Keith Hipsher has seen a lot of chimneys in his 30 years as a chimney sweep cleaning and inspecting Midpeninsula fireplaces.
Before you light that match for the first wood fire of the winter season, if you still have a wood-burning fireplace, he says, "start small."
The owner of Chim Chimney cleaning and repair service in Redwood City says also to make sure the damper (the black metal door in the chimney that blocks air from coming in) is wide open..
The way to check and also "prime" the flue, or the passageway that allows the smoke to rise through your chimney, is to roll up some newspaper, light it, and hold it up in the passage to allow the air to warm.
Also, if you haven't had your chimney looked at or cleaned in three years, or you've just bought your home, have it inspected before you light a fire. Hipsher has gotten numerous calls from customers who say they just lit a fire and already within 10 seconds, smoke is billowing into their home. The usual cause, he says, is the damper isn't open all the way.
If you only use your fireplace once or twice a year, it's only necessary to have it cleaned about every three years or so, said Palo Alto Fire Marshal James Henrikson. But if you use your fireplace nearly every day during the winter, a once-yearly cleaning will likely be necessary.
What happens in the intervals between fires (especially if the fireplace is very infrequently used) is spiders or even squirrels can build nests in the chimney inhibiting the flow of smoke.
While in the East Coast they use the damper (the sort of door high up in the flue that's controlled by a handle inside the fireplace) to control how much air flows in, in California, its used to keep cold air out in between fires.
Another thing to watch for is that the spark arrestor on top of the chimney ( a black metal cage-like device) is working properly, Henrikson said. Lightweight floating embers are a leading cause of fires that start outside homes, or even wildfires in the summer, he said. The embers can escape the spark arrestor and land far away from the home. "It's more of an issue with the cardboard and paper you burn," he said, as well as Duraflame log wrappers.
While he hasn't responded to a chimney fire in Palo Alto in about two years, he strongly advises against burning trash. "I would definitely steer your readers away from burning any trash," he said.
As for new homebuyers, "My recommendation would be that any new homeowner has their chimney and flue evaluated," Henrikson said.
As of Nov. 1, the Bay Area Air Quality Management District is enforcing a ban on building new wood-burning fireplaces in the Bay Area. New homes can have only gas inserts or electrical fireplaces. The only wood-burning devices allowed in new construction are EPA-certified wood-burning devices or pellet-fueled ones. Also beginning this month, Bay Area residents who begin a chimney or fireplace remodeling project that costs over $15,000 and requires a building permit will only be allowed to install a gas-fueled, electric or EPA-certified device. In Menlo Park, no existing wood-burning chimney repairs are allowed at all. The new rule does not completely ban fireplaces and wood stoves or completely prohibit wood-burning in the Bay Area, or require the replacement of existing fireplaces or wood stoves when a house is sold.
"We are kind of going away from (wood-burning fireplaces). Most of them are being torn down because they're a seismic hazard and quite often they can be broken or have issues of buildup of creosote that can actually cause fires within the fireplace," said Bud Starmer, the Palo Alto building inspection supervisor.
When inspecting a chimney, Hipsher says that he first looks at the outside of the chimney to check for cracks from small earthquakes or settling. Next he looks at how high the chimney sticks up above the roof to see how smoke will flow out. Inside, he checks the back wall of the fireplace to see how dirty it is. Then he checks the "physics" of the room the fireplace is in to see how much draft the fireplace has. If the home has new windows, generally that means there are no air leaks, which means "the fireplace struggles for air," he said.
If you are going to use your fireplace, generally real wood burns hotter than starter logs like Duraflames and wood burns more cleanly and leaves less creosote on the sides of the chimney, Hipsher said.
If the creosote (the black soot-like substance in the fire box) is betwen 1/8 and a 3/16 of an inch thick, it's likely it needs cleaning.