Joined on August 25, 2004
Last Post on May 15, 2013
@ January 31, 2013 9:05 AM in passive air intake for oil burner vs direct ventIt should be known that cold air is the worst combustion air for combustion. Many industrial plants pre-heat their combustion air and can run at O2 less than 2%.
Cold air is denser but the molecules are so close together there is very little surface area to mix with the fuel and it actually takes more air when cold. I don't like the cold air chilling the oil in the drawer assembly either. Cold oil doesn't burn very well.
Trapping passive combustion air can minimize excess infiltration when not needed.
@ January 31, 2013 8:54 AM in Combustion analyzer readingI was just in Denver a couple of weeks before Christmas. We probably won't be back there until fall. ONly class out west will be in Cypress, CA in February. We do have classes in Phoenix and sometimes Las Vegas. Because of feedback from thousands of my students in the field, we keep fairly current with new equipment and problems along with the same ones that have existed forever. The training is 10X better today than it was just a few years ago.
@ January 30, 2013 8:40 AM in Combustion analyzer readingNatural Gas, LP and Oil all make about the same amount of NOX in our combustion processes. If you use it on one you would use it on all.
NOX does not significantly interfere with our combustion readings to cause any problems. It affects the CO reading and makes it slightly higher, However, I have seen many times in the field that the analyzer with the NOX filter had higher CO readings than the one without. I am talking about analyzers that are recently calibrated.
All CO sensors in different analyzers have different sensitivities. It is almost impossible to get the same CO reading in a flue from two different analyzers, even the same make.
But lets look at what kind of difference a NOX filter versus a non-NOX fliter might make on a standand cast iron boiler.
NOX filter analyzer readings: O2 - 6%
CO - 10ppm
Flue T - 470 degrees
Non-NOX filter readings O2 - 6%
CO - 25ppm
Flue T - 470 degrees
Most combustion trainers use 100ppm "As Measured" as the maximum CO in flue gas of vented appliances even though the ANSI standard is 400ppm "Air Free". 100ppm "As Measured" is 140ppm "Air Free" @ 6% O2 so it is well below industry standards. The reason I use "As Measured" is because you must have an O2 reading to get "Air Free" and sometimes our O2 sensor might not be working or someone is using just a CO analyzer.
Therefore the only time that the NOX filter might make some difference is when the CO reading is near 100ppm or 400ppm, which ever someone likes to reference. Red Tagging is at 400ppm "Air Free" according to industry standards ANSI Z21. The analyzer without the NOX filter will Red Tag equipment at a little lower ppm than one with one. Equipment shouldn't be running anywhere near 400ppm CO anyway!
Saying a meter with a NOX filter is more accurate is not necessarily true. It depends on the calibration of the meter, the sensitivity of the sensor and the protocols of the person using it. It have seen many NOX filtered analyzers read higher CO than ones without. If the filter isn't built in I see no reason to spend additional money to add one.
@ January 29, 2013 2:23 PM in Loud Smith gas boiler with Powerflame burnerI have never known Power Flame burners to be that noisy but a cast iron boiler should absorb most of the noise. It is possible the burner needs better adjusting. See if the people that service it have any combustion readings that you can give us.
@ January 29, 2013 2:19 PM in Combustion analyzer readingCO* is CO "Air Free" or no Oxygen in the sample. This is a theoretical calculation that indicates that if there was no Oxygen(also called Excess Air) in your flue sample, this is how much CO the burner is actually making. Based on your readings your O2 reading is around 3% which would not be too much excess air.
NOX is a by-product of good combustion and hot flames. NOX interferes with all CO sensors and causes them to read 10-30ppm higher than the actual CO being produced. We have have CO monitors go off in dentist offices because their N20 tanks(laughing gas) were leaking.
The only difference between an analyzer with a NOX filter and one without one is that the one without one might end up a little safer because you think the CO is higher than it actually might be. In the field over the last 25+ years this has made no difference in the setup or tuning of equipment.
