CO monitor going off near hot water

Specific Inspection Topics
1

Was performing an inspection. Was letting the oven heat up to check CO and turned on hot water. CO monitor started going off. Checked oven and it was fine. Hot water was registering anywhere from 10-110ppm, nothing with cold water. Checked multiple sinks all the same. House was vacant so I ran the hot water for 15 minutes, still reading CO… House was on a well and by the stains on the exterior appears to be pretty hard water. I use a Testo 317-3. I checked at my home and no readings at any sinks.

Any ideas?

2

What is the source heating the water?

3

Possible false alarm causes…
Here are a few situations that may cause a carbon monoxide “false alarm:”
The carbon monoxide alarm needs to be relocated.
Carbon monoxide alarms should be located 15-20 feet away from all fossil fuel burning sources like furnaces and stoves.

4

If you are confident your Testo 317-3 is functioning properly, you should most likely be concerned.

5

I cant think of any possible way that CO would be getting into the water, unless the water heater had a leak…

8

Natural gas water heater located in the garage

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9

Sounds to me like your oven is the issue. I assume you were testing ambient air, not undiluted oven flue CO.

For your personal CO alarm (edit), the first alarm level of ambient air CO is at 9ppm. 30ppm is the next level of alarm, requiring terminating the test. At 70ppm ambient air CO, exit the building.

I perform appliance undiluted CO testing during energy audits and test inside the throat of the oven at steady state. The first CO action level for an oven is 100ppm measured inside the oven throat (undiluted CO level). Recently I had an oven test at over 800ppm and still rising when I turned it off.

I think you misidentified the source of your CO; it’s probably the oven, not the water. In addition, was the water heater non electric and atmospherically vented? An atmospheric vented water heater could be another source of your CO.

No matter what, this is a serious issue that your client needs to know about and have fixed prior to occupancy. The risk of death is present in this home.

Good find!

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11

This is not the homes CO detector but my personal CO detector.

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12

It’s sulpher dioxide in the water. Often happens when the water is run for the first time on vacant homes.

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13

Good thought but It was not the stove, Im a BPI BA so I also regularly check ovens during energy audits and am familiar with the process.

I checked all water faucets in the home. They were all setting off my personal CO monitor.

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14

I’m assuming you mean hydrogen sulfide. If you have sulfur dioxide in your water, you got some real problems, lol.

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15

What I was thinking, too…but hydrogen

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16

You are correct.

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17

Finally. I’ve been trying all week.

And I agree with your assessment, the likely cause is sulfur/sulfide, etc.

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18

I had a job where hydrogen sulfide (from the water source) corroded the air handler and copper piping like Chinese drywall. Nasty stuff.

I’ve never CO tested water before, maybe the meter picks it up. You could research it or just mention it for further evaluation.

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19

Hmm, can I say that I was wrong without acknowledging that you are correct?

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20

Interesting. I don’t usually test water either normally, just had the detector on when i was checking the faucets.

21

Sorry, water (pardon the pun) under the bridge. I will be saving the below quote for future use though. :blush:

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22

I went through the same thing years ago. Someone answered my question on here when I asked. Apparently, I didn’t retain all of the information.

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(Sorry, had to try out my new favorite quote)

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