Carbon Monoxide (CO) is an odorless, colorless gas that results from incomplete combustion. CO is a natural by-product of gas combustion and a certain measure of CO will be produced by all gas burning appliances. In general, readings of 25 to 35 ppm, averaged for the area and time, are acceptable limits. High levels of CO can be harmful or deadly, as CO replaces oxygen in the bloodstream and can result in a condition called hypoxia, where the body is deprived of needed oxygen. A CO detector reading warrants looking at all of the factors involved, which include the gas log set; the environment in which the gas log set operates; the CO detector; and other sources of CO in and around the house.

Attached are troubleshooting information for you to explore. There is quite a bit of items to consider because there is no single cause.

Several things for you to look at and consider:

• Inspect the air intakes around the burner air shutters. If they have become clogged with lint or dust it can negatively impact combustion performance.
• Ensure that there are no gas leaks. Raw natural gas or propane will result in high CO readings.
• We had cases where the cause of the CO alarm going off was the mantle overheating and cooking off the varnish.
• Please ensure that the installation instructions have been followed, especially with regard to the cleanliness of the firebox, the size of the firebox, the placement of the logs and the installation of the glowing embers (small, loose pieces).

The national unvented heater standard (ANSI Z21.11.2) to which all Chillbusters are certified, has the strictest limits for Carbon Monoxide (CO) of all gas burning appliances. The CO limit for a gas burning kitchen range (also an unvented appliance) allows four times the CO permitted for an unvented heater. The ANSI standard allows up to 25 ppm of CO to be present in the combustion gases of an unvented heater.

Carbon monoxide will be present in all types of burning. A person inhales 2000-6000 ppm of CO with each puff of a cigarette. I have measured candles giving off up to 25 ppm of CO. Government guidelines allow up to 35 ppm exposure in an eight hour period.

New CO detectors may needs a seven day warm-up period before reading will have any accuracy. They can be unduly influenced by vapors from petroleum, alcohols, household aerosols or increased indoor humidity (of which a vent-free gas log set contributes one quart of water every hour when burned at 40,000 BTU/hour).

The most common cause of elevated CO readings in a house is due to automobile exhaust from attached garages. The second most is cigarette and cigar smoking indoors.