testo 325m

Steamhead (in transit)

"Anytime an Oil Burner Lights above 100ppm or shuts down above 100ppm there is a mechanical issue that will cause premature sooting of the appliance and/or flame failure".

It's been my understanding that using a pre-purge (a.k.a. valve-on delay) and post-purge (or at least the instantaneous cutoff a solenoid oil valve will provide) goes a long way toward cleaning up these dirty starts and stops. I tried this first on my own burner and it made a big difference, so I've been using this technique a lot with noticeable success. What say ye?

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Karl_5

Testo 325m

I recently bought the testo 325m and was wondering where i can get the acceptable values for what i measure. The mfg doesn't always publish what you are suppose to read. testo does not publish any numbers.

Josh_10

Combustion analysis comes down to one thing.

Lowest O2 before making CO while maintaining the highest CO2 possible. You also have to consider flame stability. sometimes an appliance has to run around 75-100PPM CO in order to be stable. Email me if you would like more info.

Glenn Harrison_2

Here's a few great places for testing information

First, The Bacharach Training Room or you can check the Bacharach training schedule at Bacharach North America

Second, The ESCO institute Buy the book "Carbon Monoxide-A Clear and Present Danger"

Third, contact Tim McElwain of the Gas Appliance Service Training Center at gastc@cox.net . Tim has numerous books on combustion testing. He will be happy to get you what you need.

4. Attend a Combustion and CO class taught by Jim Davis of the National Comfort Institute

Jim Davis

combustion readings

O2 - 6% -9%

CO - less than 100ppm and stable

Flue Temp - Drafthood appliances - 270 degrees to 370 degrees higher than air, water or steam

- Induced Draft appliances - 170 degrees to 270 degrees higher than air, water or steam

- Condensing furnaces - 100 degrees to 140 degrees

- Condensing boilers - greater than return water temperature

Efficiency calculation - Inaccurate and has little value in giving true efficiency.

Oil numbers would be different but can't use Testo on oil because of slow response time to CO at light-off and shut-down.

Maine Ken

Jim, could you expand on the "can't" use the Testo on oil???

Maine Ken

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Maine Ken

Jim, Is this a personel opinion or is it something Testo forgot to mention when selling their units? I have been using my Testo on countless accounts, all oil, is it wrong?

Ken

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Constantin

I believe...

... Jim elaborated on this before, stating that only the Fyrite pro is quick enough to notice tell-tale spikes of CO on light-off that indicate an unhappy burner even if the smoke is zero and all that,

Presumably, Testo has a reason for dampening their output just as Bachrach has one for not doing so.

Jim Davis_3

If I have not actually used something or experienced something I do not comment, guess or have an opinion about it. One of the most critical points of operation I discovered on oil many years ago was that initial sooting of oil burners occur during light-off and shut-down. I have seen burners running under 50ppm of CO and Zero Smoke but light-off and shut-down were well over 100ppm or just one of them and in a few weeks the burner was sooted up. Once I recognized what could cause this to happen and these problems were fixed, I saw oil burners running for up to 2 years without and soot whatsoever. There are still sulfur deposits that might have to be cleaned out but little or no soot. I got my education on 90% condensing oil furnaces back in the 80's. Once corrected these furnaces ran great. Unfortunately they weren't necessarily running at factory specs anymore but they were running better.

Using the Testo analyzer, it would only pick up 25% or less of the actual light-off CO and similar on shut-down. Testo defends this by saying they have NOX filters. Nox is produced in the hottest flame. Light-off and Shut-down are the coolest flames. The main problem is the response time of Testo units is is 4 times slower than TSI and Bacharach. Have done this test at my office with their reps and they have seen the exact same thing. On gas it is not as critical but on oil it is a must.

Josh_10

I have to agree with Jim on this one. The 325 is pretty slow. You really have to look at the big picture.

