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Candles and CO

Anyone ever run into a situation where scented candles set off a CO detector? Son lives in a place where the CO detector will register 10 ppm and then one time 42.
Has Gas FHA heat.
Tech came out out found nothing.
He has taken my Testo out 2 times and nothing....

The candles came up in a passing conversation....


  • STEVEusaPASTEVEusaPA Member Posts: 4,143
    I never checked with an analyzer or meter but have to assume it's entirely probable.
    Anything else (chemicals) possible giving a false reading to cheaper CO detectors?
  • kcoppkcopp Member Posts: 3,499
    I will ask.
    They have 2 detectors. 1 up, 1 down. The upstairs has never gone candle(s) up there either.
  • Jamie HallJamie Hall Member Posts: 12,864
    There is no reason why a candle wouldn't produce some CO. Uncontrolled combustion of carbon containing compounds. Ditto wood fires. The question is -- is it enough to worry about? You should be able to measure it, given a sensitive enough detector in the updraught from the candle, but... really now...

    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Tim McElwainTim McElwain Member Posts: 4,365
    Scented candles can give off as much as 15 to 25 PPM. Use beeswax candles as they are safe. Sorry now I ruined your romantic evening
  • Bob HarperBob Harper Member Posts: 835
    When a jar candle gets down into the jar, its gets harder to drawn fresh O2 in but the jar fills with CO2, which is heavier than air and displaces O2. This insidious cycle results in increasing levels of CO from incomplete combustion. Untrimmed wicks and the composition of the fuel also factor.
  • captaincocaptainco Member Posts: 451
    Considering the btu value of candles is quite low, it would be unlikely that a candle could create very high CO readings in the space.
  • LeonardLeonard Member Posts: 903
    edited February 2019
    Suppose it depends on size, number of candles, and how long you burn them. Plus size and how tight the room is.

    PBS TV show "queen VICTORIA", ~ 1840's , shows 20-300+ candles burning. But they also had fireplaces, that acted as LARGE exhaust fans.

    For mosquito control outside I make my own LARGE candles, burns with 1 inch wide by 2- 4 inch tall flame. I burn 2 or 3 of them outside in the yard. Helps a lot, just regular wax ( old 1/2 used scented candles people throw out)

    To make them.....I take a 1 foot diameter glass salad bowl, put in a wick made of kitchen paper towel , folded to ~ 1"x 1/8" cross section, then add chucks of wax from old candles , then melt in extra wax with propane torch to fill the spaces between chunks.

    Makes me wonder how much CO those old kerosene lamps with 1 inch wide wicks made. I've used a few outside at nightime dinners.
  • NY_RobNY_Rob Member Posts: 1,370
    Leonard said:

    For mosquito control outside I make my own LARGE candles, burns with 1 inch wide by 2- 4 inch tall flame. I burn 2 or 3 of them outside in the yard. Helps a lot, just regular wax ( old 1/2 used scented candles people throw out)

    Just kind of curious... where do you find "old 1/2 used scented candles people throw out" ?

  • LeonardLeonard Member Posts: 903
    edited February 2019
    Here in a BIG city 100k+.....When the economy was better people used to throw out a lot of GOOD stuff on the curb on trashdays. Or when they moved in springtime ( didn't want to pack it all up). Usually only find 2-6 jars at a time, but twice found box full of them. Or shoebox full of 1/2 burnt candle sticks. Even once few cardboard boxes of big chunks of attic melted new raw wax slabs. Craigslist free ads too.

    Also some goofy scented candles that people didn't like..... but it's all fuel for outside use. I put them 10 ft from me when I'm working on the car and get few mosquitoes and no smell.

    Especially in richer areas, or high rent apt complexs, working electronics too. Got my fancy wide screen Sony TVS , Audio amp, speakers, TIVO, DVD player, MW, VCRs that way. 10 hp Snowblowers needed a little work. Computers for parts or use. Took a few years to accumulate all of it. Amazing what rich people throw way.

    Instead of expensive torch lamp oil, some #2 heating oil works too, I cut it with with ~ 1/3 old gasoline to increase flamability and stop the 3 inch long oily soot threads. ( YES ... I do test for no match flamability of liquid mix for safety)
  • kcoppkcopp Member Posts: 3,499
    Since they stopped the candle use they have not had an issue.... What is the chance that the odor/scent will trigger a false reading?
  • Jean-David BeyerJean-David Beyer Member Posts: 2,663
    During tropical storm Sandy some years ago, the power went out for 6 1/2 days here. It got mighty cold. That was what inspired me to get a backup generator.

    I lit 6 or 8 candles in my bedroom and shut the door. After an hour or so, the temperature of the room even went up a degree or two. But my high sensitivity CO detector alarmed at 7 ppm or about that.

    I do not suppose that was a false reading. I did not open any windows, but I did extinguish most of the candles. (I would never leave them burning when I was asleep.)
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