High CO readings from old Oil Boiler.Should I be worried?

[bman03]

I had my (1400s sq ft; 2 floor) house reviewed for energy efficiency recently. The guy stuck a probe in the flue of my oil boiler and gas water heater. He showed me Carbon Monoxide levels from the water heater was reading 10ppm and the boiler was 340ppm. He said the boiler was way over the acceptable level (100ppm) and I should call someone for a tune up. I have a service contract with my oil supplier and they come every year for "tune up". So I called them and that guy checked the flue venting with a meter and looked at the flame in the boiler. He told me that there was nothing wrong with the boiler and if there was too much CO I would see it as soot or black flakes in and around the boiler. He told me there's nothing wrong, not to worry, and left.
I don't know what to think now. The boiler is a Williams Oil-O-Matic and by it's name I'm guessing it's at least 30 years old. Is 340ppm an unreasonable amount of CO for a boiler of this age? Is there something wrong that needs fixing?

[Jim Davis]

Yes, there is something wrong and it is potentially dangerous. CO does not cause sooting all the time. I have seen equipment making 1000's of ppm without soot. Unfortunately you have one guy that tests for CO but doesn't know what it means and another that doesn't test at all because he is not concerned with your safety. 100ppm is a maximum for proper operation but 400ppm is legal. However if it goes uncorrected it will not stay at 340ppm. High CO and no smoke on an oil furnace may mean it is way underfired and isn't hot enough to burn all the fuel. Oil starts out as a liquid, is converted to small droplets through the nozzle and then becomes a gas or vapor in the heat exchanger and then it burns. Too many vapors are not burning and that is not proper. You could eventually end up with a soot problem and a mess. Right now I am guessing the efficiency of the furnace is really low, but without a flue temperature, O2 or CO2 reading and a supply air temperature it can't be calculated.

Until the CO is below 100ppm there will be a worse problem on the horizon.

[tipsrfine]

Did the boiler guy even have a CO analyzer? Or did he just "look at it" and say it is fine? You may want to shop around for a better boiler guy.

[bman03]

tips - The boiler guy had some sort of meter. After inserting it into the flu vent, he mentioned that my venting was good. Based on those indicators, I'm guessing it was some kind of airflow meter. He never mentioned the level of CO from any of his equipment. He literally opened a door on the boiler, looked at the flame, and told me that it looked fine.

Jim, so what I'm concluding is that 340ppm for an oil boiler, regardless of age, is not appropriate? I don't understand how 100 can be the max for proper operation but, 400ppm is legal. Since I'm at 340ppm does that mean the boiler is working as expected? Is it not worth me trying to get someone to fix it?

[jtrammel]

tips - The boiler guy had some sort of meter. After inserting it into the flu vent, he mentioned that my venting was good. Based on those indicators, I'm guessing it was some kind of airflow meter. He never mentioned the level of CO from any of his equipment. He literally opened a door on the boiler, looked at the flame, and told me that it looked fine.

Jim, so what I'm concluding is that 340ppm for an oil boiler, regardless of age, is not appropriate? I don't understand how 100 can be the max for proper operation but, 400ppm is legal. Since I'm at 340ppm does that mean the boiler is working as expected? Is it not worth me trying to get someone to fix it?

You need to get it fixed, 100ppm is the max it should ever get and if it gets above 400ppm the unit has to be shut down until the problem is corrected or furnace/boiler is replaced. You are at 340ppm which is still legal to operate but dangerously close to the illegal limit and very inneficient (wasted a lot of oil you are paying for at a high $$$)

[beenthere]

WAG. The guy that have been cleaning your boiler are trying to save you money on your heating bill. And have been down firing your boiler. It is now so low that the combustion air can't be controlle properly by teh burner/end cone/retention head, and its too much air, and causing the high CO. Which means your not getting all the heat from the oil you should be.

