Many homes have a fireplace on a main or upper level of the house along with a fireplace in the basement. Multiple fireplaces are an excellent feature for keeping the entire home warm during the winter. It is also perfect for zone heating allowing homeowners to reduce energy costs by not wasting energy heating empty rooms. However, you should watch out for these three common basement fireplace problems.
A common problem is feeling a cold draft in the basement when the fireplace is not being used. It often occurs on colder windy days due to the stack effect. The stack effect is the movement of oxygen in and out of the chimney stack. Both the fireplace and chimney use indoor oxygen for the draft. As the warm air (high pressure) rises and exits the chimney, it is replaced by cold air (low pressure) entering the basement fireplace. The point in the home where both the high-pressure air and low-pressure air meet is called the neutral plane. The area of the house above the neutral plane is high pressure or warmer air, while below the neutral plane, like the basement, is the cooler low-pressure air.
On a particularly windy day, wind gusts can also force cold outside air down the flue where it will exit the fireplace in the basement. Closing the damper can help minimize downdrafts, but if the damper is warped, damaged, or has a broken seal, you may still experience a cold draft. Another option is to install a top-sealing damper. It seals the flue from the top of the chimney preventing cold air from going down the flue when the basement fireplace is not being used.
Another problem is smelling smoke in the basement when using an upstairs fireplace. Even though the basement fireplace and the upper fireplace have separate flues, they are both housed in the same chimney chase. Depending on which way the wind is blowing, when the smoke exits the second flue, it may cross over the first flue. Cross over smoke can also occur when there are cracks or other damage to the flue liner. Also, if you have an older masonry chimney, there may be cracks in the bricks, gaps in the mortar joints, or chimney crown cracks that can be air pockets. Make sure to have an annual chimney inspection and make the recommended repairs timely. Ask your chimney sweep to conduct a video scan of the flue to check for any signs of damage. A video flue scan can find small issues that a visual inspection may not spot.
The air moving in and out of the chimney can stir up dust, soot, creosote, and debris in the flue. Moisture and humidity can promote the growth of bacteria and fungus, contributing to the pungent aroma. There may also be remnants of small animals, birds, and pests. Scheduling an appointment with a professional chimney sweep to clean the chimney will eradicate the foul odor. Homeowners should have annual chimney cleanings, but more frequent fireplace use may require more frequent sweeping. Also, it is not uncommon to find leaves, twigs, and small animals blocking the flue vent. A flue obstruction can impede the expelling of smoke and fumes, causing them to back-up into your basement or upstairs living space.