Q I have an old house with a fireplace built to burn coal. Can I use charcoal briquettes? Are homes heated with coal anymore, or has it been outlawed? Are there any companies that deliver coal anymore?

A It hasn't been outlawed, but burning coal in the fireplace certainly is not a good idea, said energy specialist Phil Smith with the Minnesota Office of Energy Security.

Coal is dirty -- in the house and in the air. For the same reason, you don't want to use charcoal briquettes. In addition, they produce a lot of carbon monoxide, posing a health hazard in your home.

You'll have a hard time finding the right kind of coal to burn, Smith said. Very hard coal, anthracite or bituminous, is what you'd need. Power plants burn coal, but in Minnesota, it's western low-sulfur coal. You could scour the railroad lines near them to pick up any cast coal. But this coal would not burn in your fireplace as you'd expect it to, Smith said.

There are major differences between wood- and coal-burning fireplaces. Coal burns very hot, so fireplace openings are small; the hearth iron and the grates also are different than for wood-burning. If you do acquire some coal, be sure you actually have a coal-burning fireplace and that the flue is in tip-top shape.

The better choice is to leave the fireplace dark. Another option, Smith says, would be to convert it to use gas. A sealed gas fireplace is the best choice from the standpoints of air quality, efficiency and safety.

Save old elm?

Q We have a huge, mature elm tree in our back yard that is healthy. I was told that Dutch elm disease spreads best either root to root or by touching branches with an infected tree. There are no nearby elms. Should we begin fungicide treatment of the tree as a preventive measure?

A Although Dutch elm disease can spread via roots or branches, that's not the most common way it's spread, said Mark Stennes, plant pathologist and Dutch elm expert. The biggest culprit is the Dutch elm beetle that goes from tree to tree.

You'll have to decide for yourself if the tree is worth trying to save. Fungicide treatments involve injecting the tree roots just under the ground every three years, and it's very effective, Stennes said. The two products out there both work, he said, but propiconazole costs less and is less hard on the tree.

In any case, it's important to realize that it's not always 100 percent effective.

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