Heat of the moment

Published:  06 August, 2012

Trend Controls, boiler, space heating, controls, BMS, BEMS
Keeping the BEMS up to date — Matt Peasnall

With annual boiler checks now scheduled by many organisations, Matt Peasnall of Trend Controls answers readers’ questions about checking and reconfiguring a building energy management system (BEMS) as part of a boiler maintenance programme.

When is the best time of year to carry out boiler testing and maintenance?

While basking in summer sunshine a building’s heating system is usually the last thing on a building manager’s mind. However, August is in fact the best time to carry out essential boiler maintenance in preparation for the winter months.

Not only does this make sense from a planning point of view, it also means that any boiler downtime will have minimal impact. Carrying out this type of work in the winter months could cause significant disruption, so it really is advisable not to leave it too late.

Can boiler maintenance have an impact on the operation of a building energy management system (BEMS)?

Yes it can. A BEMS will usually be optimised in line with a certain level of plant performance, so increasing a boiler’s efficiency will require setpoints to be adjusted.

To make sure that a BEMS is configured to provide the best comfort conditions and the most efficient operation, it is advisable for the boiler engineer and the controls engineer to be on site at the same time. However, this is not always possible, in which case a controls engineer should make a visit soon after any remedial work to a boiler is completed.

If a boiler does not require any remedial work, does this mean that a BEMS’s setpoints will also not need to be adjusted?

Regardless of any work that is, or isn’t, carried out on a boiler, August is still a good time to optimise a BEMS.

The key reason for this is that during spring, when the weather starts to get warmer, building occupants tend to adjust the setpoints to account for the milder temperatures. For example, in April and May, temperatures can be down to single figures in the morning, but rise quickly throughout the day. This can mean that buildings become very warm in the afternoon, leading to occupants becoming uncomfortable and unproductive.

Regular maintenance keeps boilers in peak operating conditioning, but do changes to the systems they serve require the BEMS to be updated?

It is also important to assess the condition of the BEMS’s sensors — particularly those used for measuring outside temperature. If the sensors are not working to their full capability, this will affect the compensation setpoints, so before the winter months kick in they need to be checked and, if necessary, recalibrated and reset.

This important exercise ensures that the sensors are fully optimised. Sensors use algorithms to learn the response rate of a building, which then minimises the start-up period of its boiler depending on the prevailing outside conditions. This means that the required temperatures are achieved at the start and end of the occupancy period and, in turn, significant energy and cost savings can be realised.

What other factors can affect how well a BEMS operates?

A wide range of issues that can prevent a BEMS from being as effective as it should be. Put simply, it is not ‘fit-and-forget’ technology and can only work to its full potential if has been correctly maintained.

When a BEMS is first commissioned, it is configured around an existing building layout and occupancy patterns. These can change over time. New layouts, repartitioning, and the addition or moving of equipment can lead to some areas being too warm or too cold — all of which has a massive effect on the way a BEMS operates. It is also important to remember that these activities can lead to accidental damage to the sensors, something that could go unnoticed if they are not regularly checked.

Again, schools have a tendency to undertake moves and changes during the summer holidays, so a building layout used in the spring could be replaced by something quite different when the academic year starts again in September. Therefore, not adjusting setpoints to compensate for these changes could easily lead to a BEMS not doing its job properly.

How can boiler and BEMS maintenance impact on a building’s overall energy use?

Nowadays, all building owners, facilities managers and occupants require greater visibility and transparency of their energy consumption, and need access to relevant energy data.

By applying a range of control and monitoring initiatives, boilers and other building services can operate in strict accordance with demand, thereby avoiding unnecessary use of energy. The data produced by the BEMS enables better analysis, understanding and improvement of a site's energy usage and costs, particularly if the information is presented in an organised and informative way.

The good news is that a regular boiler maintenance programme which includes sensor checks and recalibration is a fairly simple process that will make a BEMS truly fit for purpose, thereby delivering immediate savings.



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