As the temperatures drop, many people's thoughts turn to wood crackling in a fireplace.
But homeowners who haven't maintained their chimneys may find that they must change the fuel for their winter traditions.
November 2010 updates to the Palo Alto building codes puts the city of Palo Alto in compliance with Bay Area Air Quality Control Management District requirements aimed at reducing wood-smoke air pollution. The codes prohibit one-for-one replacement of a damaged wood-burning fireplace or the construction of a new one.
"You can't build a new one, but you can keep an existing wood-burning fireplace in operational shape," Larry Perlin, chief building official, said.
Serious deterioration often goes unnoticed or unrepaired until a new homeowner inspects the property, according to local chimney professionals.
"We're still repairing chimneys damaged in the '89 earthquake," John Klein, owner of Redwood City-based Mr. Chimney Cricket, said.
In addition to structural damage from earthquakes, TV antennas, strong winds and cracks caused by exposure to sun and rain, Palo Alto fireplaces often have damaged firebricks in the back wall of the firebox, repairmen said. The bricks settle or deteriorate after being subjected to hot fires and eventually fall apart, leaving regular brick in direct contact with heat.
"Behind those firebricks are regular bricks, which will transfer heat to the wood behind it. It puts the homeowner at risk for house fires," Klein said.
Even a sound fireplace poses dangers for a home if it isn't properly cleaned, so homeowners might lose a lot more than their existing fireplace.
"These fires are 2,000 to 3,000 degrees in temperature and produce creosote, which is highly flammable. As it cools down traveling up the chimney, it goes from smoke to solid and begins to line the chimney. It can light like a match-head," he said.
Those who'd like to keep a safe and legal wood-burning fireplace need to have it regularly maintained.
"My rule of thumb is that after two years of heavy use without cleaning, you should have your chimney cleaned and inspected," he said.
In his 35 years in the field, Klein said that he hasn't often found serious damage during routine cleanings. Many chimneys only need a cleaning or minor repairs to maintain safe operation. During a recent inspection, he unjammed a half-open damper that had been keeping a Palo Alto house heat-inefficient and prone to smoky rooms on the special occasions that call for a warm hearth.
Palo Alto homeowners who in the course of regular maintenance find that their chimney needs repairs need to apply for a city permit.
"If an existing chimney were not up to code, there would be a trigger point: If the repairs being done didn't involve bringing it up to code, then part of the permit would require updating the chimney," Perlin said.
This doesn't mean that any wood-burning fireplace can be maintained indefinitely.
"If the integrity of the chimney structure itself has been compromised, as in if the back wall physically sways or if the chimney rocks at roof level, then repairs aren't a good idea," Klein said.
Homeowners who can't maintain a wood-burning fireplace because of building codes or environmental concerns can resort to other heating options, local fireplace salesmen said.
The traditional alternatives are several varieties of gas fireplace, according to Alan Karcinich, general manager at San Carlos-based Energy House with more than 30 years in the trade.
A gas line that goes to the fireplace is necessary for each, which can be installed by a licensed plumber.
But these can only be done if there is no major structural damage beyond cracking.
A gas log set can reproduce the look but neither the feel nor the warmth of the crackling fires of yesteryear for around $500, Karcinich said.
It consists of ceramic logs set above grate with a gas insert and uses "ember wool" to emulate the look of glowing embers beneath and beside logs, Drew Stancliffe of San Carlos ABA Hearth and Home explained.
"It's decorative heating appliance and is below a certain efficiency rating. Decorative heating appliances use a lot of gas but don't produce much heat," Stancliffe said.
Gas inserts, though much more expensive at around $12,000, have their own liner and flue systems, Stancliffe said. Old cracks in the existing liner would need to be repaired prior to installation, though.
Behind a fixed-glass front, gas-fueled flames go around ceramic logs, stones or glass, producing greater heat then a gas log set provides.
"Gas logs go into an existing fireplace and all that you're doing is changing the type of fuel that it's using," Stancliffe said.
Homeowners seeking gas-alternatives for their heating needs can still legally install EPA wood-burning fireplaces as well as a novel option, alcohol-burning stoves.
These space-heating stoves can be placed in any fireplace, even one with a damaged chimney. As the only byproducts of burning alcohol are water and carbon dioxide, the chimney can be closed off with a filling material.
Darlene McDermont replaced her fireplace with two wood-burning stoves from a Mountain View shop during a green remodel of the Palo Alto home she shares with husband Tom.
She said she enjoys the blue flames, the heat they produce, and the fact that they don't contribute to air pollution.
"They're great space heaters. I don't miss burning wood."
While the idea of replacing a traditional fireplace may alienate traditionalists, no mandatory phase-out is currently in the works, and even local chimney repairmen validate city efforts to comply with environmental regulations.
"Building codes get better when they need to get better, and stronger air standards make the air cleaner for everyone," Klein said.