Whether closing a damper increases heat depends entirely on the type of damper you are referring to: a fireplace damper or an HVAC duct damper.
You can adjust the damper slightly while the fire's burning to control the burn rate. A fully open damper allows maximum airflow, making the fire burn hotter and faster. If you want a slower burn or a fire that lasts longer, you can partially close the damper to reduce the oxygen supply.
If you have a two-story home, upper-level dampers should be open during summer and closed during winter. Opening dampers during the summer months distributes cool air evenly to the upper levels. In winter, closing the dampers allows heat to rise naturally, distributing warmer air throughout the upstairs.
When Not in Use. If your log burner isn't in use, close the damper completely to stop cold draughts from sneaking in. But be mindful—if your chimney is prone to dampness, leaving it slightly ajar in mild weather can help prevent moisture build-up inside the flue.
Because your home's HVAC system is designed to regulate the temperature of the entire house, when ducts are closed, this pressure can build up and may eventually cause damage to your ducts or heating system. To sum it up, closing your air vents may mean that: Your HVAC system must work harder.
A fully or partially closed damper pushes back against the air being forced through the system by the blower fan. It increases air resistance inside your ductwork.
Fully open the damper to maximize airflow. It provides ample oxygen to the fire, resulting in a more intense and hotter burn. The damper must be fully open when lighting the fire. It is also the ideal position for quickly warming a cold room.
The Worst Woods to Burn
Spruce and Fir: These softwoods ignite quickly but burn out fast, producing more smoke and soot than hardwoods. They're better reserved for kindling. Green or Freshly Cut Wood: Wood that hasn't been seasoned (dried for at least 6–12 months) contains too much moisture.
The Air Intake of Your Wood Stove
Depending how you stack the firewood greatly affects the burn rate. Keeping the embers close to the airflow with the logs spaced about an inch apart makes for a hot burning, shorter fire. This type of fire is great for heating the stovetop for cooking.
In general, keep the damper open in rooms or zones you want to heat or cool. During summer, open dampers on upper floors to allow cool air to circulate. In the winter, open lower-level dampers to push warm air up. A closed damper restricts airflow to that area, which can be useful for saving energy in unused rooms.
On average, furnaces should kick on and turn off anywhere from three to eight times per hour. However, if your furnace turns on and off more frequently, don't assume the furnace is short cycling just yet.
Additionally, in the early 1980's, tests were conducted to discover which kind of wood created the most creosote in a regular “open” fireplace. The results were surprising. Contrary to popular opinion, the hardwood's, like oak and poplar, created more creosote than the softwoods, like tamarack and pine.
HVAC Damper Open Or Closed In Summer/Winter
In most homes, dampers going to the upstairs are open in the summer and closed in the winter. By closing the dampers to the upstairs in the winter, it allows for the heat to rise naturally after first being introduced into the lower levels of the home.
The biggest mistake? Using logs that simply aren't dry enough. Firewood with high moisture content produces more smoke, less heat and leaves behind sticky tar (creosote) in your flue and burner. It also makes lighting your fire harder, wastes energy and can even damage your stove.
However, if you have a smaller fire pit (less than 3 feet in diameter), you may only need 2-3 logs per hour. Conversely, for larger fire pits (over 4 feet in diameter) or if you're aiming for a roaring fire, you might need 5-6 logs per hour.
Properly cured, or "seasoned" firewood needs to be cut, split and stacked for a minimum of six months to be properly dried for this fall and winters fireplace needs.
Burning wet wood has two negative consequences:
Your fire will smoke more, causing creosote build up in your stove and chimney. Your wood will burn less efficiently, costing you more to create the same amount of heat.
Firewood can be classified as either hardwood or softwood. Hardwoods are denser and stronger than softwoods, making hardwood the preferable choice. They also generally contain less resin, resulting in cleaner fires.
The 3-2-10 rule lays the foundation
The chimney needs to extend at least 3 feet above the roof on the side of the chimney where the roof is highest. The top of the chimney must be at least 2 feet higher than any part of the roof or any component on the roof that's within 10 feet of it.
Poisonous Wood
Burning poison oak, poison ivy, poison sumac, Brazilian peppertree and poisonwood creates smoke with irritant oils that can cause severe breathing problems and eye irritation. “If it's got the word poison in it, I wouldn't be burning it, or eating it or anything else,” says Hammer.
When and Why You Should Open or Close the Flue
It's better to have a damper and not need it than to need one and not have it. A good airtight stove really doesn't need one. You can control the burn adequately with the air inlets. Damping it down in the stack only risks having smoke and fumes coming into the room.
After all, a barometric draft control works by adding air to the flue and leaks in a venting system will have a similar creosote-reducing effect.