During regular maintenance of my furnace yesterday the CO measured at 70ppm, which is about 20ppm over what is considered ‘safe’. The technician indicated that he believes it to be caused by improper venting (too many elbows). This same company installed the furnace and venting 3 years ago, and I’m wondering (a) is this a likely cause for CO, (b) why wouldn’t this problem show up in any of the regular maintenance checks for the past three years, or even during the 30 years prior with the OLD OLD OLD furnace which also had elbows, and (c) if they didn’t vent it right the first time, should I trust them on the second? This is the same company that does commercial work for my father-in-law, and is one of the more reputable (and pricy) companies in the area. Their estimator (presumably a higher-up) is supposed to call me so I don’t know if this re-work will be free, but it will be discounted over what I would pay another company to come in and fix it.
I just want to make sure that I am fixing this problem correctly from the outset – I’m not really concerned (well, a little) with price. I can’t afford to mess around – my daughter is too little and precious. The furnace is right near her bedroom, and this is going to give me nightmares until it is resolved.
Thanks for any advice!
Replies
Where was the CO measurement taken? In the room air? In the flue itself? In the ductwork? (If all they did was measure in the ductwork, get another technician, preferably one with BPI CO Analysis training. A lot of people with CO meters measure in the duct work because that's the way they show 'em being used in the equipment catalogues!!!))
How long had the furnace been running when that measurement was taken? Was there one measurement or a series of measurements over time?
What were the flue draft readings? (Did they use a draft gauge?) Did the draft reading change when exhaust fans were run?
How many elbows? Elbows are a bad idea in flues. An older furnace may have vented properly because it was lower efficiency and more heat up the flue meant more draft to get past those elbows.
If it was a room air reading, 35ppm is the maximum permitted for brief periods (although note that there are several different standards.)
What kind of furnace? A naturally drafted, 80+ (has a blower on the front which leads into a metal flue pipe) or a 90+ (which also has a blower and leads into a plastic flue pipe.)
Are there any other gas appliances on the flue? Such as a water heater?
If it's an 80+ does the metal flue dump into a masony chimney? Was the chimney lined with a metal liner up to the top? Is the chimney in the center of the hosue or on an outside wall?
Is there sufficient combustion air in the utility area (50 cu ft/1,000 btu or 1 sq in of free vent space for evry 1,000 btu.) Does the furnace compete with the water heater and a dryer for combustion air?
Bottom line, did they do a full BPI protocol CO Analysis or were they winging it?
http://home.att.net/~cobusters1/coprotocol.htm
Get and use a good CO monitor - at a minimum get the type with a digital readout, if your daughter is an infant get a low level monitor - read about them and buy them at http://www.aeromedix.com
If there isn't a blower motor on the front of the furnace (it'll be about 6-8" in diameter, and lead to a 3 or 4" flue) then the furnace is naturally drafted and will have draft bonnet on the front: a box with an open bottom and the metal flue coming out of the top.
Are there dark stains on the outside of the draft hood? Bad drafting. Are there rusty swirlmarks on the inside of the draft hood? Probably bad drafting.
Keep us posted. Feel free to contact me by email
Bob Walker, BPI CO Analyst
Paradigm Inspections
NW Ohio
Edited 9/13/2002 6:11:16 PM ET by Bob Walker
Bob,
Thanks for your reply. My answer to many of your questions is "I dunno" - I wasn't in the room when he tested, but I will print this and your link out so I know what to ask when I talk to the company rep on Monday. The furnace is gas, 80% 2 speed, 75,000 btu with a metal flue (no masonry) that vents through the roof in the center of the house. There are 4 elbows between the furnace and the central flue, and one more elbow in the central flue. The furnace guy indicated that he thought this was the problem and we could probably get the 4 down to 2. There is a gas water heater on the same flue which was installed last year. The venting for the water heater always looked jury rigged to me, but I figured - they're professionals and I don't speak enough spanish to understand the answers to my questions. I had the company out today and the technician (a different guy) replaced the venting for the water heater - he thought it looked wrong too. Apparently the WH installer had put a reducer on it and that isn't allowed. Maybe I should switch to DIY on this stuff.
Is there sufficient combustion air? I think so, but it comes from the house rather than outside, which I know is not ideal. There was no provision made for combustion air when we moved into the house. We cut a hole in the door and put a vent in which should be enough (unless my water heater is > 213,000 btu).
I have a CO detector in my daughter's room, but I can see that it is insufficient. Thanks for the link to the site for better one.
Thanks very much for your input on this. I thought that buy hiring professionals that I would avoid problems like this. Of course I didn't have a headache before, but now...
Aimless--
Bob has already done a great job, merely mentioning an additional brand/make of detector, The Nighthawk, has a nice digital display and 9V battery backup, and to suggest placing a detector in the furnace room to sample the room air.
Regards,
Rework
Edited 9/13/2002 11:59:46 PM ET by Rework
Just as an update:
I purchased a digital low-level CO monitor from aeromedix and the room CO is displaying as 0 ppm - that's seems pretty good to me.
The 'plumber' (they actually license these guys?) came back and replaced the venting on the water heater with 3" galvanized pipe - something my HVAC guys say is a no-no. The 'plumber' swears it is aluminum, proving only that he can't tell the difference between one material and another - I know that shouldn't affect my estimation of his abilities, but it does. Since the plumber won't listen to me about what needs doing, I called my city inspector and asked him if he'd come take a look. He got here when the furnace guys were still working - they are amazing. Just kept right on going with an inspector looking over their shoulder, nodding and smiling pleasantly with any suggestion he made. He's going to double check the code (it has changed a couple times recently) and possibly give me ammo against the plumber to make him come back and fix his work again. He told me before he left, though, that plumber's tape is not a valid hurricane strap and the guy better get his butt out here to replace that!
Thanks again for all your help. I now have the name of a real plumber (from the HVAC guys) for when I rip it all out and start over.
The CO problem is fixed, and it turns out not to be the venting. Apparently, last year (after my usual maintenance), they came out and 'green-stickered' my gas appliances to account for the new gas mix in my area. The technician who did that set the low-speed wrong on the 2-speed furnace. That has been adjusted and I am now down to 2 ppm from 70 ppm. Bonus is that I should be burning less gas this year.
Again, thank you for your help.
"The 'plumber' (they actually license these guys?) came back and replaced the venting on the water heater with 3" galvanized pipe - something my HVAC guys say is a no-no. The 'plumber' swears it is aluminum"
Ummmm, most water heaters are vented with 3" galvanized; aluminum is not rated for venting water heaters (gas dryers, OK, water heaters, no.) Was that perhaps reversed in your message?
Good news on getting the CO levels down; and congradulations on getting the low level monitor - the bst choice, IMHO!
No it wasn't reversed. My local gas company has a best practices book that states aluminum is required, not galvanized. Even the plumber thought he was installing aluminum - he told me that he doesn't stock galvanized in his truck. The local code allows for galvanized, though, so I'm going to just leave it. So far I've had 4 people in trades who've seen my water heater and could not believe it was installed by a professional. The inspector stopped just short of calling him a hack.
Thanks again for your help!
Another regional difference, I guess,
Have either of the contractors done any draft gauge testing? Look for either aluminum tape covering a 1/4" hole, or a 1/4" hole plugged with a high temp caulk.
You can follow the flue rules and still get a poorly operating flue.