I only use the "Air Free" CO to show the customer and maybe get them to react to our recommendations a little sooner.
@ January 14, 2013 2:45 PM in Cycles per hourLess cycles per hour doesn't save any money if you are trying to maintain the same temperature. Sure will make you colder.
Today, the mentality is consumers really don't want the temperature in their house to be what they set their thermostat for. So we have controls and equipment that avoids satisfying the setting.
@ January 14, 2013 2:36 PM in venting to longAccording to their specs PolyPro is only rated for 230 degrees and the Burnham rv6 flue gas temperature is above that.
I am surprised that 29-4C stainless is corroding so bad. If it is corroding I would think the inducer would definitely be on its way out. I would be more concerned if the boiler was venting 100% of the flue gasses.
Needs a combustion test. Just because it runs, doesn't mean its venting. No one has died yet, but that may just be dumb luck.
@ January 10, 2013 10:34 AM in Cause of CO poisoning unknownIt just keeps happening and know one seems to care. People getting poisoned and no one can find the problem. Wow, if you can't find the problem after someone is poisoned it is pretty doubtful you will ever prevent it from happening. The latest is from Minnesota which has the least CO trained contractors on my list. The good news is everyone is dying warm!
@ January 10, 2013 10:29 AM in Gas Boiler and Water Heater Flue / VentingI see you have posted this on another HVAC website also and I am not sure which one you will read first, assuming your not in the hospital yet. But that extra hole is a horizontal drafthood that is most likely illegal. It is singly one of the most dangerous drafthoods ever made. 100% of the ones I have tested were causing occupants to get poisoned. Get someone quick that knows what they are doing to fix it quick.
@ January 10, 2013 9:03 AM in Gas Boiler and Water Heater Flue / VentingThat opening in the water heater flue is an old and dangerous horizontal drafthood. You are lucky you are not in the hospital because they prevent appliance from venting better than any device I know. Needs to be removed immediately!!
@ January 10, 2013 8:22 AM in Testo NOx filteringFor many years I used a combustion analzyer that measured NOX. NOX is a by-product of efficient combustion. The hotter the flame the more NOX you make. Testing many commercial and industrial appliance, gas and oil, I never saw a NOX reading above 120ppm. This is with O2 readings around 2%-3%. However, as the O2 increases and the flame gets cooler the NOX goes down to 20-ppm to 60-ppm. This should cause about a maximum of 10-ppm to 30-ppm higher CO reading. With 100ppm being the maximum we teach in flue gas samples for all vented appliances, if you were readings 100ppm of CO with an analzyer that did not have a NOX filter, the CO might only be 70ppm. Not really going to mess anything up. You will end up just slightly safer.
The problem I have seen over the years is when I put 2 analyzers in the flue that have NOX filters and they don't match either. Many times I have seen an analzyer read higher CO with a NOX filter than without one. These readings were taken with units that were just checked for calibration.
I still question whether or not the NOX filter de-sensitizes the CO sensor from CO. Something to also consider is that all CO sensors have different sensitivities in flue gas. It is almost impossible to get two different analzyers to read the same CO when testing.
Whatever analyzer you have should be accurate, dependable and repeatable to itself, not any other analzyer. O2 & temperature are the only readings that will ever be close from one to the other. Trust whatever analyzer you have and don't worry what somebody else's might be reading. As long as it responds to CO it is good to go.
@ December 11, 2012 12:15 PM in Cast Iron vs High EffficiencyIf you want a piece of equipment that is antiquated and the same efficiency as your old boiler go with Cast Iron.
If you are interested in saving energy and actually get some return on your investment you will go with High Efficiency. At least a 30% difference in real efficiency.
@ December 11, 2012 12:11 PM in Another school scare.I like the fire departments comment on the 5ppm they measured. "It is the same amount you would find in the hallways if someone was smoking." This must be a pretty liberal parochial school. Of cousrse the school was aired out before they got there and I guess everyone stopped smoking.
