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I know I’ll probably get some input here encouraging me to get rid of my unvented gas logs–period. But my house just isn’t all that tight, and I find them perfect for taking the chill out of a large living room. My question concerns a discovery I made during this mild winter about the controls.
Even on “low,” the room gets overheated before long. But I found that by positioning the dial between the normal operating range and “pilot,” I can get a perfect output that keeps the room just right. In other words, I’m not running them between “high” and “low;” I’m running them between “high” and “pilot.” My carbon monoxide detector continues to register “zero” as it always has, and I’d say the maximum time I ever burn the logs is about three hours. I know it’s always best to err on the side of caution with gas, but if the CO detector says all is well, is there anything else to worry about?
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Where is the CO detector mounted, high or low?
If low, is there a door or other opening where warm combustion gases can exit the room before cooling enough to get down to the level of the CO detector?
How old is the CO detector? They have a limited life expectency (although the life expectency depends on the type.)
Are you seeing carbon soot on the logs? If so, it's likely (not certain) that your also producing high levels of CO.
Is there a pile of bodies around the gas log set?
BTW, your log set is vented: it's vented into your living spaces. You are, in effect, living in a chimmney!
*Something I learned very recently:Most homeowner grade CO detectors register "0" until the CO concentration gets above 35 ppm. So even though your detector registers "0", if it's a typical homeowner model, you could be exposing yourself to a continuos low level (say 15 or 20 ppm) of CO which is dangerous also; long term.Just FYI.I don't offer any advice, other than I wouldn't do it personally. I'm just a diy'er, not a pro in the field. Were it my house, I would find someone with a commercial grade CO detector that will report all the way down to 0, just to satisfy my curiosity.
*I am a pilot and bought a CO detector for my plane that has very low sensitivity (I believe it triggers at 5ppm). The reason the residential CO detectors were increased to 30ppm is because fire departments were getting too many false alarms. You can try http://www.aeromedix.com/uses/aviation.html for a source of sensitive CO detectors. (be prepared to pay more than a residential CO detector)!!! I copied the following from their website:UL requires that they must not display CO levels less than 30 parts per million (PPM). Furthermore, they must not alarm unless exposed to 70 PPM for four hours, 150 PPM for 35 minutes, or 400 PPM for 15 minutes! These requirements were imposed by UL at the request of gas utilities and firefighters to minimize the number of unnecessary emergency 911 call-outs from homeowners. (Yet most fire departments require that firefighters put on their oxygen masks if CO levels are 35 PPM or higher ... go figure!)
*Dear John,Yes, there are many other things to worry about with indoor combustion. Bob is right about living in a chimney. Chris is right about dumbed down CO detectors. And Jim is right about the fallacy of the UL listing on these dumb alarms.I don't want anybody to have to live at 30 ppm CO. But that's just the start. There are also sulfates, nitrates, aldehydes, more toxic organics, and a host of nasty soot particles.It's all bad and running your unit out of the normal fuel flow boundaries makes everything worse. Without enough fuel, or fuel velocity in the burner, the flame shape can be corrupted. These effects are unpredictable and subject to sudden changes. In worse case scenarios, this will wreck the equipment, or soot the burner, or produce very dirty (read: toxic) combustion. Again this can go from bad to worse every time you fire it up.Trying to be scary, Fred
*I'd rather be scared than dead, so thanks, gentlemen, for your replies. I'm glad I asked if only so others can read the alarming information about CO detectors. I knew my gas logs were potentially dangerous; I didn't know the device I bought to minimize that danger was also a threat. Many thanks. John
*Dear John,Death is rarely the issue. With low level exposure, people just sicker more often and have less energy. It mostly takes down the quality of your life a notch. Glad to see you take it seriously.Regards, Fred
*The AIM 935 Low Level Carbon Monoxide Monitor is no longer being manufactured! Boooo!My understanding is that the current digital readout types start to display at 30 ppm.FredL is absolutely right about all of the other wonderful things in combustion gases.Also, as he said: "Death is rarely the issue. With low level exposure, people just sicker more often and have less energy. It mostly takes down the quality of your life a notch."I will disagree to the extent that prolonged exposures to lower levels can sometimes take your quality of life down a lot more than a notch.I regularly communicate with people who have been effected by long term low level exposure and their lifes can be horrible: major neurolgic problems, heart problems, all sorts of serious nasty stuff. Those effects can last for years - it's not just a headache that'll go away with a few bretahes of fresh air!I agree 100% with FredL's comment: "Glad to see you take it seriously."FWIW, there is no consensus about waht a "safe" lower limit is, and like everything else, will vary from individual to individual: people most at risk are : pregnant women, infants, elderly, immune system compromised type, people with heart conditions, people with other chemical sensitivites, people with prior CO poisoning experiences.Just because you aren't dead doesn't mean you don't have a CO problem!
*Bob,The AIM that you mentioned is the same model that I have in my plane. It is no longer in production, but if you look at the url that I listed above, there are two new models available from other manufacturers. One is $75 and the other is $125. I forget what I paid for the AIM, but it was in that general price range. The AIM is good for 3 years. I have not looked to see what the life is for the new low level detectors.BTW, When I learned about the UL rules for residential alarms, I put my AIM CO detector in the house from time to time, and it has never indicated anything above zero :) If you have any pilot friends, you might ask if they have low level alarm you can borrow for a few days./Jim Pappas
*Jim,Thanks for that info about the other low level CO detectors. That aeromedix site gives one of the best, succinct summaries of CO that I've read! Required reading, folks!I have 3 AIM 935's, I keep one on the end of my tool box (I'm in 3 houses a day, 4 2/3 days a week and see some furnaces/boilers you wouldn't believe!) one in my bedroom, and one in the hall outside the kids' bedrooms at my ex's house.I had been recommending the AIM 935 for clients (homebuyers - I do home inspections) with family members who are at risk (mainly pregnant or with infants.) It's good to know there are alternatives!