What to Measure Before You Shop for Gas Logs

A gas log set is not one size. The burner has to sit inside the firebox with room around it, the logs have to clear the sides, and on a vented set the flame needs somewhere to go. Get the opening wrong by two inches and the set either does not fit or it looks wrong forever.

So before you shop, get on the floor with a tape measure. Here is what we need.

The four measurements

Measure the opening of the firebox, not the mantel and not the stone surround. The opening is the hole the fire goes in.

Take the width twice. Fireboxes are usually narrower at the back than the front, sometimes by six inches or more, and the back width is what decides how wide a set can physically sit.

• Front width. Left to right, across the very front of the opening.
• Back width. Left to right, across the back wall of the firebox.
• Depth. Front edge straight back to the back wall.
• Height. Floor of the firebox up to the top of the opening.

Then take one photo

While you are down there, take a picture of the opening square on, and a second one of the whole fireplace including the surround and the mantel.

The photo tells us things the numbers do not: whether the firebox is masonry or a metal prefab, whether there is a damper and what shape it is in, whether there is already a gas line coming through the floor or the side wall, and what the room around it looks like. All four change what we would put in there.

Why the back width catches people out

A set that fits the front of your fireplace can still be too wide at the back. The grate has to sit flat and the logs have to sit on the grate without touching the side walls, so on a steeply tapered firebox the back measurement, not the front one, is the limit.

This is the single most common reason a set bought online goes back in the box. Nobody measures the back.

Do you need a gas line already?

Not to shop. You do need one before anything gets installed, and if there is not one there now that is a normal thing to sort out rather than a dealbreaker.

Tell us what you have and we will tell you what running a line to that fireplace usually involves, before you spend anything.

Then come and watch them burn

Once we know the opening, the rest is a decision you cannot make from a photograph. We keep more than twenty different sets plumbed and lit on the floor, because flame height, flame movement and how the embers glow are the whole point of a gas log set and none of them survive being photographed.

Bring the four numbers and the photo. We will tell you honestly what fits, what does not, and what we would put in your room.