@ December 9, 2012 11:02 PM in fluctuating draft with power vent + power gasMost power venters should have a damper control to adjust the venter because of all the different lengths of flues. The draft between the venter and the barometric should be no more than -.06"W.C. You can make a slide plate damper or neutral pressure adapter to adjust this but the venter should have its own damper.
@ December 9, 2012 10:56 PM in Schools poisoningsThat is probably what the kids parents would be charged with if they carried a personal CO monitor to school. I recommend my students get one for their kids to carry in their school bags.
I will be following up on this story this week with some of my students from Atlanta. I even emailed a writer for a newspaper in Atlanta I had talked with on the phone and ask him if he wanted to get the facts straight. Seems like he is satisfied with what the gas company, fire department and doctors are saying.
@ December 9, 2012 12:35 AM in Schools poisoningsOne of the first places I tell my students in Carbon Monoxide class to check is the school their kids attend. In my 34 years of testing, schools still rank as Number 3 on my most dangerous building list.
Atlanta school administrators had their maintenance people tear down the boiler before the state inspectors could check it for the problem. The boiler had been serviced two days before the incident.
NO SERIOUS INJURIES!!! 6 children were carried out unconscious!! Stupid reporting or just a cover up??
News from Albuquerque, NM shows a technician testing all their equipment. But in the video he is testing in the wrong location on one piece of equipment and doesn't have a clue what the readings mean.
One doctor reported that CO starts to hurt you at 50ppm. Yeah if you work in an industrial plant which is the OSHA standard. Of course all the alarms that might be installed won't go off until they hit 70ppm for at least an hour. They would be much safer in a parking garage.
Too often I read stories about poisonings within days after equipment was serviced. Makes one wonder if they would all be better off if no one touched it or what does a "Qualified Contractor" really mean. Apparently if you have a combustion analzyer, have a HVAC license and are EPA Certified you must be good!
The CO stories in the news all over the country after this school poisoning are just as horrible as they were 30 years ago. In is a shame that in the year 2012 the ignorance about CO hasn't changed.
@ December 4, 2012 8:23 PM in Draft on cold boilerYou look at the draft reading after several minutes. If it is -.02" or higher you do not have a negative pressure problem, but if it is lower you do.
If the draft is -.02" or higher and the CO is rising that is an equipment venting problem.
@ December 4, 2012 7:49 AM in Draft on cold boilerAn unsafe negative pressure would be one that doesn't allow the boiler to start venting within a few minutes. To determine if an appliance is venting with a combustion analyzer(which is the only way it can be verified) is to watch the O2 and CO readings. If they are stable after 3 minutes (could still be going down slightly, but never up) you are venting. If they start to rise after they bottomed out you have a venting problem.
@ December 2, 2012 11:51 PM in Power vent condensation problemsStill have flue gasses in the chamber after 2:30 minutes. Increase post-purge to 8 minutes and you will be fine. This is based on actual field situations that I was involved in and ask to solve the problem. I wish I knew why oil takes that long to purge all the moisture but it does. It also helps prevent delayed after drip.
@ December 2, 2012 11:37 PM in Weil McLain UO-3 HelpDid you do a CO test. I have seen many oil appliances have zero smoke but have CO in the thousands of ppm. It is critical on oil to get a CO spike reading when they light, watch the CO the whole run cycle and then watch the spike at the end. Back in 1984 I learned that a smokeless oil burner isn't necessarily running clean or safe.
Two things that would definitely contribute would be running at pump pressures below 125# and/or running a 2-line system.
@ December 2, 2012 11:31 PM in Draft on cold boilerIf you mechanical room is positive you will have a slight draft in the chimney, even with a cold boiler, but this is not the norm. Most mechanical rooms are negative unless some type of mechanical fan is running during the off cycle. The important question is what is it during the on cycle. Without some type of mechancal combustion air fan the room is still going to be slightly negative. The question becomes is whether or not the flue can overcome it.
@ November 25, 2012 9:35 PM in draftHow high up in the flue did you take your draft reading? Could you be too close to the inducer?