Jim Bergmann_2

325M and fuel oil (a different perspective)

While gas and oil appliances have no prescribed maximum CO level at light off, high CO levels at light off may be an indication of rough or delayed ignition warranting further investigation. Manufacturers and most in the industry do not consider this a risk to public health due to the very short duration of high concentration then quick drop to safe operating levels in properly operating equipment. As Jim said, CO readings should never rise during operation. They should peak under 400ppm, then drop below the prescribed level allowed in the stack and stabilize within 10 minutes of operation.
NOx is a point to be aware of, many manufacturers of combustion-testing equipment do not filter out the Nitric Oxide (NO) from the combustion gas sample. NO is an acid gas, which is a cross-interferent to all electrochemical CO sensors. A cross-interferent will add “false CO” to the reading proportional to the amount of NO present. (EG. 100 ppm of NO gas will show on an unfiltered CO sensor as an additional 25 to 50 PPM CO.) All Testo stack gas analyzers incorporate replaceable NO filters that remove NOx gas from the CO sample to provide an accurate CO reading. Such filters are not important when measuring ambient CO as NO rapidly converts to NO2 in ambient air. NO2 is not a cross-interferent.
One of the factors influencing NOx formation in a furnace or boiler is the excess air level. High excess air levels (>45%) may result in increased NOx formation because the excess nitrogen and oxygen in the combustion air entering the flame will combine to form thermal NOx. Thermal NOx can be seen at light off and mimic CO giving a false high reading on units without NOx filtration. The oxygen in the combustion chamber is at its highest point before the flame ignites (20.9%) which can result in increased NOx levels at light off. Remember, low excess air firing involves limiting the amount of excess air that is entering the combustion process in order to limit the amount of extra nitrogen and oxygen that enter the flame This is accomplished through burner design and can be optimized through the use of oxygen trim controls on commercial applications. Low excess air firing is used on most appliances and generally results in overall NOx reductions of 5-10%.
High flame temperatures and intimate air/fuel mixing are essential for low CO emissions. Some NOx control technologies used on residential, industrial and commercial burners reduce NOx levels by lowering flame temperatures through modification of air/fuel mixing patterns, or creation of intentional flame impingement. The lower flame temperature and decreased mixing intensity can result in higher CO levels.
The moral of the story is:
Make sure the equipment you are using is specifically designed to measure low levels of CO and incorporates a NO filter. If not, you do not know what you are measuring. The 325M is used all over the world successfully for fuel oil. It doesn't matter how fast you can get a wrong answer!! If the tools you are using aren’t accurate why own them? The worst part is technicians are spending time chasing CO problems that may or may not exist. While Testo is a leader in this technology, other manufacturers are following suit. Some times you just have to respectfully disagree.

Jim Bergman
Testo HVAC/R Technical Specialist

Jim Bergmann_2

Testo published combustion numbers

Karl
Testo does publish number for suggested combustion readings, however we always recommend you consult with the manufacture when setting up their equipment. The recommended set up procedure is available in the Testo Combustion Guide which is available by request.

Jim Bergmann

Mark Hunt

Hi Jim


Let me ask you this.

How long should high CO be at light-off and how could I tell with a Testo?

I love the filters, but how about response time???

Does Testo not believe in fast response? Are they only concerned with "steady state"?? What about shut down? Are we doing a complete combustion analysis, or just a partial analysis?

Accuracy.. Testo is very good.

Response... Testo is lacking.

Mark H





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Mark Hunt

Ah Geeze


Look, Testo like EVERY OTHER MANUFACTURER OF TESTING EQUIPMENT is NOT about to give out combustion numbers. Generic "Rule of thumb" guesses is the best they will do. Testo is no different.

The ONLY way that ANYONE will EVER know what is SUPPOSED to be there is to learn about it! Combustion that is.

Every manufacturer of testing equipment should PUSH their customers to the most intensive training available. Without that, who cares what the damned testers say???

I've used just about every damned tester on the market and I do have a preference. No matter.

What does matter is the ability of the person using the tester to identify dangerous situations. That duty requires "real time" measurements.

Mark H

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Jim Davis_3

My TSI unit is NOX filtered and when testing it with the newest Testo 330 this last fall, they both read exactly 14ppm during the run cycle of the burners. The Bacharach Fyrite Pro was in the 30ppm range or slightly higher. But at Light-Off Bacharach read 600ppm, TSI read 450ppm and the Testo read about 120ppm. NOX had nothing to do with the major discrepancy only response time.

