Jump to content

How much CO can a pilot light put out


Steve Knight
 Share

Recommended Posts

I saw this flue on an older GSW power vent water heater today. While the water heater has a power vent, it still has a draft hood. When I got inside and started up my Monoxor II it read 5ppm. I took it outside to check calibration and it went back down to 0. Back in up to 5. Whole house was at 5ppm. There was a significant back draft occuring at water heater flue. There was virtually no wind, but outside temp was 20 degrees below indoor temp. Back drafting was causing CO from pilot light to flow back into house. A return air duct was located just outside mechanical room and seemed to be spreading CO throughout the whole house.

Download Attachment: icon_photo.gif water heater flue.JPG

102.91 KB

Link to comment
Share on other sites

It might be what you said, & it might not. I find it a little hard to believe that a single standing pilot could create 5ppm throughout an entire house. I'd be looking for other sources.

I've had many similar experiences w/ this kind of reading; it's why I don't use a CO monitor for much of anything anymore. It boils down to protocols. If you aren't spending about 45 minutes to an hour performing a full blown testing protocol, you might as well toss all the readings out. Until you do it the "real" way, you might be chasing red herrings.

You found a problem, which is the backdrafting water heater. Report it & advise that it be repaired. All the CO readings & "testing" tend to obfuscate the important finding; the water heater is backdrafting.

Link to comment
Share on other sites

Originally posted by kurt

It might be what you said, & it might not. I find it a little hard to believe that a single standing pilot could create 5ppm throughout an entire house. I'd be looking for other sources.

I've had many similar experiences w/ this kind of reading; it's why I don't use a CO monitor for much of anything anymore. It boils down to protocols. If you aren't spending about 45 minutes to an hour performing a full blown testing protocol, you might as well toss all the readings out. Until you do it the "real" way, you might be chasing red herrings.

You found a problem, which is the backdrafting water heater. Report it & advise that it be repaired. All the CO readings & "testing" tend to obfuscate the important finding; the water heater is backdrafting.

Solid advice. More often than not in our business, less is really more. The less you say the more effective your comment. This is a potentially serious finding and the low CO readings really do dilute the effectiveness of any warning you issue on your clients' behalf. Who knows what the readings will be next week or next hour after the heater itself runs under demand for awhile.

Link to comment
Share on other sites

I still don't think 5PPM is anything to be concerned about. I grew up in a home that had an unvented gas stove with a pilot light burning 24/7/365. Not even once was anyone in my family ever affected by that pilot. When that water heater lights off, the interlock will kick on the fan and it will draft fine. If it didn't then I'd be concerned.

ONE TEAM - ONE FIGHT!!!

Mike

Link to comment
Share on other sites

If I remember the classwork correctly, it takes 50ppm for 8 hours to make one "feel" anything.

That said, different folks have different sensitivities, & really strange stuff can happen. I performed an inspection approx. 7 years ago where I found a mid-efficiency furnace that wasn't vented adequately; the discharge was blowing across a roofline & entering an attic dormer window. When I tested the attic, I found somewhere in the vicinity of 800ppm, enough to kill someone in about an hour. I have no idea now the CO was able to concentrate itself in this corner of an attic. No one else could figure it out either.

Point being, 0ppm is what we want. I understand the part about 5ppm not being dangerous, but 0ppm is preferrable.

Link to comment
Share on other sites

Originally posted by Steve Knight

I saw this flue on an older GSW power vent water heater today. While the water heater has a power vent, it still has a draft hood. When I got inside and started up my Monoxor II it read 5ppm. I took it outside to check calibration and it went back down to 0. Back in up to 5. Whole house was at 5ppm. There was a significant back draft occuring at water heater flue. There was virtually no wind, but outside temp was 20 degrees below indoor temp. Back drafting was causing CO from pilot light to flow back into house. A return air duct was located just outside mechanical room and seemed to be spreading CO throughout the whole house.

But did you test the CO at the draft hood?

If the pilot is causing 5ppm throughout the whole house, that's a hell of a balancing act. I think it's something else. Good hunting. It should only take a few weeks to figure it out.

BTW, just for fun, I measured the CO in my water heater's flue with only the pilot on -- 2ppm.

Then I lit a candle from our blackout kit and measured the air ten inches above it -- 26ppm.

There are lots and lots of things in addition to the water heater that you should be suspecting.

(Did you ever measure the CO emitted by an electric oven during its cleaning cycle?)

- Jim Katen, Oregon

Link to comment
Share on other sites

Originally posted by Jim Katen

(Did you ever measure the CO emitted by an electric oven during its cleaning cycle?)

I haven't tried that, but I do include a warning about it in my report. Most people have no idea the cleaning cycle does that (good "Gee whiz" value).

I did a little 900 sq. ft. house over in Bama last winter. I wasn't there 5 minutes when my CO Experts alarm started beeping in my bag. I got a steady 50 PPM reading in there. The whole house was heated by one big butane wall heater. How many days and nights were they living in 50 PPM? The lady said the little girl (7) "had the flu a lot". When I told what it probably really was she looked sick.

Brian G.

Link to comment
Share on other sites

Hello All! I'm new to this forum, and new to the Home Inspection field. But I've worked for a natural gas company for 20 years, and we've been trained to start looking for any sources of co producers when we see 5ppm on our instruments.

There could have been any number of reasons for 5ppm...is there an attached garage, and did they just move the car out? Did they allow the garage to vent before closing it? Is there a smoker in the house? Do they live near a highway? Do they have pilots on their range & in their oven, and have they been cleaned/checked lately? (BTW, ovens should be cleaned and checked by a professional appliance repair company-too much to go into at this time). Are you sure it wasn't a sump pump battery that is discharging? Those can give false readings as well. These are all things to look for, when an instrument picks up co.

Gordon

Link to comment
Share on other sites

Exactly why a "simple" CO test is worthless.

Does anyone else think that hiring a professional appliance repair man to clean the oven is possibly over the top? The only danger I've experienced when using the Clean cycle on my oven is when I didn't turn on the exhaust fan. Is it really dangerous to clean your oven?

Link to comment
Share on other sites

____________________________________________

Does anyone else think that hiring a professional appliance repair man to clean the oven is possibly over the top? The only danger I've experienced when using the Clean cycle on my oven is when I didn't turn on the exhaust fan. Is it really dangerous to clean your oven?

________________________________________________

Kurt...sorry, guess I wasn't clear enough. Have to remember to be a bit more detailed here. I was thinking of a range that has standing pilots to it, not electronic ignition. Since an oven pilot burns right up against the burner, the carbon it produces can clog the portholes, and cause a delayed ignition. Most people don't know how to clean the pilot/burner area properly, and the best advice I've given people is to have an appliance repairman inspect/clean it for them.

You're right when you say it might be overkill...but after seeing so many people try things on their own, and making a bad situation worse, I found it best in this case to err on the side of safety.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...