Combustion Analysis

GroundUp

This may be a silly question, but please bear with me. I've been in the trade for 13 years and have installed my fair share of gas boilers, but primarily commercial where we have a service tech always do the startup and combustion analysis. I always try to learn something but usually gain nothing, but it seems 99% of the time the combustion numbers are in line and need no adjustment. There have been quite a few where I started them up to make heat quick and were gone over later, with no ill effects. I don't own an analyzer nor do I know how to use one, so I've always hired the analysis out when doing residential but am looking to maybe start doing it myself. Local heating company has been doing this for 50 years and was completely dumbfounded when I mentioned an analysis, had no idea what I was talking about. This got me wondering; how necessary is it, really, on new startup? How often do you fellas need to make adjustments on a new unit? The piping side of things is what I know, but I'd like to gain some knowledge from the service side of things. Anyone care to share? Some insight would be great. TIA!

lchmb

I test each and every new install I do..if you dont test you dont know..and it's the one you fail to test which will do the most damage. I like the Testo and have the 320. We are outfitting all the tech's in the shop with the 330 and requiring everything be documented.. CYI and happy heating..

EBEBRATT-Ed

Really need to test. Others will disagree with me but although you can't smell Co oil will usually smell from something else in it or make soot when not burning right.

Gas not so much. You really need to test. A bad chimney which may have nothing to do with your install becomes your problem. You really don't want to fill some ones home with Co and cause sickness or worse. It's not worth it for the cost of an analyzer and a little training.

Jamie Hall

Think of it like an older car. It's amazing how far out of whack the engine can be and the old clunker still runs -- and how much better it will run if you put a little time and effort into tuning it up. Burners are like that: they will run and sometimes even look pretty good, despite being astonishingly far off.

Zman

I strongly recommend testing. You and your customers will rest easy knowing that everything is running perfectly.

It is a great way to set your self apart from your competition. If you make it part of your pitch, sighting the dangers of carbon monoxide poisoning, and your competition does not even know what a combustion analysis is, guess who Mom is going to hire?

https://www.youtube.com/watch?v=N5qpYSqkbLE&index=12&list=PLuuV0ELkYb5VE0I4evUZ30b5U78CRlRdg&t=0s

captainco

Not sure what the combustion numbers are in line means? They are not listed by most manufacturers. The efficiency on analyzers is 100% bogus.

Knowing the numbers and what they represent is just as important as having a combustion analyzer. Anyone working on combustion equipment today without an analyzer is no better than a unlicensed, fly-by-night contractor.

Manufacturers may prefer you don't use one because they may not want you to know how their equipment is actually performing.

HomerJSmith

I use a UEI C157 and chose it because of the extended life CO sensor(it werent cheap). Some of the newer meters allow you to purchase calibrated sensors that you can change yourself.

I don't pay any attention to the efficiency reading, I follow the manufacturers parameters. I can reach adjustment efficiencies of 95%, but when set up with the manufacturer parameters it reads 89%.

captainco

Just did a class with a company with the UEI analyzers. UEI has not updated their high efficiency calculations. Testo and Bacharach would read 98% efficiency when UEI reads 89%.

Manufacturers do not give O2 or Flue Temperature readings and most don't mention CO. They give you gas pressure at best.

I will say boilers and water heaters are factory set better than furnaces. Furnaces are rarely correct at factory settings. Combustion helps us set up the burner but measuring output:
CFM X Delta T X ADCF or GPM X 500 X Delta T and compare to input tells us they are performing up to their rating. However, faking the CFM or GPM also fakes the results, but that is how the manufacturers prefer it.

