Mother's Flue Alarm

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This device will warn you should a chimney fire occur.

Chimney fires are of almost constant concern to everyone who heats with wood. The residues of incomplete combustion that are produced in most woodstoves can form heavy deposits that sometimes ignite to create chimney- (or home-) destroying infernos. On page 114 of this issue, scientists Jay Shelton and Cathleen Barczys discuss the research they're now doing (in cooperation with MOTHER) in order to evaluate several devices which are claimed to reduce creosote formation. Ultimately, woodstoves will have to become safer, cleaner, and more efficient if they're to maintain their popularity in an environmentally concerned world. But, in the meantime, it's up to the individual owner to operate his or her stove in the safest manner possible.

At least one smoke alarm and fire extinguisher should be strategically located in every home that has a woodstove. (In fact, such devices can be lifesavers in any dwelling, regardless of how it's heated.) A smoke detector can provide an early-warning even before an actual blaze gets started, and—by doing so—helps to protect the building's occupants from the number one fire danger . . . smoke inhalation.

What's more, woodstove owners can employ other potentially lifesaving devices. Several companies now market alarms that signal the overheating of a woodburning appliance's flue . . . giving an early warning of the onset of a chimney fire. The commercial units run up to nearly $80 (although some are a good bit less expensive), but any handyperson who enjoys tinkering (and, perhaps, saving a few dollars at the same time) will find that building a flue alarm can be an easy, enjoyable project.

MOTHER researcher Emerson Smyers put together the device you see in the accompanying photo and illustration, using readily available components, for under $25. The alarm is self-contained (its power is drawn from a 9-volt battery) and signals overheating with a loud buzz. We purchased the thermometer portion of it from the Condar Company, Dept. TMEN, Box 6, Hiram, Ohio 44234 (for $11.95, plus $1.00 shipping), and all the electronic components were obtained from a nearby Radio Shack outlet.

First, Smyers modified the thermometer by adding a pair of automotive ignition points to the dial. One contact was silver-soldered (regular solder might not stand up to the heat of the flue) to the °F pointer, and the other was attached to an arm (with a small, insulating piece of circuit board between the two components) which pivots under the bolt in the center of the thermometer. The second contact, then, can be set to a specific temperature, and when the first contact touches it, the circuit will be completed . . . triggering the alarm. While all this is going on, of course, Condar's Chimgard still serves its original purpose: allowing you to monitor flue temperature easily.