Every book I have read on NOX states that the higher the flame temperature the higher the NOX. The flame temperature is hottest when air is the lowest not when air is the highest. Impinging the flame on a surface quenches the flame and makes it cooler, thus reducing NOX. Having tuned thousands of appliances with an analyzer that measured NOX, everytime the O2 levels were reduced the NOX levels went up. I trained a complete Asphalt company in Michigan several years ago on their asphalt furnaces and found their burners running lean and their NOX below 40ppm, which is the EPA standard. It was costing them a fortune in fuel. Increasing their input and then reducing O2 made the NOX rise to 90-100ppm. After a year they reported that they were saving over $25,000 to $30,000 in fuel at each plant. When EPA calls and says they are schedule for inspection they merely open up their air shutters and reduce their NOX to 40ppm or less to pass inspection. After the inspection they close the air shutter until the NOX is back to 100ppm and they save money again. Obviously O2 & CO readings had to be acceptable Any time flame temperature is reduced, efficiecny is reduced. Every commercial burner that was tuned and the O2 reduced the NOX readings went up, usually between 50-100ppm. Major fuels savings were the end result.

Light-Off and Shut-Down CO readings are not standards, but they are amazing diagnostic tools, especially on oil. If you can't read them you lose this valuable information. If an analyzer is going to be in error on CO, it is much safer on the high side than the low side. When CO is rising the NOX has nothing to do with the reading and rising CO is the most dangerous of all readings.

Anytime an Oil Burner Lights above 100ppm or shuts down above 100ppm there is a mechanical issue that will cause premature sooting of the appliance and/or flame failure. These numbers were established over a 6 years period testing hundreds of oil fired appliances with a unfiltered CO sensors and still hold true to this day. If we cannot attain these CO measurements the only other way to compensate or minimize this problem is to run the equipment lean and less efficient.

One additional point is that even if the ANSI standard states it is okay for appliances to take up to 10 minutes to draft, field testing has shown that if an appliance does not start drafting in the first 1-3 minutes a hazardous condition could occur. If it takes an appliance more than 3 minutes to establish draft and stabilize we have an unsafe and possibly a life threatening condition!!

Testo makes some of the best equipment in the world and do not question their equipment quality. If a contractor works exclusively on gas then I find Testo to be a excellent product with a slower response time.

NOX has little to do about nothing unless you are subject to EPA inspections. This comment is based on 10 plus years of testing commercial and residential appliances with an analyzer that measured NOX.

Jim Bergmann_2

The Rest of the Story

Jim and Mark,
If you had three meters in the stack, and they are all sampling the same flue gas, they would all see the same thing, and should all read the same no matter how fast they make the measurement. A little analogy might help. Lets assume three pick up trucks each pick up an identical load of wood, say a combination of hard and soft wood. . The number of pieces of each type of wood must be delivered and counted for confirmation. The first pick up drives at 70, and the second at 60, and the Testo truck plugs along at 45Mph. The first two trucks arrive much quicker than the Testo truck; the other two drivers jump out and quickly start to unload the wood only to realize they can’t tell the soft wood from the hard wood lumping it all into one pile. It doesn’t matter how fast you make the reading if you have no idea what you have. If all three trucks picked up the same amount and combination of wood (or flue gas) they all should count out the same amount. The moral of the story is being wrong quickly is still being wrong.

Not all NOx is thermal NOx, which is NOx produced by high temperatures and long residence of the flue gas. During combustion, NOx formation occurs by three fundamentally different mechanisms: thermal NOx, fuel NOx, and prompt NOx. NOx is often a product of thermal fixation. “ With residual fuel oil (# 4,5,6 often used for production equipment), the contribution from fuel bound nitrogen can be significant and, in certain cases, predominant. This is because the nitrogen content in residual fuel oil can be as high as 0.3% N2, and conversion to NOx may be 50-60%.” A non-NOx filtered unit would see this as CO. “For natural-gas and light-distillate-oil firing, nearly all NOx emissions result from thermal fixation.” This would mean thermal NOx is not always the culprit in most cases as you are implying.