[kangaroogod]

The short answer is that a full combustion analysis should be performed and the burner should be tuned for maximum efficiency within safe levels. If the contractor did as you said then I would use another. The one that was there is either not qualified or does not care for YOUR well being. I would find one that meets both criteria. I would guess you have a company that merely changes the nozzle/oil filter and does a quickie on the flue ways. A professional that cares for you as a customer will change the oil filter, nozzle, strainer (secondary filter) inside the pump, dismantle the unit and thoroughly brush the flue passages, remove the vent pipe and clean, check the chimney condition, check the oil pressure, confirm the proper nozzle is installed, check and adjust your draft through the boiler, adjust the oil/air ratio with digital instrumentation while also measuring carbon monoxide. This wiuld take 1.5-2.5 hours or more. This would be an absolute minimum that needs to be performed in addition to all other water end checks of the boiler.... Good luck in your contractor search

[Jim Davis]

See below

tips - The boiler guy had some sort of meter. After inserting it into the flu vent, he mentioned that my venting was good. Based on those indicators, I'm guessing it was some kind of airflow meter. He never mentioned the level of CO from any of his equipment. He literally opened a door on the boiler, looked at the flame, and told me that it looked fine.

You have to understand we have antiquated standards that date back to the 1920's. Having done field testing for 35 years with combustion analyzers the 100ppm is a number that established itself. It is a small number in flue gas but a big number in the ambient. I just know that an oil furnace running at 340ppm is not running safe or efficient. Oil is too expensive not to have someone that is really proficient using a combustion analyzer on oil. There are 15 different and specific CO patterns on oil equipment that indicate different mechanical problems. These have to be corrected before the maximum efficiency can be dialed in.

Jim, so what I'm concluding is that 340ppm for an oil boiler, regardless of age, is not appropriate? I don't understand how 100 can be the max for proper operation but, 400ppm is legal. Since I'm at 340ppm does that mean the boiler is working as expected? Is it not worth me trying to get someone to fix it?

[bman03]

Thanks guys. I'm glad to know there are professionals out there. Unfortunately for me I still need one. I checked the Contractor Map and there isn't one in my area. The closest one is 40 miles away and they don't do oil. The closest ones who do oil are 80+ miles and they don't service my area. Anyone know where I can find honest, knowledgeable, pros like you guys in the Boston\Metro-West area?

Thanks,
Brian

[Jim Davis]

You might try Waldman Plumbing, they are not too far. They work on oil. 781-593-7490.

Tell them Jim Davis gave you their name. They are all CO/Combustion Certified.

[bman03]

Thanks Jim. I will look them up.

[udarrell]

The short answer is that a full combustion analysis should be performed and the burner should be tuned for maximum efficiency within safe levels. If the contractor did as you said then I would use another. The one that was there is either not qualified or does not care for YOUR well being. I would find one that meets both criteria.

I would guess you have a company that merely changes the nozzle/oil filter and does a quickie on the flue ways.
A professional that cares for you as a customer will change the oil filter, nozzle, strainer (secondary filter) inside the pump, dismantle the unit and thoroughly brush the flue passages, remove the vent pipe and clean, check the chimney condition, check the oil pressure, confirm the proper nozzle is installed, check and adjust your draft through the boiler, adjust the oil/air ratio with digital instrumentation while also measuring carbon monoxide. This would take 1.5-2.5 hours or more. This would be an absolute minimum that needs to be performed in addition to all other water end checks of the boiler.... Good luck in your contractor search

Excellent instructive post, kangaroogod.

The combustion chamber is sized for a proper combustion firing at somewhat narrow perimeters, so that the refractory effect of the combustion walls get it hot enough to burn all the fuel plus a lot of the hydrocarbons.

A smoke reading with oily or yellow spots on the filter paper is a sign of unburned fuel, indicating very poor combustion, which could produce high emissions of carbon dioxide & unburned hydrocarbons

Additionally, on older burner units, especially if they've been down-fired or, (on those that have inlet strainers) plugged fuel strainers in the pump inlet that's lowering fuel input to the nozzle, they could have too much combustion air entering the combustion chamber which cools the combustion temperature too much; causing incomplete combustion & higher Carbon Monoxide levels.

Closing down somewhat the combustion air inlets so there is just a trace of smoke on the filter paper might help clear up that problem, as combustion will be considerable hotter. If down-fired too much, the heat refractory reflection will be inadequate, again resulting in incomplete combustion & burner inefficiencies.

[bman03]

FWIW

I called my oil company again to follow up on the annual service they (should have) provided and they forwarded me to the manager. He tried to convince me of two things: 1) "No one ever died from carbon monoxide using oil heat" 2) "Oil heat does not produce carbon monoxide like natural gas does".
Yes, those are quotes.
I can't confirm #1. #2 is technically true since unburned natural gas is not the same as home heating oil. However, it seems as if he's either ill-informed or he's trying to pull one over on me.