Why would you close a damper?

Author: Mona Von  |  Last update: Sunday, March 23, 2025

1. In the summer, a closed damper helps to keep cool, air-conditioned air inside the home where it belongs. 2. In the winter, when you're not using the fireplace, a closed damper helps to keep cold air from swirling down into the house.

When should you close a damper?

The damper is designed to be shut when the fireplace is not in use and can be easily opened when it is. It's common to forget to close the damper after a fire goes out, however, and that leaves a big hole through which heated or cooled air can escape the house.

What does closing damper do?

When dampers are open, they allow airflow unimpeded. When closed, they restrict airflow. Thus, HVAC dampers play a role in regulating interior temperatures as they control the flow of hot and cool air to the various rooms of your house. HVAC dampers are usually inside your ducts, close to the main air handler.

Is it OK to leave damper open?

One common myth about chimneys is that leaving the damper open during the summer helps “air out” the chimney. However, the opposite of true. Leaving the damper open just fouls up the rest of your home, and does nothing to clean your chimney.

Do you get more heat with a damper open or closed?

Yes, if you close your damper you will get more heat build up. Enough to possibly burn your house down or spill smoke and carbon monoxide into the home. Don't do it! Your fireplace was tested and listed with the damper wide open.

How to Use a Damper on a Wood Stove

What happens if damper is closed?

A closed throat damper will cause smoke to fill your house immediately when you start a fire. If you have a chimney with a closed top-mount damper It might take a few minutes for smoke to start filling the house, but you will eventually notice that there isn't enough airflow.

What position should my damper be in?

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.

Should fireplace damper be open in summer?

In the summer, a closed damper helps to keep cool, air-conditioned air inside the home where it belongs. 2. In the winter, when you're not using the fireplace, a closed damper helps to keep cold air from swirling down into the house.

How much heat is lost through an open chimney?

Warm air from your home naturally rises, and an open chimney provides an easy escape route. In fact, it's estimated that up to 30% of your home's heated air can be lost through an open chimney when the fire isn't in use.

How should damper be in summer?

In the summer, it's critical to open the dampers on the upper level and block as much air from entering the basement as possible. If you have someone to assist you, one simple method to see whether the dampers are open or closed is to have someone go up and cover each vent with their hand.

What is the main function of a damper?

A damper is a valve or plate that stops or regulates the flow of air inside a duct, chimney, VAV box, air handler, or other air-handling equipment.

Does closing a damper increase heat?

By not creating an airtight seal, these dampers minimize the strain on the system. In summer, you can close the dampers downstairs so cooler air reaches upstairs rooms. But in winter, closing upstairs vents halfway allows heat to rise.

Should damper be fully open?

A closed damper also stops cold drafts from coming down the chimney. When you are using your fireplace, it needs to be open so that smoke can vent outside. It also allows fresh air to come in to feed the fire.

Can you close a damper all the way?

The damper is the part inside your flue that controls the airflow entering and exiting the tunnel. Should you close a damper all the way? Always fully close the damper when you are not using the fireplace. This will lower your energy bills and prevent leaf litter or pesky critters from invading your home.

Can you go to bed with embers in the fireplace?

No, you should never leave a fireplace burning overnight or unattended during the day.

What is the difference between a flue and a damper?

The damper and flue are two different parts, but they are related and involved in the same function. The flue is the inside tunnel of your chimney that brings gases from your fireplace out of your home, while the damper closes or opens the access to the flue.

What temperature do chimney fires start?

According to the Chimney Safety Institute of America, Creosote can ignite at temperatures as low as 451 degrees F (for context, a fire in your fireplace can burn in excess of 450 degrees F), and even just a 1/8” buildup of creosote is considered high enough to cause a chimney fire.

Is it bad to leave your chimney flue open?

It's best to keep the flue closed when the fireplace is not in use. Should it stay open for too long cold air, debris, rain, and even animals can make their way inside your home.

Can you block an unused chimney?

As one of the biggest causes of a draughty home, it can make sense to block a chimney opening, especially for larger unused fireplaces. Fixing a draughty chimney not only makes your home more comfortable, it helps to lower energy costs too.

Does closing damper make fire hotter?

To create fires that produce more heat, open the damper as wide as possible when lighting a fire. A wide-open damper will increase the amount of air reaching the fire and improve combustion. As a result, the fire will burn hotter.

What happens if fireplace damper is closed?

The damper to your fireplace must be completely open when a fire is burning. If you close the damper even slightly, you risk allowing smoke and other dangerous contaminants from the combustion process into the house. And remember, the most dangerous by-product of combustion is carbon monoxide.

Can I use my fireplace without a damper?

Whether your fireplace is gas or wood-burning, if it was built with a pre-fabricated insert, then it almost certainly has a damper. And while older wood-burning fireplaces can function safely without a damper (gas fireplaces cannot), a chimney without a damper is just a gaping hole in the roof of your house.

Why would a damper be closed?

It connects to a lever that rotates to redirect airflow throughout your ductwork. For example, opening a damper allows the temperature-controlled air from your furnace or air conditioner to flow through that area of your duct system, while closing it restricts that airflow.

When should you close your damper?

If you're burning wood, keep it fully open until all the burning embers are completely burned out. If it's a gas log set, turn off the flames before the closing the damper as far as possible. If there is no fire, always keep the damper closed to prevent air infiltration and heat from being lost up the chimney.

How do I know if my damper is bad?

Put the damper into an open position and check the registers once again to see if the airflow starts. If the damper is closed and you are feeling low airflow, or none at all, it is most likely a bad damper.

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