In the case of the asphalt plant, reducing the O2 is what provided the savings, as I am sure you understand. Lowering the excess air will increase the flame temperature purely by lowering the mass flow through the burner. The thermal NOx increased as a result.

The NOx you will see at light off can be the result of poor burner performance, I am sure you would agree that residual oil (excess) in the combustion chamber would also cause an increase in CO. Add the two together and you would get a highly elevated reading. Residual oil can occur at start-up shut down and during the run period form Prompt NOx. “Prompt NOx is produced by the formation first of intermediate hydrogen cyanide (HCN) via the reaction of nitrogen radicals and hydrocarbons in the fuel, followed by the oxidation of the HCN to NO. The formation of prompt NOx has weak temperature dependence and a short lifetime of several microseconds. It is only significant in very fuel-rich flames, which are inherently low-NOx emitters.” What you are seeing during poor burner performance is a combination of CO and NOx.

If you are looking for an accurate CO reading at light off, run, or shutdown, meters that incorporate a NOx filter as Testo does will do so. It seems you have found a way to diagnose burner problems with a high degree of accuracy with meters that do not filter the NOx allowing you to see the “compounded problems”. As you said, “Testo makes some of the best equipment in the world and do not question their equipment quality.” Testo is measuring the CO, with a very high degree of accuracy. If you are making combustion measurements for compliance, or safety, you need to know the true CO. The measurement is of the up most importance. If you are diagnosing CO problems you need to have an accurate CO reading. If not, what are you diagnosing? Even if you try to use the argument “If an analyzer is going to be in error on CO, it is much safer on the high side than the low side.” Do you not agree you are doing a disservice to you customers when you spend time fixing a CO problem that may not exist. Many times I have seen non-filtered instruments read into what we would both consider to be a dangerous range. (Above 100 ppm in the stack) and the true CO is actually 30-50 ppm below that, well into the safe operating range.

NOx can cause the appearance of rising CO also. As the combustion chamber heats up, the flame temperature increases. Radiant heat from the flame transfers at a slower rate as the temperature difference of the combustion chamber and the flame decrease. As the flame temperature increases, the thermal NOx increases. If the NOx is not filtered, a rising NOx level will appear as rising CO. Again, if you are not measuring the true CO, what are you really measuring?

Mark, to answer the rest of your question Testo meters do perform a complete combustion analysis. They are used all over the world every day with success. If you want to measure the CO and NOx at light off, you will need a Testo 330 with a NOx sensor. The 330 is faster than the 325M, but the 325 is just as accurate for measuring CO. If you want an inaccurate combustion tool to check for poor light off or shutdown use what you have been using. It is probably the best tool for job. You cannot argue with success. However, if you want to perform an accurate combustion analysis, with readings you can count on; use instrumentation that incorporates NOx filtering. Testo is not lacking in response, its just not responding to measurement error.

One the combustion numbers, EVERY manufacture should be about giving combustion numbers!!! Combustion is science. Combustions analyzers are calculators!! It is all about the numbers. Every appliance manufactured has desirable operating characteristics. The science of combustion does not change from appliance to appliance. If you do not know what the readings should be what difference does it make what they are? All types of appliances have a desirable range for the readings to fall, if you don’t know the range the readings are of little value, and if the readings aren’t accurate they are valueless.

P.S. Nice to hear for you again Jim, I always enjoy these conversations. You have brought a lot of awareness of the value of combustion measurement to this industry. Its good dialog.

Thanks

Jim Bergman
HVAC/R Technical Specialist
Jbergmann@testo.com
Sources/Articles Referenced on NOx:
http://www.heatflux.com/Papers/trimmmig NOx.htm
http://meridianaz.co.uk/modules.php?op=modload&name=News&file=article&sid=3

