However, increasing the flue to a size larger than the stove’s collar (or flue flange) is sometimes permitted. A larger chimney does have a negative effect on draft, since it allows the flue gases to slow and cool before they escape the top of the chimney.

The most common of these being the 2 foot, 10 foot, 3-foot rule. Roughly this means that a chimney should be 3 feet higher than the point it passes through a roof, while also being at least 2 feet taller than any part of a building that’s within 10 feet of the chimney.

The chimney should extend at least 3 feet above the roof surface it penetrates and 2 feet higher than any roofline or other obstacle within a horizontal distance of 10 feet. Taller chimneys make more draft, but chimneys exposed to outside cold don’t. See our section on chimneys.

As a general rule, the diameter of the chimney should match the flue collar on your wood stove. A 6-inch stove requires a 6-inch flue. In most cases, a step up is also fine. For example, you could vent a 6-inch stove into an insulated chimney that is 8 inches in diameter.

Chimney needs to be cleaned: Creosote build up in the chimney can reduce the the flow of exhaust gasses which can cause fireplace smoke and may also lead to a chimney fire. A shattered chimney flue can also cause drafting problems. Such a fire simply can’t generate sufficient heat to allow the chimney to draw well.

Occasional puffs of smoke that enter the room from beneath the chimney breast are usually caused by downdrafts, or air rushing down the chimney in spite of the upward air flow caused by fireplace heat. Downdrafts often occur in windy weather.

A properly sized chimney cap should not interfere with draft. Draft is that which controls how well smoke is drawn up and out of your chimney. The lid of the cap should be at least 5” above the top of the any flue tiles it is covering. Having more clearance than 5” is a good idea.

Without a chimney cap in place, all manner of debris can build up in your chimney. With the risk of the flue becoming blocked, leading to smoke and carbon monoxide back drafting into the home. Or When you light your first fire of the season, that debris can go up in flames and wind up catching your house on fire.

The answer is yes, chimney caps are necessary because manufacturers of relining materials do require them as part of a complete installation. Not installing a chimney cap will void any warranty you have on the pipe.

Widely considered the best type of chimney cap material, stainless steel chimney caps balance cost and performance. Although stainless steel caps are more expensive than aluminum or galvanized steel, they are more durable and require very little maintenance.

Running the fireplace on high for instance with a $0.13 kilowatt hour cost, at 1500 watts will run you about $23.40 a month. However if you run that same fireplace electric heater on a low heat setting it costs only $7.80 a month to run, which is a significant difference.