Silent killer
Numerous cases of chimney-liner problems every year in city

Darrell Greer
Northern News Services

NNSL (Sep 09/98) - This is the time of year Yellowknife homeowners can take precautionary steps to avoid having tragedy strike their families this winter, said deputy fire Chief Mike Lowing.

Newer model fuel burning home-heating systems have a tendency to run into chimney problems once the Yellowknife winter kicks into full drive and temperatures begin to plummet.

"What we find with these furnaces is that when they're running, the temperature inside the chimney, what we call the stack temperature, doesn't really get hot enough and you run into problems with water vapour," said Lowing.

The problem wasn't as prevalent in days gone by because old furnaces would burn hotter or, because the homes weren't as energy efficient, would burn longer.

As a result, the stack temperature would allow products of combustion, which includes water vapour from diesel oil, to clear the chimney.

With newer home-heating systems, once the temperature sinks to -40 C, instead of escaping the chimney, water vapour can actually collect on the top.

"You'll see big chunks of ice hanging off the chimneys all over town on the newer homes," said Lowing.

"This isn't a hazard in itself, but it's an indication you have water vapour that's not escaping."

In some situations, the water vapour, as it goes up, cools off, condenses and starts to work its way down the inner liner of the chimney.

Lowing said it's always a good idea, before the really cold weather hits, for people to get their home- heating systems serviced, not only for safety, but also for fuel economy.

During that process, home owners can take the opportunity to have their liners inspected.

Lowing said the liners don't collapse overnight, often taking a number of months, or years in some cases, to collapse.

He cautions, however, although some liners may take a decade to collapse, others can collapse very quickly.

"If a person has a routine inspection of their fuel-fired appliance done by a qualified person, they can see the problem very quickly because when you look up against the skylight, it should be a round circular opening right to the top.

"If you get warbles, dents, wheezes, anything in the chimney, it tells you that your liner is separating."

A collapsing liner can mean a major carbon monoxide problem.

As the liner collapses, it could occlude and force the carbon monoxide back into the home from the fuel exhaust.

There is also the danger that as the collapse works its way below the roof line, the chimney may loose its integrity and allow products of combustion to enter back into the roof space, which then enter back into the home.

"We see lots of chimney-liner failures every year in the city," said Lowing.

"The main focus in catching it is that it is a life-saving issue."

For more information, contact the Yellowknife fire department or city hall.