Jim Davis

Jim, I have 3 thermometers in the stack and one responds to temperature in 4 seconds, one 6 seconds and the other 12 seconds. The temperature of the flue changes every 4 seconds. You are saying all three will read the same temperature?? I have a camera with a shutter speed of 45 seconds and one 30 seconds both sitting on tripods. Your truck is moving 10 feet every 30 seconds. Which camera will get a full picture of the truck? Never have seen CO rise ever because of NOX in the field but I am sure it can on paper. As a flame gets hotter fuel burns cleaner and CO always moves in the opposite direction of NOX on a properly adjusted burner. As CO increases to higher levels NOX normally goes down. Residual oil in the combustion chamber is not a normal operating condition for oil burners and has no point in this discussion. An Analyzer that can't read CO at light-off can't read NOX either. Until someone actually experiences the things I am discussing they could never understand the difference between reality and theory. Many manufacturers have been successful in selling combustion analyzers. Unfortunately 99% of those using them could not list the proper operating parameters of a gas furnace other than 3-1/2" gas pressure. Most of them do not know that the CO2 and Efficiency calculations on their analyzers are bogus the majority of the time. The accuracy of the user and interpretation of the readings are always more important than the accuracy of the meter. If I put 100 of the same make analyzer in the flue of an appliance, not one of them would give the same readings. In any given flue you can get an infinite amount of different readings. Any readings that cannot be collected kinda of messes up the interpretation. Light-off and Shut-down readings on oil have been the single biggest diagnostic tool I have ever found in solving mechanical issues on oil appliances. Almost everyone of our students that has bougth a Testo from us and used it on oil has been disappointed and were unable to diagnose their particular oil burner problems. Again it is only on oil that I have said Testo is inadequate in diagnosing all the mechanical issues to those who know the difference.

Jim Bergmann_2

523 and NOx

Combustion meters measure quantities of gasses in the flue gas. Temperature is a measure of heat intensity; it is not measurable quantity (amount). A thimble of boiling water and a cup of boiling water do not contain the same amount of heat, but they are the same temperature. That is why we measure heat quantity in BTUH. Flue gas is also a measurable quantity. The parts per million of CO do not change once the sample is in the probe. If all the meters measure the same sample, they should all read the same. One will just respond faster than the other. What I am getting at is other manufactures of analyzers are measuring a CO/NOx combination. For what you are teaching/proving with oil, a Testo 523 may not work. I agree. However what you are seeing is not what you are measuring. For anyone that does not practice the techniques you are prescribing, a Testo 523 or 330 will work fine. They are used all over the world for testing oil. I also realize that as far as you are concerned, if you are not following your testing protocol you are not performing a complete test. However,the industry as a whole does not practice your testing protocol. Whether the industry is right or wrong the Testo 523 is more accurate than most other meters. Second, if you are using a meter without a NOx filter, the CO readings it is taking are useless for true “CO” testing. The readings will be much higher is some cases than the really are. For instance, if you are in Canada, where they most follow strict guidelines on CO testing, what good is a meter that does not measure proper levels of CO? The second analogy with the camera would be great for a wet kit. Problem is both meters are like a movie camera. Both cameras see the same sample.
As far as the combustion equation and efficiency calculation, each type of fuel has specific measurable heat content. The maximum amount of heat that can be derived from a fuel is based on using pure oxygen as the oxidizer in the chemical reaction and maximizing the fuel gas mixture. In field practice, the oxygen is derived from the air which is 20.9% oxygen, 78% nitrogen and 1% other gasses. Because the oxygen is not separated from the air prior to combustion, there is a negative effect on the chemical reaction. Air is primarily nitrogen. While nitrogen is inert, and plays no role in the combustion process, it cools the chemical reaction (burning temperature) and lowers the maximum heat content deliverable by the fuel. Therefore, it is impossible to achieve combustion efficiencies above 95% for most fuels, including natural gas, when air is used as the oxidizer in the combustion process.
The combustion efficiency or maximum heat content of the fuel is then based upon the quality of the mixture of fuel and air, and the amount of air supplied to the burner in excess of what is required to produce complete combustion. The efficiency calculated by the combustion analyzer is a modified equation that considers combustion efficiency and stack losses. It is a part thermal, part combustion efficiency calculation. The equation is a reasonable estimation of the steady state operating efficiency of the appliance. This is true of all analyzers currently manufactured, and is not proprietary to Testo.
The entire system (furnace/boiler, ducting, and piping) must be evaluated to determine the true efficiency of the system. (I believe this is what NCI is teaching) Combustion efficiency is a valuable part of the system evaluation, but it is only one part of the evaluation process and cannot be used as the sole reason or justification for keeping or replacing existing equipment.
If the excess air is carefully controlled, most furnaces are capable of performing at higher levels than their rated Annualized Fuel Utilization Efficiency or AFUE level, AFUE levels typically range from 80% to 95%

