The Contour is an older model, but doesn't mean that it has CSS. Also, the Combustion blower should be removed at least once a yr (the area you need to clean) according to the manual As for CSS, some older Quads (Contour, 800, 1000, etc) did start up in the heat level selected (opposed to the New Quads starting in High, regardless of heat setting). But that Does Not mean that the older units wont start on Low or Medium All the new Heatilators run just like the Older Quads. They start up in the heat setting they are on, just as the old box stoves. They start fine as does any other stove that is clean, has a good ignitor, clean vent, maintained motors and.blowers, and feed rate set correctly. CSS is a made up term, related to this site only.