Vent-free fireplaces.

Q: Are vent-free fireplaces really a good idea?

A: Vent-free (better described as "house-vented") fireplaces are one of the most misunderstood appliances in today's home building/remodeling industry. Somehow, the manufacturers of these appliances have been able to con the general public into believing that installing these things is actually a smart thing to do. They have heavily focused their marketing around the fact that they are 99 percent efficient. While this is true, it doesn't make it a good idea. An un-vented wood-burning fireplace would be efficient too ... but we don't see too many of those being installed!

When combustion of a fuel takes place, there are a variety of health-affecting by-products produced, including nitrogen oxides, carbon monoxide, carbon dioxide, aldehydes, sulphur dioxide, particulates, and water vapor. While most people don't consider water vapor to be harmful, it does in fact lead to increased levels of condensation and mold growth if not properly managed. One gallon of water is released into the home for every 100,000 btu's of gas burned. That's a lot!

Sharing your breathing-air with these by-products of combustion can lead to a variety of consequences. Headaches and nausea are frequently reported symptoms, and in some cases, carbon monoxide poisoning has lead to death. The most common health effects are chronic, low-grade, hard-to-define ailments and health deterioration due to long-term exposure to the combustion gases.

If you read the operating manuals of these "vent-free" fireplaces carefully, you will notice that all of them suggest opening a window while operating. Why do you think that is? Why in the world would you need to dilute your home with fresh air when you turn on the fireplace? Do you think there's a possibility that it is polluting your air? You bet!

So, if you're going to install a fireplace (gas or otherwise), it is very important that this device be vented to the outside, and preferably have its combustion air delivered to it from the outside as well. The best scenario is when,the combustion air is separated from the breathing air--referred to as "sealed combustion." This is the safest form of combustion appliance (fireplace, furnace, or water heater).

If you don't have the luxury of purchasing the safest fireplace on the market, there are a few things to keep in mind this winter as you try to stay warm. We commonly hear homeowners say that their fireplaces don't draft very well ... or they're smoky ... or they're hard to get started. There are a few things that lead to this phenomenon.

The most common cause of these problems is that the house is competing with the chimney. Yep, that's right. The house is a better chimney than the chimney. Think of it this way: If you took all of the holes in the top of your house (can lights, electrical outlets, duct registers, etc.) and squashed them all together into one big hole ... it may be larger than the hole in your chimney. If this is the case, then the holes in the top of the house will allow the warm air in the home to escape. This, in turn, creates a negative pressure at the bottom of the house, where the fireplace is most likely located, causing your fireplace to work in reverse--sucking air down the chimney and out into the living space, pulling even more combustion byproducts into the living environment. This concept also applies to fuel-burning furnaces and water-heaters that are "atmospherically vented," which means that they require air from the living space to feed the flame, just like the traditional fireplace.

By addressing these air leakage and pressure issues, you not only create a healthier house, you also reduce the amount of energy required to keep the house comfortable. As I'm sure you know, fuel prices aren't going down anytime soon. So, prepare your house for the heating season, make sure your fireplaces are working properly (throw it away if it is a house-vented fireplace), and save some money this winter!

Isaac Savage is president of Home Energy Partners, a Building Performance Contracting firm that is located in Asheville, NC. He can be reached at 828-350-1155 or on the web at www.HomeEnergyPartners.com