Sweeping and Repairing Murray's Valley-Floor Chimneys

Burning inside the inversion

When cold air pools down on the valley floor under a warmer layer above it, the pressure difference that normally lifts smoke out of a chimney weakens. Fires take longer to establish, run cooler and smolder instead of burning cleanly. A smoldering fire puts several times more unburned material into a flue than a hot one does, which means a hearth used casually through a long inversion week can build up more deposit than one on the bench that was burned hard. It is one of the few situations where how the weather sat matters more than how many fires you actually lit.

Post-war fireboxes

A large part of this city was built in the two decades after the war, and those fireboxes have now been heated and cooled several thousand times. Firebrick shrinks away from its mortar, the joints in the back corners open up, and dampers warp until they no longer seat properly. None of that is dramatic and none of it happens overnight, but a gap in a firebox wall is a direct path to the framing behind it, which is why we look at the back corners first on a house of that age.

Chases on the newer streets

The building that filled in during the nineties and the two-thousands used factory-built fireboxes vented through a framed and sided chase. Those do not crumble the way brick does. They rust. The chase cover is a sheet of metal, and if it was made from thin stock and left flat it ponds water, corrodes through and drips down the outside of the flue pipe into the cavity. From the yard nothing looks wrong. From the roof you can see it in about ten seconds.

We are licensed and insured and we work on both kinds. Whichever one you have, the visit finishes with photographs of what we actually found up there.