Chimney Sweeping in Whitefish, MT

Why less use produces worse deposits

The intuition is that a fireplace used a dozen times a season needs less attention than one used nightly. In a large stone chimney the opposite holds, and the mechanism is thermal mass. All that masonry has to come up to temperature before the flue stops condensing, and from a cold start that takes a long time. In a house heated continuously the mass stays warm and the flue runs dry. In a house fired from cold every few weeks, every single fire spends a long stretch below the condensation threshold.

What that leaves behind is the sticky second-stage creosote, which is the kind that sustains a chimney fire, rather than the light flaky deposit a hot steady burn produces. Rental properties are worse again, because the person lighting the fire is not the person who will be here tomorrow and frequently damps it down for the night.