ductwork system will save energy because it doesn’t have to overcome leakage losses and the fan does not have to work so hard to deliver the correct amount of air.

Ductwork selection is not always down to the consultant; contractors can also have a big influence on its specification. However, creating a building with a comfortable environment is the responsibility of everybody in the entire supply chain, not least suppliers who have a crucial role in helping with ductwork specification.

Grilles

Given that grilles, louvres and diffusers are often the only visible part of an installed HVAC system, you might expect specifiers to devote considerable care and attention to their selection. Sadly, if you did, you’d be wrong. These high visibility products are too often seen as a low value, commodity items and placed at the bottom of the specification list.

The primary requirement of an air terminal device like a grille is simply to introduce air into a space without causing draughts. But, although they do a straightforward job, they are far more than mere ancillaries.

Suppliers of these products have a great deal to offer in terms of design and operation. Indeed, it is essential that a manufacturer works with both the architect and the M&E consultant at an early stage to ensure the correct balance of visual aesthetics and functionality is achieved.

By being involved at an early stage as part of the project team, we can ensure the correct product is specified visually and with regard to performance and energy efficiency.  Grilles are a critical part of the air distribution system and work best when they are integrated into the air movement design. 

Source: ACR News (October 2017)