Which of these analyzer readings is the best:
O2 = 12% Flue T = 230 Eff = 82.2%
O2 = 10% Flue T = 260 Eff = 82.2%
O2 = 8% Flue t = 320 Eff = 82.2%

GroundUp

Thanks guys, lot of info here for a clown like myself. HTP, which I primarily use, has parameters in the manual for CO and CO2 which always come in within spec during analysis, so I'm told. Commercially is always Lochinvar or IBC and I haven't looked at a manual lately, but it seems to me they have the same parameters listed and also fall within spec 99% of the time. This is merely what I'm told, so I may very well be misinterpreting the information I'm given. As for the building being introduced to CO, how can that happen when the flue is power vented outside? Every single install is PVC vented to the outdoors.

Basically I'm asking what do you fellas need to adjust on startup, and what percentage of startups are adjusted? If there are no parameters in the manual, what do you shoot for? Also it'd take forever for me to justify the cost of something like a Testo 330 when my guy only charges 3% of that cost per analysis. I'm just a 1 guy company working nights and weekends so maybe 6-8 gas boilers a year. Is there a lower cost, basic unit that would be enough to perform a proper startup with no other bells and whistles? I don't do any service, strictly installation. Thanks!

NY_Rob

GroundUp said:

...HTP, which I primarily use, has parameters in the manual for CO and CO2 which always come in within spec during analysis, so I'm told. ...

You never know till you check it... it's a simple 10-15min test involving throwing two DIP switches. It's also part of the commissioning/sign off checklist to be left with the customer. You also need a manometer to record the static and running gas pressure readings at the gas valve.

GroundUp said:

Basically I'm asking what do you fellas need to adjust on startup, and what percentage of startups are adjusted?

On the HTU UFT series... there is just one screw used to adjust the mixture... right is rich, left is lean.

GroundUp said:

Also it'd take forever for me to justify the cost of something like a Testo 330 when my guy only charges 3% of that cost per analysis. I'm just a 1 guy company working nights and weekends so maybe 6-8 gas boilers a year. Is there a lower cost, basic unit that would be enough to perform a proper startup with no other bells and whistles? I don't do any service, strictly installation. Thanks!

If you only need CO and CO2, you can get a UEI C20 Combustion Meter. It's less expensive than the full featured Combustion Analyzers and it's got a 10yr sensor life expectancy. Of course it must be factory re-calibrated ($99) every year or so like every other CA.
You have to look at the boilers you install to see if you only need CO and CO2 readings.

GroundUp

@NY_Rob The EFT which is my go-to, as far as I recall only says 3.5-14"WC, 8-10% CO2, and 60-200PPM CO. That's about as vague as it gets, so what I'm wondering is what's ideal? Surely nearly every unit out of the box will meet those, not? Again I've never watched an analysis performed with any detail, only from a close distance so I know nothing of what is tested in a typical application

Zman

Almost every moderately priced analyzer measures O2 , CO, and temperature. That is all it does. It then internally calculates all the rest of the numbers it kicks out. The CO2 is a pretty straight forward to calculate. I agree with captainco, the efficiency number is a total WAG on most models.

For some reason manufactures love to write their specs for CO2 even though almost no one actually measures it.

I would say that most techs nation wide don't do analysis. Many techs that do, have no idea what the numbers mean. I had a super experienced commercial tech hand me a printout for an analysis on a boiler that read 14.2% O2 and 231 CO and he did not think anything was wrong.

I think the answer you are going to keep getting here at the nerd factory is "do a combustion analysis every time you install or service". Tell the customer why you do it and charge them enough to pay for the proper equipment.

Zman

captainco said:

Just did a class with a company with the UEI analyzers. UEI has not updated their high efficiency calculations. Testo and Bacharach would read 98% efficiency when UEI reads 89%.

Manufacturers do not give O2 or Flue Temperature readings and most don't mention CO. They give you gas pressure at best.

I will say boilers and water heaters are factory set better than furnaces. Furnaces are rarely correct at factory settings. Combustion helps us set up the burner but measuring output:
CFM X Delta T X ADCF or GPM X 500 X Delta T and compare to input tells us they are performing up to their rating. However, faking the CFM or GPM also fakes the results, but that is how the manufacturers prefer it.

