I've been doing HP assessments for 12 years, but find myself a little limited in my knowledge of this issue.

Here's the scenario: I do an initial assessment where I find a 7-year old NG water heater with 1500 ppm undiluted CO. The homeowner brings in his plumber to "fix" it. The plumber, who doesn't own a CO monitor, cleans the burner and air intake grill, and proclaims it good. After work is done on the home, I re-test and find the CO to be even higher this time, and the draft weak.

What typically can be done to a fairly new water heater to fix the CO problem? The gas/air ratio must be out of wack, I'm thinking. Is it usually corrected by replacing the gas control valve?

The homeowner is left hanging, the plumber is without a clue and me telling him it needs to be corrected. I would recommend a different plumber, but I want to find out what a knowledgeable individual would typically do to correct this, short of replacing it. One thing I know is I need to align with a knowledgeable person to address this in the future.

John Shillito

Tags: CO, heater, plumber, water

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I have to agree with Kurt. 2000 ppm is exceedingly high. I have tested hundreds of hot water heater (NG, Oil) and mostly they come in around 16 ppm. There is clearly something wrong and we all know that a gas hot water draft can easily be compromised. 

hey thanks for the links. Very informative on FVIR units

Hello John (and everyone else in the forum),

I'm a new visitor at this forum and it this is my first post. I look forward to more sharing and learning in the future.

The first condition that I would investigate the "weak draft". Is the flame lazy too? Is the equipment in place the same as what the flue was originally designed for?

I find the best place to contact when at a loss is the manufacturer's technical support.



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