kwired has the right idea. Beyond what he said check the entire package for a UL, FM or other NRTL mark. In general, you should find it on or very near the ignitor and it should (very) briefly describe the system it is certifying. If it is so marked, you're home free; if not, check with your local fire marshall.
Gas furnaces, water heaters, clothes washers & dryers etc. fall pretty much under the same concepts. Small gas users, especially where the gas is odorized and the equipment is third-party certified, rarely call for electrical classified location techniques. Other cautions that may come with the equipment should be observed, of course.