PHAM NEWS | JUNE 2025 30 Light CommercialHeating


The burning questions


Burner issues can strike even when everything seems in place. Whether on a small oil unit or large gas system, eff ective troubleshooting – and timely support – can make all the diff erence, explains Riello’s Graham Barker.


E


very burner engineer knows the moment: you’re on site, everything’s wired in, but the


burner just isn’t playing ball. Whether you’re dealing with a smaller residential oil unit or a powerful commercial gas burner, a solid grasp of fault- fi nding is essential – but so is knowing when to pick up the phone and speak to the manufacturer. In both residential and


commercial settings, the most common enquiry is refreshingly simple: “The burner’s not doing anything, what do I check?” Often, it’s an external enable signal holding things up, or a simple wiring or voltage issue. Riello’s control logic is designed with safety and clarity in mind, if something isn’t right, it will hold fi re rather than proceed.


Fan runs, but nothing happens With Riello’s residential oil burners, another recurring theme is the fan motor running while the burner fails to progress. This usually points to a fl ame sensor or component issue. The good news? With some basic checks to resistance values, coil voltages and the sensor, the fault can often be quickly identifi ed. These aren’t complex systems, but they’re smart, and they know when to stop and wait for the engineer to catch up.


Gas valve confusion In the commercial world, one misconception still crops up regularly – that gas valves arrive pre-set. They’re not. On-site commissioning is essential, and Riello provides detailed, step-by-step guidance for setting throughput and regulator adjustments, especially on Dungs MBDLE models. It’s a job that rewards patience, and compensates the engineer with smooth, effi cient operation when done right.


Riello uses


production ‘islands’ according to the lean manufacturing principles, to


improve production effi ciencies and provide additional fl exibility to burner production capacity


Graham Barker Sales & service director at Riello Burners


Emissions expectations Burner performance isn’t just about ignition; it’s about the fi ne balance of combustion. Another common question is: “What emissions should I expect?” For gas burners the typical CO2 level is around 9.5% and very low CO readings, while oil burners push CO2 into the 11.5-12.5% range. With proper tuning, smoke numbers should be minimal for oil burners. These targets refl ect Riello’s


focus on effi cient combustion and emissions control, helping engineers meet performance expectations and compliance requirements with confi dence.


One-second lockout A particularly frustrating fault is the burner locking out one second after ignition. Engineers know it’s about the combustion triangle – fuel, air and spark – but Riello systems off er a level of clarity that helps you track the issue down. On Low NOx RDB BX models, even fl ame luminosity comes into play, with diff user settings used to enhance fl ame detection in blue-fl ame conditions.


Flame on, fl ame off Closely related is the issue of continuous cycling with no lockout, a sign of communication breakdown between the fl ame sensor and the controller. Again, simple checks or adjustments to combustion settings usually solve the problem. In Riello’s Low NOx RDB BX models, fi ne- tuning of the diff user settings can also make all the diff erence as the issue can be that the Low NOx ‘blue’ fl ame is present, but due to reduced luminosity the


fl ame sensor cannot register the ‘running’ fl ame – it will detect the initial ignition which has a high luminosity, but when this quickly settles to the running fl ame the luminosity can be much lower which results in the fl ame sensor not ‘seeing’ the fl ame and attempting a new ignition sequence.


Nozzle size When it comes to oil burners, nozzle sizing is a question that never goes away. It depends on heat input, fuel type and pump pressure, and while the maths is straightforward, Riello’s documentation makes it easier to navigate. The aim is always balanced performance, and predictable control across stages of operation.


Air pressure puzzles On gas burners, lockouts during the purge phase often relate to air pressure switch activation. Whether it’s a fan not starting, a damaged pressure test point, or insuffi cient airfl ow, the root cause is usually mechanical. Riello’s designs make it easy to monitor, diagnose and resolve.


The RS/E and RS/ EV series feature a modular


monobloc design that means


all necessary components can be combined in a single unit


Servomotor switchovers With the phase-out of certain older servomotors, engineers occasionally encounter wiring challenges when fi tting new replacements. These conversions are fully supported with new diagrams and advice, and most issues can be traced back to one or two incorrectly assigned cables.


The blink code Finally, burner diagnostics remain a favourite topic. For


burners using Siemens RMG or RMO controllers, the built-in ‘blink code’ system allows rapid diagnosis of lockout causes. One push of the reset button puts the controller into diagnostic mode, and the LED pulses out the fault code, making it easier than ever to see what’s wrong and get it sorted.


Burner confi dence What these enquiries show, above all, is that even the most capable engineers value backup. Riello’s burners are built for


reliability, but when things don’t go to plan, our technical team is there to guide, advise and support. From residential oil systems to large-scale commercial plantrooms, Riello burners keep the heat on, powered by experience, driven by precision, and backed by a helpline that really delivers. ◼ phamnews.co.uk/625/33


CUT TO THE CHASE


 Many common faults stem from simple issues like wiring errors or missing external enable signals


 A fan running without ignition often points to flame sensor or component faults on oil burners


 Gas valves require precise on-site commissioning – settings are not factory preset


 Low NOx models may fail to detect flame due to reduced luminosity


 Diagnostic tools like blink codes and helpline support help engineers to resolve issues quickly and confidently


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