THE ULTIMATE GUIDE TO FLUE GAS ANALYSERS

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CONTENTS

- Why Use A Flue Gas Analyser?

- FGA uses

- The importance of annual calibration

- Correct use of the analyser

- Do’s & don’ts

- Benefits of bluetooth

- Training

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A flue gas analyser (FGA) is a vital tool for any Gas Safe Register, OFTEC or HETAS qualified engineer when installing, commissioning, fault finding, repairing or servicing heating appliances.

On modern gas appliances you can not see the burner flame. In the past where the burner flame was visible then in theory it was possible to get an indication of the combustion “health” from the flame picture i.e. the colour of the flame and other visual indicators.

Nowadays the burner is enclosed and not visible so we need to determine what’s happening in the combustion process a different way.

Just like the MOT centre putting a probe in the exhaust of a car to sample the gases in order to determine the condition of the engine, we take a sample from the flue, the boilers “exhaust”, to determine the condition of any fuel burning appliance.

An FGA samples the flue gas of a working appliance and measures the critical gases produced in the combustion process to determine if it is operating efficiently, but also if it is operating safely.

Some of the products of combustion are hazardous to humans, namely carbon monoxide (CO) and carbon dioxide (CO2) so by determining the concentration of these gases in the flue (and taking other measurements such as oxygen (O2) concentration and flue temperature, we can learn whether the appliance is operating safely as well as efficiently.

WHY USE A FLUE GAS ANALYSER?

In order to commission, service, fault find and repair a modern gas appliance you need to be a suitably qualified and registered gas engineer.

You’ll also need a Flue Gas Analyser (FGA).

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If the flue gas measurements are in specification for the appliance (as determined in the appliance manufacturer’s instructions) then you can be confident that the appliance is being left in a safe working condition.

If the gas readings are outside of those specified in the manufacturer’s instructions this can alert you to the fact there may be a problem.

There can be many reasons for this but some typical examples would be a problem with the installation or integrity of the flue, an issue with a restricted gas supply to the appliance, a fault on the boiler or perhaps a poorly adjusted air/gas supply valve.

A modern FGA can help you to diagnose and identify the issue, make the necessary adjustments to correct it and then confirm and document that your corrective actions have been effective in getting the appliance back within specification (i.e. it’s operating safely again).

There are functions within modern FGAs that can assist an engineer in determining other issues, like flue integrity tests to check that there’s a good supply of fresh air on the inlet to the boiler and also that the internals of the flue aren’t compromised and letting products of combustion back into the air inlet.

Some FGA’s also have flammable gas leak detectors to help quickly find a leak, useful if you have a failed tightness test. Most analysers can perform let-by and tightness tests too as well as other pressure tests and temperature tests.

In the event of a suspected CO incident or alarm activation they can be used to perform ambient CO testing in accordance with BS:7967 to help a suitably qualified engineer to build a picture of what might have caused the elevated CO situation.

An FGA is a vital piece of equipment for all registered heating engineers, so much so, that most are unable to perform many essential and routine daily tasks without one.

FGA USES

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Due to the essential and safety related nature of the use of FGAs, it is vital that the equipment used is well maintained and has a current and valid certificate of calibration.

Without exception all manufacturers recommend a minimum of an annual calibration and service, but if you suspect your instrument isn’t performing as expected then contact your FGA supplier for assistance.

During it’s annual service and calibration the instrument will have any consumable components checked to ensure they have enough life in them to last to the next calibration due date.

For example, if an O2 or CO sensor is close to the

end of it’s expected operational life then it will be replaced at the time of service.

These sensors used to be charged in addition to the labour element of the service, but now most companies have gone to a system where they are included in the annual service price to help the engineer budget for these essential maintenance costs.

The sensors themselves contain a quantity of chemicals that react with the target gas they’re designed to measure (i.e. O2 or CO). When the target gas passes over the sensor it reacts with the chemicals in the sensor and an electric current is created.

The more gas present the greater the reaction and the greater the electric current. The instrument is calibrated to ensure that the response to gas is accurate across the range of detection. The annual service is vital to ensure your analyser is responding accurately to gas and that any components, i.e. the sensors, are replaced at the correct interval. Not replacing them at the correct time will result in the instrument failing between services and/or giving inaccurate readings. The consequences of using an analyser that is outside of it’s calibration window can be extremely dramatic, potentially allowing appliances to be left in an unsafe condition.

