Smarter Solutions

Stuart Herritty, Managing Director of WILO takes a look at the issue of pump selection and installation and the latest solutions available.

Over the years, pump manufacturers have developed a much wider range of products for domestic and light commercial heating and hot water applications.

Although intended to give installers and specifiers of pump systems a greater choice in terms of performance and functionality many of these developments have made the issue of pump specification and installation all the more complex.

More recently, a number of new and intelligent pumps have been launched that can potentially help installers simplify the task of specification and fitting.

This new technology will not, however, eliminate some of the basic operating problems that can be caused by a combination of incorrect planning, insufficient time on site or poor system design.

Before looking at the latest circulator technology, it is first worth giving consideration to a few of the main factors that will cause all pumps to operate inefficiently, malfunction or fail.

One of the most useful recommendations that any manufacturer can suggest is to read the installation instructions.

No matter how familiar one is with the equipment, from time to time even the most simple of pumps will be modified and improved, with the latest generation of smart pumps inevitably requiring a degree of new knowledge before they can be fitted; so a few minutes invested at the outset can potentially save considerable time at a later stage.

One of the most basic rules is the correct positioning of the circulator within the installation.

If positioned incorrectly in an open vented installation there is a potential to draw in air, which will subsequently lead to excessive noise or create air locks.

Care should therefore be taken to prevent this happening.

On open vented systems most modern circulators will need a static operating head of around 1.5m to ensure adequate flooding for lubricating the pump's bearings and providing correct venting.

By comparison, a pressurised system, such as a Combi boiler, will normally operate at a pressure that satisfies static head requirements.

A glandless circulator should always be installed with its motor shaft in a horizontal alignment; fitting a circulator with the rotor aligned vertically will prevent it venting correctly, causing unwanted noise, excessive wear and potentially leading to dry running of the top bearing.

In addition, during installation ensure that the electrical connection box is positioned on the uppermost or side elevation of the circulator motor to avoid water entering the electrics.

Similarly, when installing, think ahead in case later work is required on the system; site the pump so that it can easily be accessed and, ideally, isolated by means of appropriate valves to eliminate the need to drain the entire system down to make minor changes.

Glandless circulators use water to lubricate the internal bearings and dissipate heat.

Debris left in the system during installation could potentially find its way into the mechanical components and may cause major damage.

The solution is simply to flush the entire system on completion, before the circulator is installed and operated.

One of the most common causes of excessive energy consumption and system noise is the fact that many pumps are simply over-specified for the duties required.

It is common practice to estimate the maximum system demand, add a percentage to allow for any error and then use a pump with the nearest performance figures, the potential being that the unit could be set to run at maximum, or near maximum output at all times.

In practice, of course, demand from most heating and hot water typically ranges from very low to around 75% of capacity; rarely does demand reach 100% and then only for brief periods.

Over-specification may offer a seemingly easy option for the installer but leads to many pumps running at far higher speeds and for much longer periods than is necessary.

In addition to using considerably more energy than is actually required, in many cases by as much as 50%, this has the effect of reducing pump life and may also have an impact on the function of other system components.

Finally, but by no means least important, the day to day control of a heating system should be considered from the outset, as changing outside temperatures, protracted periods of sunlight and the use of electric appliances within a building will all affect the level of demand placed on the system.

This situation will be further complicated by varying TRV settings in different rooms.

As a result, an unregulated pump will inevitably create a differential pressure that is far higher than may actually be required, leading to considerable waste of energy, uneven system control and potentially extra noise in valves and radiators.

Many of these problems are, however, overcome with the use of the latest pumping technology.

In particular, there are now pumps available that can truly be termed 'intelligent' as they are capable of automatically adjusting their output as dictated by system demand, TRV settings or seasonal conditions.

Perhaps as importantly, pumps such as the Wilo Smart, are available at comparable cost to traditional brand name domestic circulators, enabling both installers and end users to benefit from advances in technology at no extra cost.

These new pumps offer all the benefits of conventional products, in terms of quality, reliability and performance, yet can significantly reduce noise levels and energy consumption, often by more than 25%.

Products such as the Wilo Smart are also easy to specify for both new and replacement applications.

In particular, they are available in one standard size that can be used in most domestic and light commercial heating systems, so there is generally no need to size a specific pump for each building.

Similarly, installation is quick and simple.

Ports are a standard 130mm size, while flats on the inlet and outlet ports allow the pump to be held firm with a spanner while the unions are tightened.

Quick snap electrical connectors make wiring of live, neutral and earth connections easy, with set-up being via a switch on the terminal box, allowing selection of the most appropriate setting; once a simple pre-programmable setting has been made the pump will automatically adjust to suit system performance.

New technology will make the way circulating pumps are specified, installed and used much simpler and more effective, bring savings in time and cost to installers and reducing energy consumption for end users.

It should not be forgotten, however, that no matter how sophisticated the pump its performance and reliability will always be dependent on the skill and experience of the installer.

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