Which of these analyzer readings is the best:
O2 = 12% Flue T = 230 Eff = 82.2%
O2 = 10% Flue T = 260 Eff = 82.2%
O2 = 8% Flue t = 320 Eff = 82.2%

@captainco
I love the way you broke this down.
How do you determine CFM?

captainco

Zman - Airflow is always going to be approximate whether you calculate it (blower specs way off) or measure it. Knowing that the 3 types of furnaces made require different airflows is the first things to know (most manufacturers don't know this).
75% = 100 cfm per 10,000 btu input approx.
80% = 130 cfm per 10,000 btu input approx.
90% = 150 cfm per 10,000 btu input approx.
But by trial an error in the field I have found if you measure flue temperature when adjusting blower speed, the lowest flue temperature will mean the airflow is close to the numbers above.

Airflow is to transfer heat and flue temperature tells us we are transferring the maximum we can. This works for GPM on boilers also, but they react much slower.

Airflow adjusted by flue temperature and Delta T is adjusted by fuel input not the other way around.

GroundUp

"Nerd factory" Hahaha I love it. Please excuse my feeble mind, but I still have no idea what an analysis means or does. If the readings meet the 60-200 PPM on CO and 3.5-14" WC on these EFT units, it's fine? Giving the printout to the customer just to show that it's been analyzed seems like a wasted expense to the HO I'd imagine, at least the ones I work for lol. They might as well use that paper to wipe their posterior, I can hear it now. There must be a certain mixture that one wants to achieve for optimum operation, and the parameters set by the MFG may be broad as the day is long. So what is it that we're aiming for? I apologize for my ignorance, but it makes zero sense to me so far

DZoro

With oil, and negative pressure gas valves (modulating boilers).

Without a doubt you must have a combustion analyzer. Without it is just a WAG, and unless you never plan on returning to fix a black sooted up mess in a few years, then don't bother with a analyzer.

These numbers represent your combustion status. Meaning how clean the current burn is. I'm not going into geek mode, there is training for that. Anyhow your instruction manual will give you exact numbers that you must achieve BEFORE LEAVING THE JOB. Those numbers will prevent poor system performance.

Years down the road with the set up numbers left inside the system you will be able to come back for your tune and clean, and confirm the numbers. Those numbers need to be present when you again leave that job. If they are not correct you have a problem.....
Low CO
High current uamps
CO2 in proper range high, and low fire........

Will give you a great running system and a happy customer.

Anything less than this is wrong and the job is just a fingers cross hope and pray soot don't come your way.
D

EBEBRATT-Ed

@GroundUp , everyone here wants to help.....but now you are just looking for an excuse not to buy and use a combustion tester.

So just flip the switch, start it up and walk away because everything done at the factory is 100% right?

You could have a bad heat exchanger
you could have a blocked flue
you could have a defective gas pressure regulator
you could have a combustion air blower that isn't up to speed
or it could be any one of 100 things

Let me ask you this. Explain to your customer that the reason they should buy a boiler install from you is that your price is cheaper because you don't do combustion testing. Also explain to them that you don't need to test because all equipment out of the factory is always 100% perfect. Make sure they understand they are putting their lives in your hands as a result of their cost savings

GroundUp

EBEBRATT-Ed said:

@GroundUp , everyone here wants to help.....but now you are just looking for an excuse not to buy and use a combustion tester.

So just flip the switch, start it up and walk away because everything done at the factory is 100% right?

You could have a bad heat exchanger
you could have a blocked flue
you could have a defective gas pressure regulator
you could have a combustion air blower that isn't up to speed
or it could be any one of 100 things

Let me ask you this. Explain to your customer that the reason they should buy a boiler install from you is that your price is cheaper because you don't do combustion testing. Also explain to them that you don't need to test because all equipment out of the factory is always 100% perfect. Make sure they understand they are putting their lives in your hands as a result of their cost savings

Although I appreciate your degrading negativity, none of what you just said has anything to do with anything that I asked. What I have asked several times now, is WHAT numbers are we looking for to achieve proper combustion? Never have I implied that factory settings are even close, much less perfect. I wouldn't have started this thread if I wanted an excuse not to buy a tester.