THE IMPORTANCE OF ANNUAL CALIBRATION

The annual service is vital to ensure your analyser is responding accurately to gas and that any components, i.e. the sensors, are replaced at the correct intervals.

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The report your FGA can print is your evidence to show that on the day you were commissioning/servicing/repairing the appliance it was left in a safe condition.

Worst case scenario, if someone is injured as a result of a faulty appliance then the records that are linked to your FGA are proof that when you left the property it was safe.

If the report shows that your FGA was not in calibration (even if the fault has occurred since you left the property) then it doesn’t provide the evidence you need to prove due diligence.

There is no excuse for not annually calibrating the instrument, so for the safety of your customers and your own protection do not use it once it’s calibration has expired.

Anton Analysers

Anton analysers give warnings when the FGA is within 1 month of calibration being due. Once expired the instrument locks out until it’s calibrated to protect engineers from the temptation of using it.

It doesn’t matter if you use it 10 times a year or 10 times a day, it needs it’s annual service and calibration and it’s not worth the risk using an uncalibrated machine.

Due to the essential nature of FGAs and the inconvenience of not having the use of it whilst it’s back with the manufacturer for annual service, the industry has become very focused on turning around instruments and returning them to their owners as quickly as possible.

Anton has introduced a fixed price annual service to give a consistent cost to its customers. The main benefit is that it’s allowed Anton to speed up the process and return instruments to engineers quicker.

Anton identified that the process of quoting for the work that needed doing was taking longer than the service/calibration itself, now that it’s a fixed price they have seen a dramatic reduction in the average turnaround times for servicing.

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Flue gas is very hot and humid as can be seen from the pluming on cold days as the warm flue gas hits the cold air.

This pluming is the water vapour in the flue gas condensing as it hits the cold air forming water droplets. Pulling a hot, humid gas sample into an electronic piece of instrumentation can cause problems as electronics and water don’t mix very well.

For this reason, FGA’s have filtration and water traps (condensate traps) designed in to prevent water entering into the instrument itself.

It is vital that you keep an eye on your FGA condensate trap and ensure you remove any water that collects in it.

It is essential that any condensate/water collected is emptied after every job and not put back into the analyser bag until dried.

If the trap is allowed to fill up or isn’t emptied between jobs then water can be sucked into the instrument which over time can damage the internal components.

The condensate trap in Anton FGAs is in line in the probe assembly so that it’s always visible when using the instrument to ensure you can’t miss when it’s filling up.

The bayonet design allows easy access to completely empty and dry this out. Doing so will really help prolong the instrument’s life and it’s reliability.

CORRECT USE OF THE ANALYSER

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DO’S & DON’TS

There are a number of things you should do (and should not do) to help get the best from your FGA.

1. When taking a sample from the flue ensure that the tip of the probe is in the centre of the flue. This puts the thermocouple in the centre of the flue (the hottest part) giving the most accurate temperature reading and therefore the most accurate efficiency calculation.

It also ensures that the tip of the probe isn’t touching the internal walls of the flue, which are typically very wet with condensate, reducing the amount of water pulled into the condensate trap.

2. Always replace the flue inspection cap after taking your flue gas readings.

3. Carefully observe your condensate trap and empty it of water before it is put away in its bag for the next job.

4. Always connect the flue probe before turning the FGA on to purge the probe and instrument of any residue flue gas.

5. Leave the flue probe connected until the instrument is turned off as this will ensure the probe is purged on shut down.

6. Never remove the probe and put the FGA in the bag whilst the instrument is shutting down/purging as this will result in lint and dirt from the bag being sucked into the instrument potentially damaging the pump.

7. Never leave your FGA in your vehicle at night. It’s an expensive piece of electronic equipment and could be stolen, but also on cold nights condensation can form on the inside of the instrument, blocking sensors from the gas flow and potentially damaging internal components and electronics.

8. If your instrument isn’t performing as expected it could be due to condensation/moisture inside the instrument (either from being left in a cold vehicle or from not emptying the condensation trap).

This could lead to low readings as if the sensors have a film of condensation over them it will prevent the flue gas reacting with the chemicals in the sensors, or it could result in the pump not performing correctly due to water contamination.

Either way it’s always worth warming the instrument to room temperature by perhaps placing it near a warm radiator as this will often resolve any issues.

