Comments on: Can a Single CO Reading Really Confirm Combustion Safety?

By: Daid Richardson

Daid Richardson — Tue, 08 Mar 2011 17:55:16 +0000

My apologies in taking so
My apologies in taking so long to respond to you all, thank you for all the comments.

John there is a set of guidelines for how the testing is to be performed on multiple test locations such as would be the case with a natural draft furnace.
The easiest way to do this is just as you would read a book going from left to right. Starting in the first heat exchanger cell outlet you would take a reading during the run cycle for close to 30 to 40 seconds or once stabilized and then move to the second cell outlet obtaining a sample there for 30 to 40 seconds again.
The process repeats again till you have one set of numbers for each heat exchanger cell outlet then the process is repeated again till there are three readings taken per cell. This will help in determining the stability of combustion.

Jim you are absolutely correct about Jim Davis being an impact in my life on this. I am fortunate enough to be the first person that Jim has passed the torch to for teaching his life's work. It's good to know you know the history between Jim and BPI, their standards have changed much since he first gave input on them many years ago. My hope is that they will move back towards so many of the important concepts that seem to have been forgotten.

Paul you are right about the air-free CO readings needed for ovens in regards to ANSI standard Z-21. The BPI standards from what I gather are designed around 100 PPM of CO as read on the analyzer which in my humble opinion is too high. 50 PPM as read should be the most any gas oven produces.
This rule helps give auditors a number to shoot for if they are using a CO only test instrument or if the Oxygen sensor in their combustion analyzer goes bad.

One thing about CO air free is that it is a calculated number being figured on the analyzer and it has a chance of being off depending on certain variables.
In my opinion sticking with 50 PPM as read gives all auditors a useful reference when making these checks in the field.
In every class I teach the numbers to be used for diagnostics are as read CO numbers.
Air free numbers are important for code compliance and have their place in that regards.
It is much easier from what I have found to use as read numbers when performing diagnostics in the field.

Thanks for all the comments and great discussion!

By: Paul Raymer

Paul Raymer — Sun, 27 Feb 2011 01:54:00 +0000

There is ongoing confusion
There is ongoing confusion about undiluted and CO Air Free readings using combustion analyzers. Since analyzers provide both readings from a undiluted sample, which reading is the one that BPI references? John Jones of BPI says, "Ovens and all combustion appliances with exhaust vents (pipes) should be tested using the air-free method (setting)." If the auditor is using a basic CO measuring device like a Monoxor that doesn't have an COAF setting, this would mean that they would be getting the wrong information. Is that correct?

By: Jim Tenhundfeld

Jim Tenhundfeld — Sat, 26 Feb 2011 20:21:31 +0000

You have obviously been
You have obviously been influenced by Jim Davis and you are absolutely correct. Constant monitoring of CO and O2 can tell an analyst a great deal about the operation of the gas appliance. However, BPI is not listening. They used to when Jim was their first instructor.

By: John Poole

John Poole — Wed, 23 Feb 2011 21:19:26 +0000

Important information, David.
Important information, David. Thanks for posting. Do you happen to have any guidelines for multiple tests. E.g., number of tests, time between samplings, etc.,? Was just wondering. Thanks again!