The ultimate thermal efficiency of the appliance is determined by dividing the heat output rate of the appliance by the rate of fuel input. During the combustion process, all furnaces that operate with the same combustion efficiency will produce the same amount of heat with the same fuel input. The combustion efficiency has no bearing on how well the appliance utilizes the heat produced after the combustion process has taken place. Heat exchanger design and its ability to transfer the sensible and possibly the latent heat to the room air determine how well the heat produced by the combustion process is utilized.
Last you said “In any given flue you can get an infinite amount of different readings.” Instead of adjusting the fuel pressure and draft, why not just move the probe around in the stack until you get the reading you need. It might save you some time. I have taken hundreds of combustion measurements a year on live equipment. From manufacture to manufacture, the draft, O2, and stack temperature are very close. The CO is where the difference is. Almost the entire industry is only using two gas units, so the rest is just calculations. If we cannot rely on the accuracy of the combustion readings, what is the point of making the measurement? What difference does it make how accurate the user is or how they interpret the readings if they do not know what they are really measuring? Would you use a calculator that did not add correctly and make the same statements?

I am just adamant about this because there is a fine line between not working for your specific application and not working properly. Testo does work properly for oil. It does exactly what it is designed to do, and it will meet every manufactures requirements for combustion testing oil. I realize that you do not always agree with manufactures, and what you are teaching is of great value, and I agree it is a great tool for mechanical problems. However if you are performing a combustion analysis, and measuring CO for compliance measuring, or you want to depend on your readings for more than just “interpretation” non-NOx filtered combustion analyzers are no good. In my mind it is criminal to knowingly even sell a unit that does not make accurate readings.

Possibly the reason you have never have seen CO rise ever because of NOx in the field is because the meter you were using did not let you see it. The advances in chemical sensor technology have come a long way. Remember, combustion is science. Weather you want to admit it or not on some level you are a combustion scientist. You can only prove the science if you have the right tools to do it. Math works just as well on my fingers, in my head, and on a calculator. What works on paper will also work in reality. I don’t need to see the wind to feel it blow. Sometimes it doesn’t hurt to question our own reality rather than science. It wasn’t to long ago we thought the earth was flat.

Jim Davis_3

Jim we used our meters side by side in class and they were both NOX compensated. We both read 14ppm of CO at 7% O2 during the run cycle. But at light-off your meter read 120ppm of CO and mine read 640ppm of CO.
Most manufacturers do use the same antiquated protocols for testing that were formulated before digital analyzers ever came into being. All reference books are based on what can happen in a Perfect World not the real world. There are still articles being written that say oil doesn't make CO. Last year an industry expert stated that natural gas can't make CO either because there is hardly any carbon in it. To quote an industry standard that says equipment is allowed to spill for the first 10 minutes of operation is ridiculous. The industry does not promote continuous testing to this day and still only require one combustion test after 5 minutes. The industry allows unvented ovens to produce 800ppm (air free) of CO into kitchens. They allow unvented heaters to vent 200ppm(air free)into homes.
The industry uses fictitious combustion calculations to establish AFUE ratings because that is the standard. If everything the industry was teaching was correct there would be no need for Testo, Bacharach or myself to teach classes. Unfortunately to teach false information to avoid offending someone so we can sell more equipment is what I consider criminal. Everytime I read about a CO poisoning it is usually another industry standard that has contributed to the problem. It is an industry standard to allow people to be exposed to excessive CO that can cause permanent damage and even death (UL Alarm standards). There is no industry standard for CO at light-off and shut-down because the industry has never studied it. If it wasn't absolutley important on oil (regardless of NOX)and totally descripted of many mechanical defects, then I would be wasting time teaching this information. Thousands of my students have discovered in the field just what a difference this information can provide and realized they never set a oil burner anywhere close without it.

