Biomass boilers highlight need for flue maintenance

A1 Flue Systems, boilers, biomass, renewable energy
Emphasising the need for maintaining flues — John Hamnett.

Flues and chimneys serving commercial boilers and CHP plants don’t always receive the attention they should. However, the growing use of biomass boilers is putting the issue into a new perspective, as John Hamnett of A1 Flue Systems explains.

Everyone knows that commercial boilers in combined heat and power (CHP) plants require regular servicing and maintenance to ensure they keep delivering optimum levels of performance. But the same applies to flues and chimneys, under the obligations of BS 4076.

The maintenance of boiler systems in the CHP plants of commercial buildings is necessary for two key reasons.

Number one is to ensure that the boiler continues to operate at optimum levels of performance and efficiency.

Number two is to ensure that the longevity and lifecycle of the flue system is maximised.

But there seems to be a disconnect when it comes to the regular maintenance of commercial flues and chimneys.

To the untrained eye, flues and chimneys are simply sections of stainless-steel tubing joined together to carry exhaust gases away from CHP plants, so why should they need maintaining at regular intervals?

Actually, there are two very good reasons why flues require maintenance. The first is from a compliance perspective. The other is a cautionary tale from those who have had to learn the hard way.

The British Standards Institution has long recognised the need to examine steel chimneys at suggested intervals. Appendix A of British Standard 4076:1989 deals with the inspection and maintenance of steel chimneys and says: ‘For lined and insulated chimneys it is advisable to carry out an examination as above at three-yearly intervals subsequent to the first examination. Lined chimneys should also be inspected internally by close examination from a bosun’s chair’ or similar means of support, to ascertain that the lining is still in serviceable condition and fulfilling its task.’ (A.6 Appendix A, page 16 of the British Standard Specification for Steel Chimneys BS 4076:1989.)

But how many people know this and, more importantly, adhere to it? If we can blow A1’s trumpet for one moment, we can genuinely put our hands on our hearts and say that it’s very rare indeed that our flues and chimneys fail. This plays right into the hands of the ‘if it ain’t broke, don’t fix it’ category of building maintenance — but biomass boilers are bringing this issue to the fore.

The popularity of biomass boilers has been fuelled by both their environment credentials and the buckets of cash (in the form of grants and subsidies) that are available to incentivise organisations to switch to the new boilers. Schools and colleges in particular have been big adopters of biomass boilers.

A1 Flue Systems, boilers, biomass, renewable energy
Despite the promise of biomass boilers burning pellets to nothing, the process does actually create infinitesimal fly ash.

However, the bright new dawn of biomass boilers has been clouded with a rise in cases of them breaking down.

And guess what? The finger of blame has been pointed at flues for not being compatible. It’s an industry blame game as old as the hills. But in more than 90% of cases, it’s nothing to do with flues or chimneys.

What the glossy brochures on biomass boilers don’t tell you is that, despite the promise of biomass boilers burning pellets to nothing, the process does actually create infinitesimal fly ash — especially when they are burning cheap or wet pellets. Over time, fly ash, soot and creosote build up and can rapidly reduce the diameter of the flue —leading to the point where the boiler breaks down. It’s also a serious fire hazard.

There is a new school in south London, that keeps hitting the headlines for all the wrong reasons because three or four times a year it has no option but to send all the pupils home and close the school until it can fix its new biomass boiler because it can’t provide heating or hot water.

Just so we’re clear, we didn’t fit the flues. But the school approached our subsidiary company, Commercial Flue Cleaning & Maintenance (CFCM), to see if we’d provide a maintenance contract because the flues need cleaning as regular as clockwork every three months.

In a little over three years, the school has had to spend more than £22 000 on the maintenance and cleaning of a flue and chimney system that it originally spent £16 000 to install. That’s a crazy situation, and one we’re working with the school to rectify by designing and installing a new flue system that will help them significantly reduce their ongoing maintenance costs.

OK, so the school in London is a bit of an extreme example. But, in our experience, this situation is becoming more commonplace, which is why CFCM has hit the ground running in providing a responsive service for those suffering breakdowns and a welcome option for clued-up building maintenance staff and contractors, who can tick the box safe in the knowledge that the part of British Standard 4076:1989 that covers flues and chimneys is covered.

John Hamnett is a director of A1 Flue Systems.

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