Carbon monoxide in flue gas

MAD

whats the max level of carbon monoxide in flue of gas boiler cat. 1

Tim McElwain

ANSI Standard states

allowable 400 PPM in a flue sample air free. We strive to stay below 100 PPM on both gas and oil. Anything above 100 PPM unless specified by the manufacturer needs adjustment of either air or fuel or both. In some cases other things can cause high CO such as impingement of the flame on a cooler surface etc.

Steve Whitbeck

No code

Last time I checked there isn't a code for maximum amount of CO in vent gasses, BUT there is a paper that reccomends 400 PPM or less. This paper has NO authority over the trades. If is just a suggestion.

Mark Eatherton

Max allowed, or max that can be seen?

Tim addressed the maximum allowed. As for maximum that can be seen, I've pegged my meter (and immediately pulled it out) at 10,000 ppm in a terribly fouled boiler.



Steve, ANSI is recognized by the code authorities as an approved standard making organization. If they recommend a certain standard, and that standard is recognized by the AHJ, then it is the same as the AHJ having asked for it. They typically refer to the agency by Name and Standard #.



The old standard of 400 ppm was set to compensate for ovens. If you have an appliance running at 400 ppm, you've got a sick appliance on your hand that is in need of service. Ovens impinge flame on a spreader plate, thereby quenching the flame and producing excess CO, hence the higher standard for allowable ppm.



Tim, feel free to correct me if I've mis-spoken about the ovens.



MAD, take as many courses as you can get. I know that TIm puts on a great class, and Jim Davis also puts on classes throughout the country. You can't learn too much as it pertains to the production and elimination of carbon monoxide.



ME

Tim McElwain

The ANSI standard

of 400 PPM is for furnaces, boilers and water heaters.



Hard to believe but for gas ovens it is 800 PPM. I have always worked at keeping ovens down below 25 PPM. It is not unusual when in the self cleaning function of gas ovens to see 500 to 800 PPM. You will even get CO with an electric range on self cleaning. I will always check ovens in peoples homes when there on a service call for heating or water heating as a service to protect life.



These standards remember are called allowable and take in many considerations. I would never leave anything running at 400 or 800.



There are ANSI standards for everything in our business and they are recognized by authorities having jurisdiction as Mark spoke of. In fact the National Fuel Gas Code NFPA 54 is also ANSI Z223.1.

Mark Eatherton

Thanks TIm...

I will update my memory banks :-)



ME

Steve Whitbeck

Mark

Last time I checked was a few years ago - I had a situation where the CO level was high on a realty boiler inspection. I red flagged the boiler ( Slantfin ). In the past I tried to clean Slantfin boilers and it didn't help. so I told them it needed to be replaced. They wanted some code showing max CO in vent pipe. Talked to the LOCAL mechanical ( hydronic) inspector and He told me there wasn't any code BUT there was a suggestion. ( that is where my coment came from)  Seems they are taking that suggestion as law now.



Steve

Steamhead

Was this Slant/Fin

gas or oil fired?

Tim McElwain

It has been my

experience over the last 50 years that many in the trade including inspectors are not familiar with ANSI standards. Those standards by the way determine how a piece of equipment gets tested by a third party test facility (UL, ETL, CSA etc.) The list of those standards can be found in Annex M of NFPA 54 M.2.2 CSA America Publications. Most of the gas appliance are under the Z21 label. For example Z21.13/CSA 4.9 Gas-Fired Low Pressure Steam and Hot Water Boilers 2004. They hold the same power as any of the Codes such as International Fuel Gas Code which we use in RI, or NFPA 54, IAPMO Codes etc. They are not LAWS, they are CODES and there is a big difference when you get into court. The judge will often at the beginning of a case make the following statement, "For purposes of this trial section such and such of NFPA 54 will be considered as law, at the conclusion of this trial it will however revert to CODE."

EGGIEKEN

CARBON MONOXIDE IN FLUE IN VERMONT

I HAVE READ WHAT IS ON THE WALL ABOUT FLUE CO LEVELS AND AM STILL UNCLEAR.  I HAVE A CONDO IN VERMONT WITH A BOILER THAT SERVICES MY UNIT ONLY THAT WAS TESTED BY THE CONDO ASSOCIATION FOR CO PPM, THEY FOUND IT TO MEASURE 334 PPM AND SHUT IT DOWN, SAYING THE MAXIMUM IN VERMONT ALLOWED FOR THE FLUE GAS IS 100 PPM.  I HAVE CLEANED AND MADE ADJUSTMENTS TO THE BOILER AND NOW IT MEASURES 133 PPM. IS THE "CODE" OR "LAW" 400 PPM OR NOT.  AM I OK TO CONTINUE RUNNING MY BOILER IN VERMONT ?