Dawn M

Let's eliminate all the BS

Ok, guys, I just have to jump in here on this one... I service analyzers, and have seen soooo many things. Trust me, we've seen the good, the bad and ugly of what these analyzer go thru, and what they can/cannot do. So eliminate the NOx factor ~ eliminate the temperature factor... I have video of a brand new Testo 330 and a 2-year old Fyrite Pro 125. In the second part of the video, both are being fed 500 ppm CO (controlled span gas). I'm sorry, but the NOx explanation carries no weight with me because I know what the units were fed. What you don't know CAN kill you. For anyone who cares: http://www.carlscalibration.com/bacharach-vs-testo.wmv ~ I take this very seriously, too, I almost lost my life to CO in 1996.

Dawn M

Let's eliminate all the BS

Ok, guys, I just have to jump in here on this one... I service analyzers, and have seen soooo many things. Trust me, we've seen the good, the bad and ugly of what these analyzer go thru, and what they can/cannot do. So eliminate the NOx factor ~ eliminate the temperature factor... I have video of a brand new Testo 330 and a 2-year old Fyrite Pro 125. In the second part of the video, both are being fed 500 ppm CO (controlled span gas). I'm sorry, but the NOx explanation carries no weight with me because I know what the units were fed. What you don't know CAN kill you. For anyone who cares: CLICK HERE ~ I take this very seriously, too, I almost lost my life to CO in 1996.

Jim Bergmann_2

Properly test (without BS)

Dawn
I am afraid your testing procedure was at fault. There were several things I saw in the video attachment that concerned me. I am assuming since all we could see was the displays that the first test was done in the stack, and the second on a bench. It appears you were trying to prove that if the probes were not in the flue and were exposed to an ambient air and CO mixture the Testo still read low. The problem is you cannot test in ambient air using the same procedure you would use to test in the stack. You should be testing in the CO air free mode, Second, for ambient CO testing the stack probe should not be used, A probe 0832-1247 should be used for Ambient testing. If the stack probe is used in a pinch, there is a very specific procedure to assure a higher accuracy to your result. And finally, if you are to do accurate testing you need to order a test gas mixture of CO and Air or CO and NOx and use a dump tee and a flow meter to assure both meters are seeing the same sample. Neither Jim nor I were arguing the accuracy of the instrumentation, we have both done testing with test gas for accuracy, what we were discussing was NOx at light off. Several manufactures are using NOx filtering in their units. Most only use this filtering in their “higher end” instruments. Testo incorporates this filtering in ALL combustion analyzers because of the importance of accurate measurement.
Since you own a 330, and you want to look at response time open the back and disconnect the hoses on the CO sensor. Remove the sensor, and twist apart the top, The filter under the top cap is the NOx filter. The NOx filter is replaceable. If you TEMPORARILY REMOVE the filter and repeat the testing you will see that is operates with similar if not identical characteristics to the Bachrarch meters you sell. Testo incorporates all of the filtering not only for accurate measurements, but also to avoid sensor damage. The most common problem with inferior instrumentation is sensor damage. After reviewing your website, and looking under the Tech Corner, “The importance of smoke testing furnaces” You can see why filtering is important to protect the instrument sensors. Most technicians do not have access to multiple instruments. It is important that these instruments spend more time in actual use than on your repair bench. Since Testo uses a field replaceable sensor that comes factory calibrated, a service tech can replace the sensor with little or no down time. Everything comes at a cost. It is important to consider things like sensor life, maintenance, battery life, and most of all accuracy when making an investment into combustion equipment. Testo uses the worlds best sensors incorporating proper filtering, the highest ranging sensors for the most accurate readings possible. Also Testo sensors incorporate automatic sensor over-range protection on the 330. To wrap all this up, all Testo instruments come with a calibration certificate. They are guaranteed accurate. Finally monitoring CO at light off is not a health concern it is a diagnostic tool. The short duration of a 1000 ppm light off is much produces 1/10 of the CO a cigarette produces.

Jim Bergmann