Lighting the fireplace on a cold afternoon is one of winter’s greatest pleasures—the crackling of the wood, the enveloping warmth, the cozy atmosphere… But all that comfort can be ruined if the chimney draft isn’t properly regulated.
Open or closed chimney draft? This is one of the most common questions among fireplace users, especially when starting, maintaining, or extinguishing the fire. Regulating the draft not only affects the amount of heat you get, but also impacts safety, wood consumption, and maintenance.
In this guide, we explain everything you need to know to use your fireplace efficiently and safely. We include quick-start instructions for beginners, technical tips for advanced users, and clear answers to the most common questions.
What is the chimney draft and why is it so important?
The draft is the flow of air that rises through the flue and expels the gases produced by combustion. It’s created by the pressure difference between the hot air inside and the colder air outside.
A well-regulated draft ensures:
- 🔥 Better combustion
- 🌱 Lower wood consumption
- 🛑 Less smoke inside the home
- ✅ Safer operation
The ideal draft pressure for most modern fireplaces ranges between 11 and 13 pascals (Pa).
Quick Reference Table: Open or Closed Draft by Phase
| Phase | Draft | Door | Main goal |
|---|---|---|---|
| 🔥 Ignition | Open | Open | Help smoke escape and activate the draft |
| 🔥 Active combustion | Partially open | Closed or slightly open | Control the fire and retain heat |
| 🔥🔥 Ember/burn-out phase | Closed | Closed | Preserve heat and prevent cold air from entering |
Phase: 🔥 Ignition
Draft: Open
Door: Open
Main goal: Help smoke escape and activate the draft
Phase: 🔥 Active combustion
Draft: Partially open
Door: Closed or slightly open
Main goal: Control the fire and retain heat
Phase: 🔥🔥 Ember/burn-out phase
Draft: Closed
Door: Closed
Main goal: Preserve heat and prevent cold air from entering
Practical Instructions: How to Adjust the Chimney Draft Step by Step
Phase 1: Ignition
- Fully open the draft.
- If your fireplace allows it, keep the door open.
- Use dry wood and natural fire starters.
- Wait 30 to 40 minutes until the draft is fully active and the fire is stable.
Phase 2: Active Combustion
- Gradually reduce the draft, but never close it completely while there’s still flame.
- Close the door to maintain temperature and prevent smoke leaks.
- Watch the flame: it should be lively, stable, and show bluish or controlled yellow tones.
Phase 3: Burn-out / Embers
- Once only embers remain, you can fully close the draft.
- This preserves heat and prevents warm air from escaping through the flue.
- Also close the door for maximum efficiency.
Difference Between Open and Closed Fireplaces
- Open fireplace: More decorative than efficient. Up to 80% of the heat is lost through the flue. Hard to control and more polluting.
- Closed fireplace (cassette or insert): Higher thermal efficiency, better draft control, and safer. Ideal for regular use or as auxiliary heating.
Technical Draft Regulation: For Advanced Users
Types of Air Inlets
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Primary air: Enters from the bottom. Used to initiate combustion.
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Secondary air: Enters from the top. Enhances combustion, reduces residue, and helps keep the glass clean.
Double Combustion System
Some modern fireplaces feature a system that reuses unburned gases, burning them with secondary air. This:
-
Reduces harmful emissions
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Increases energy efficiency
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Minimizes soot and creosote buildup
Automatic Devices
There are automatic draft regulators that adjust the opening based on temperature or pressure levels. These are ideal for:
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Areas with strong winds or varying altitudes
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Users seeking efficiency without manual adjustments
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Homes with daily fireplace use
Frequently Asked Questions
Should I fully close the draft when turning off the fireplace?
Yes. Once there are no active flames or embers, closing the draft helps retain heat and prevents cold air from entering.
Is it dangerous to close the draft while there’s still fire?
Very dangerous. It can lead to a buildup of toxic gases (like carbon monoxide) and cause smoke to back up into the room. Keep the draft open as long as there is active fire.
Can I leave the door open while the fire is burning?
Only during ignition or if your model is designed as an open fireplace. In closed models, keeping the door shut improves both safety and efficiency.
Extra Tips for an Efficient Draft
- 🧹 Schedule annual chimney cleanings to avoid blockages (soot, nests).
- 🌬 Install a draft stabilizer if you live in a windy or high-altitude area.
- 🌲 Always use dry, seasoned wood to reduce smoke and improve combustion.
- 🛑 Install a carbon monoxide detector near the fireplace for added safety.
Conclusion
The answer to “open or closed chimney draft?” depends on the phase of the fire and the type of fireplace you’re using. The key is to watch the fire, adjust gradually, and never close the draft while flames are still burning.
With proper draft regulation, you’ll enjoy:
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Greater thermal comfort
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Lower wood consumption
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Increased safety for your home
Enjoy your fireplace smartly, warmly, and safely.