@DZoro , thank you. That helps a lot. This particular EFT unit that I frequently use however, has no "exact numbers" to aim for in the manual. This is the source of my confusion and apparent excuse to be a crappy contractor. Just wondering if there is a basic "one size fits all" recipe for proper combustion, seeing as some do not give any numbers to aim for. I have a Lochinvar Knight manual in front of my face right now and there is no mention of precise numbers in here either.

DZoro

Strange, I install the Lochinvar Noble series a lot. The numbers are in the set up manual. P 87 give a range and target numbers. Look possibly in the trouble shooting section?

Zman

Almost all boiler and burner manufactures print their specs. I have seen a few atmospheric models that do not.
There are general guidelines you can use for models with unpublished specs. Those specs vary depending of the type of equipment.

RPK

There’s a nice introduction to combustion analysis available here for free. It gives some general numbers for acceptable ranges for different types of equipment.

https://www.trutechtools.com/Downloads

GroundUp

Thanks a lot fellas, this has been very helpful. I gotta be on the road at 4am so it's naptime now, but I'll grab an EFT manual out of the box and take it with me to work to study. I've read this Knight one cover to cover 3 times tonight and found nothing, but didn't want to tear open a new box for the EFT manual. Curiosity has got me now!

SuperTech

I believe that on ANY fuel burning heating system that combustion analysis is the most important step in any installation. It's the only way you can be 100% sure that the equipment is safe to operate. It is considered criminally negligent in some areas to install or service equipment and not perform analysis. If you install or service equipment it is your responsibility to make sure it's safe. If you aren't testing, you are guessing.
Especially on new installation its crucial to record as many details as possible on how the equipment is performing, to establish a baseline for future performance comparison.
In my experience for every customer who doesn't care about combustion analysis there's more that appreciate that it's done. I love it when a customer smiles and says "I have never seen anyone do that before". Usually when I hear that the customer insists that I am their tech next time, and they are more inclined to follow my recommendations knowing that I put in the effort to make sure the equipment is achieving optimum performance.
In my experience the guys that I've worked with that don't think combustion analysis is necessary are usually hacks.
As far as what details of combustion testing to look for, its usually best to keep CO parts per million as close to zero as possible. This assures that you have complete combustion and the equipment is burning cleanly.

Steamhead

captainco said:

Anyone working on combustion equipment today without an analyzer is no better than a unlicensed, fly-by-night contractor.

THIS.

Forget efficiency numbers. Our first responsibility is to make sure the unit is operating SAFELY. We periodically hear about carbon monoxide events which kill people. Do we want to have to hire a lawyer because this happened to one of our customers? And likely lose the case because we didn't test the unit?

Just get an analyzer already. It's much less expensive than a lawyer. What the owner does with the printout is their business. as long as you provided it to them.

NY_Rob

You can always just aim for the middle of the mfg specs to be on the safe side in case it drifts off spec in either direction over time. If they accept between 8-10% CO2 at low fire- adjust the gas valve (turning it slowly and waiting 30sec or so for the reaction in the exhaust vent pipe) till you hit 9% CO. If the CO2 is below spec, make the mixture richer, if the CO2 is too high lean out the mix a bit till you hit mid range. It's good to run on high fire after the adjustment, then return to low fire to verify you're low fire reading is back at where you set it a few min ago.

Here's a video from HTP with a tech checking/adjusting the gas valve on one of their mod-cons..

https://www.youtube.com/watch?v=Hb8mWSTf9TM

captainco

There’s a nice introduction to combustion analysis available here for free. It gives some general numbers for acceptable ranges for different types of equipment.

https://www.trutechtools.com/Downloads

Sorry, anytime I read something that states vented equipment doesn't need to be connected to a flue I want to throw-up.
In 1992-1993 I did the AGA field test with AGA Labs. We tested 18 drafthood appliances in multiple locations and found 100% of them not venting properly and operating unsafe. In all cases there was plenty of draft in the flue, but because they were not connected the flues drew more cooler air than hot gases. Guess what percentage of CO poisoning and deaths are caused for the same reason . 90%+
Was Mexico the most recent?