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9. Most of the time, a fault with an analyser isn’t a fault with the analyser at all, but an issue with the flue probe.

If the flue probe isn’t entirely air tight it will draw in a sample of fresh air from the surrounding room which in turn dilutes the flue gas in the probe.

An easy way to check the integrity of your flue probe is to block the end that normally attaches to the FGA and blow down the flue probe end. If you can blow air through then there’s a leak.

If it’s air tight then you won’t be able to blow down the probe. If there’s a leak check the connections of any in line components such as the condensate trap and also check that it’s correctly assembled.

10. Check your filters regularly for signs of dirt and soot. Replace them if they’re noticeably dirty. Also check that they’re not wet.

This is a sign that you may have drawn water into the instrument but wet filters don’t work as well, so replace with a dry filter if yours is damp or wet.

If they’re clean they can be dried out and used again, but damaged or dirty filters should be replaced.

11. Only perform the start-up and purge when you know you’re in clean fresh air i.e. if the appliance is already running you should not purge the FGA in the same room.

12. Keep your equipment clean and your bag free from lint and dust.

The magnets on the back of most analysers will collect metal swarf which can then scratch and damage the appliance you attach it to.

Giving a wipe down with a cloth periodically will prevent this.

Look after your FGA and it will look after you but the most important rule is only use it in calibration.

Always carry spare filters and paper rolls

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In order for your analyser to interact with the increasing number of applications for smart phones and tablets, it will need to be Bluetooth enabled.

This means sending the report data via Bluetooth from the analyser to a phone or tablet rather than printing the report using the FGA printer.

While most engineers are still using printers to generate their “proof” of the readings they have taken, more and more engineers and businesses are taking advantage of the benefits of Bluetooth reporting.

WHAT ARE THE BENEFITS?

Saved time – sending report data at the touch of a button into a Landlord Gas Safety Report (LGSR) is a lot faster and more efficient than filling out the paperwork by hand, transposing the data by hand into the form and printing the FGA report in duplicate and attaching it to LGSR copies.

Total accuracy – no errors in transposing the data from the screen of the FGA to your LGSR or other report. Incomplete reports or putting the decimal in the wrong place on a ratio are a thing of the past.

Traceability – Every report created electronically can be traced back to the serial number of the FGA that created the data, to the date and time the test was completed and the calibration due date of the instrument.

Some apps will even tag the GPS coordinates of where the device was when the report was created to further prove the validity that the readings were taken at the right place and time with a suitably calibrated instrument.

From an audit perspective, it provides absolute traceability. Electronic systems that automatically record the data and reports against each customer save a huge amount of time from an administration perspective too.

BENEFITS OF BLUETOOTH

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Save money – once you go paperless you don’t need to buy pads, not to mention the time saved by not having to fill in the pads and then send all the duplicate copies to landlords etc.

Create a more professional image to your customers – once a customer receives an electronic gas report they generally don’t want to receive the paper version that they often can’t read and have to file. PDFs of all their reports are easy to read and easy to store.

There are apps out there to suit all business sizes, e.g. the free to download and use Sprint Mobile app from Anton which is ideally suited to sole traders and smaller companies.

Download the app from the Google Play store.

There are also subscription based apps that are a complete solution for larger organisations who want to send jobs to field based engineers as well as receive all the data and reports back electronically, for example Commusoft or Gas-Tag to name just two.

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Combustion Performance Analysis (CPA1) training and assessment, is compulsory for all Gas Safe Registered engineers who carry out work on Central heating boilers and water heaters (CENWAT) or gas fires and space heaters (HTR1). CPA1 has been a part of CCN1 training for some time now.

Gas engineers may be required to undertake combustion performance analysis when carrying out any of the following types of work:

• Commissioning a new installation (where required by the appliance manufacturer)

• Re-commissioning after servicing or after replacement of parts

• When determining service requirements

CPA1 training is based on the requirements of British Standard (BS) 7967:2015. The assessment is designed to test an engineer’s competence to undertake and interpret the results of a combustion performance analysis, obtained across a range of domestic gas appliances including flue-less, open flued and room sealed appliances.

CPA1 training and assessment is included within Logic4training’s CCN1 courses. Contact Logic4training today on 0345 845 7222 or for more information visit www.logic4training.co.uk.

Get your new Flue Gas Analyser from www.Logic4trade.co.uk

TRAINING

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