How do I Stop Cold Air From Leaking in a Majestic Gas Fireplace?

Written by gwen chance
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How do I Stop Cold Air From Leaking in a Majestic Gas Fireplace?
A gas fireplace can heat a room quickly. (fireplace image by Ekaterina Sidorenko from

As beautiful and romantic as they are, fireplaces are not energy efficient. Unused, they can rob heat from a room. Gas fireplaces are an improvement over wood-burning ones but when they aren't in use they can still be draughty. Blocking the draft depends on how often you use the fireplace and how many decorating and style compromises you're willing to make. Some methods for stopping the cold draft are dangerous if you forget to undo them before using the fireplace.

Skill level:

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Things you need

  • Building materials that match home
  • Fabric
  • Insulation
  • Blanket
  • Screen

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    Finding and Blocking the Draft

  1. 1

    Understand what you have. Gas fireplaces have a firebox you see from your room. It usually has a false brick backing and fake logs. The firebox is wrapped by a second metal box to form an air space between. Depending on your design, the air cavity may open into your room and you may have a circulating fan that blows heated air out into your room. In turn, the fireplace is built into your house. It sits surrounded by air in an empty chase sized to manufacturer specifications. This second air space keeps the hot metal away from combustible materials --- the rest of your house.

    How do I Stop Cold Air From Leaking in a Majestic Gas Fireplace?
    Flames can be mesmerising. (fireplace image by Michael Shake from
  2. 2

    Close the fireplace vent. If you have a vented fireplace, the largest draft source is the vent. Vents exhaust combustion gasses to the outside. Keep the vent damper (a hinged door) closed when you're not using the fireplace. However, some states require the damper to be welded open. The states want to make sure you do not kill your family by carbon monoxide poisoning. If you stuff the vent with fabric or insulation be sure to unblock it when you start a fire. Unvented units do not have a damper. The firebox is closed without direct access to outdoor air.

  3. 3

    Close the doors. Vented units may come with glass doors. Closing the doors when the fireplace is not in use will lessen drafts.

    Unvented gas fireplaces do not have glass doors. Unvented units burn at high heat levels to burn off poisonous gases. That heat also damages glass doors.

  4. 4

    Check and repair the outside chase. Look for holes and gaps open to the outdoors. Fill with materials that match the existing decor, keeping in mind your local building codes for combustibility and manufacturer's recommendations. Remember to look up underneath your fireplace if your chase doesn't go down to ground level. Animals may have chewed through materials and into the cavity, letting cold outside air get closer to your room.

  5. 5

    Block the air cavity openings when the fireplace is not in use. Block the drafts with solid screens or hanging blankets but remember that these can catch fire if you don't remove them before turning on the gas. The tighter the seal between the screen or blanket and the fireplace front, the less the draft.

    If you don't use your fireplace, consider sealing it off with clear plastic film systems recommended for insulating windows.

Tips and warnings

  • The only 100 per cent effective method to block drafts is to remove the fireplace and wall off the cavity.
  • For your safety, remember to remove all draft blocking items when you turn your fireplace on.
  • Keep blocking items away from pilot. If blocking, turn off gas to the pilot to prevent accidentally snuffing or fire.
  • Fire is dangerous. Keep flammable objects away from open flames and install smoke detectors in your home.
  • Install carbon monoxide detectors to warn when invisible gases are reaching the danger level. Early symptoms of carbon monoxide poisoning are head and body aches.
  • Some locations ban unvented gas fireplaces.

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