GroundUp

captainco said:

There’s a nice introduction to combustion analysis available here for free. It gives some general numbers for acceptable ranges for different types of equipment.

https://www.trutechtools.com/Downloads

Sorry, anytime I read something that states vented equipment doesn't need to be connected to a flue I want to throw-up.
In 1992-1993 I did the AGA field test with AGA Labs. We tested 18 drafthood appliances in multiple locations and found 100% of them not venting properly and operating unsafe. In all cases there was plenty of draft in the flue, but because they were not connected the flues drew more cooler air than hot gases. Guess what percentage of CO poisoning and deaths are caused for the same reason . 90%+
Was Mexico the most recent?

I hope you weren't taking this as me saying I don't think they need to be vented. What I was referring to, was all new units that I install are vented with a new run of PVC, either to the roof or sidewall. I have never used an existing flue of any sort, so any harmful gases that may exit the unit are definitely expelled to the atmosphere.

Otherwise, much thanks all you guys actually trying to help. I'm pretty dense, so I appreciate your efforts to explain this to me very much! The links are very helpful also. Now, as for a cost effective means of analysis, do we have a consensus on the Testo 310? Seems like a fairly basic unit with (I think) what I will need and still budget friendly.

By the way I didn't get to that EFT manual yet, had to clean ash from the OWB this morning and was running late. Maybe a Sunday project!

SuperTech

I've used both the Testo 310 and the 320. The 320 is well worth the extra money, especially if you don't use it on every call. The 320 is much more user friendly.

New England SteamWorks

We always test. Have to. Though usually things are pretty close at start-up.

But not knowing is unthinkable...

Testo 330i with your phone is the only way to go. It's a brave new world.

RPK

> I hope you weren't taking this as me saying I don't think they need to be vented.

Captainco was referring to an issue with draft hoods.

If you search for a thread on heatinghelp titled “draft hood vs barometric” you’ll find a long discussion on this subject.

Rich_49

GroundUp said:

Thanks a lot fellas, this has been very helpful. I gotta be on the road at 4am so it's naptime now, but I'll grab an EFT manual out of the box and take it with me to work to study. I've read this Knight one cover to cover 3 times tonight and found nothing, but didn't want to tear open a new box for the EFT manual. Curiosity has got me now!

GroundUp ,

You gotta RTFM . Page 56 http://www.htproducts.com/literature/lp-387.pdf

Steamhead

Scares me that the venting table does not specify snow-line clearance, except to say the owner is required to keep the intake and exhaust openings clear of snow. That's a CO event waiting to happen.

Rich_49

Steamhead said:

Scares me that the venting table does not specify snow-line clearance, except to say the owner is required to keep the intake and exhaust openings clear of snow. That's a CO event waiting to happen.

But it does Steamhead .

LP-387 Rev. 011 Rel. 002 Date 2.26.18
34
NOTES:
A. For every 1” of overhang, the exhaust vent must be located 1”
vertical below overhang (overhang means top of building structure
and not two adjacent walls [corner of building]).
B. Typical installations require 12” minimum separation between
bottom of exhaust outlet and top of air intake.
C. Maintain 12” minimum clearance above highest anticipated snow
level or grade (whichever is greater).
D. Minimum 12” between vents when installing multiple vents.
E. 12” minimum beyond air intake.
F. Maintain 12” minimum clearance above highest anticipated snow
level or grade, whichever is greater.

Steamhead

OK, trick question. But you just proved my point. I'm talking about the table on page 30 that purports to show all the venting clearances. Those "notes" are a page or two later where they're not likely to be seen.

You or I would scrutinize all those pages. But from what I've seen, few others do. Here in Baltimore, I see a lot of PVC intakes and exhausts (don't get me started on whether PVC is a proper venting material) one foot above grade. We have been known to get up to three feet- not often, but we do.

CO events waiting to happen.

GroundUp

Rich said:

GroundUp said:

Thanks a lot fellas, this has been very helpful. I gotta be on the road at 4am so it's naptime now, but I'll grab an EFT manual out of the box and take it with me to work to study. I've read this Knight one cover to cover 3 times tonight and found nothing, but didn't want to tear open a new box for the EFT manual. Curiosity has got me now!

GroundUp ,

You gotta RTFM . Page 56 http://www.htproducts.com/literature/lp-387.pdf

Yeah, I read that. 30 times. And iterated several times above. There is no exact number to aim for. The parameters listed are very broad, and that's where my confusion was coming from. Someone mentioned to shoot for the middle of the road so it's safe if it deflects either way, which seems logical. I came here to learn something, not to be scrutinized by the veterans. I didn't realize it would be so difficult to get an answer as simple as "shoot for the middle of the listed parameters", unless that is not the correct answer.

GroundUp

I finished an install of a used, customer-sourced Triangle Tube Solo today and there is no exact combustion number there either. Only the broad numbers like everyone else.

SuperTech

It seems to me that gas fired mod cons don't require as strict combustion requirements as an oil burner, probably due to the fact that the firing rate isn't fixed, it modulates

Zman

@GroundUp
Why are you so bothered that the proper setting is within a range? There is nothing wrong with the instructions, you just get it within the acceptable range. Sometimes you shoot for the middle of the C02 range and the CO is a little high. You lower the CO2 and it fixes the CO. Nothing wrong with that.

Combustion analysis is the only way to tell if an appliance is running efficiently and safely. Get an mid range analyzer, take a combustion class and set yourself apart from the knuckleheads.

GroundUp

@Zman I am not bothered in the least by this. I started this thread to find out what to shoot for while listing the ranges that HTP gave and nobody besides NY_Rob bothered to mention that it's as simple as being within the range. Some say there is an exact number in each manual to shoot for, which is what I was concerned about because none of the manuals I've ever seen have given a precise number. It was apparently as simple as saying what you just said, but yet it was easier for the veterans to get derogatory instead of answering the question I asked. I thought this was Heating Help, not a place to get harassed for trying to better one's career. There seems to be a lot of differential in the answers provided above, so it would appear there is no "correct" answer.

I've got what I need, and thanks again to those of you who were helpful in answering my questions.

Zman

@GroundUp
Sometimes it is difficult to communicate complicated subjects via only text. I am glad you got your question answered.

Mike_Sheppard

I didn’t real through the entire thread again but I wanted to mention this. I think lots of manufacturers don’t mention super specific combustion numbers for multiple reasons. One being a safety factor (for them) and another being the vastly different conditions that burner could be under from one job to another. For example. A PowerFlame J Burner says 3-6% O2. That’s a fairly large difference. But let’s say that boiler runs year-round to also supply hot water via heat exchanger or indirect. If you tune that boiler up in the middle of winter when the boiler room is nice and cold, let’s say the boiler room is 40 degrees, and set the O2 for 3%, what’s going to happen when it gets warmer outside and the boiler room becomes 80+ degrees and that burner is still running to provide hot water? It’s going to go sub 3%, burn rich (less air density), possibly soot up the boiler, and create a possible dangerous situation with CO.

When I’m setting up a burner in those conditions, knowing that the boiler room temp changes a lot with outside temp, or if the burner is direct vented from outside, I will set the O2 up different for each scenario. On that burner in the middle of winter I’d be closer to 6% O2 while in the summer I’d be closer to 3% O2.

I don’t know how many people here deal with commercial burners or larger high efficiency boilers like Aerco and KN, but if you look in the KN manual it gives you VERY specific O2 numbers based on intake air temps. I guess it would be nice though if more burner manufacturers did that as well.