Grate 18 vs Grate 30 vs Grate 36: Which Size Is Right for Your Space?

A fireplace grate is chosen first by your firebox's internal dimensions, then by the scale of the room it sits in, and last by the flame presence you want it to have. Get the firebox fit right and you have narrowed the field; get the room scale right and you have usually settled the choice; the flame presence decides between the two models that remain. Run the levers in that order and the answer tends to fall out on its own.

Those three levers are worth holding in mind as you read on:

• Firebox fit. Each model needs a minimum opening to sit and operate correctly. This is a pass-or-fail gate, not a preference, so it filters the list before anything else does.

• Room and space scale. A grate that fits the opening can still feel wrong in the room. Ceiling height, wall width and the volume of the space all decide whether the flame reads as proportionate or apologetic.

• Flame presence and visual weight. A compact flame, a long quiet line of fire, or a broad commanding spread. This is the aesthetic call, and it is the one most people start with and should finish with.

All three models are retrofit bioethanol inserts for an existing firebox, secured with ground-fixing brackets, with no chimney sweep, no gas line and no flue rebuild involved. If you are still weighing whether a clean-burning ethanol insert is the right move for a disused hearth in the first place, our bioethanol fireplace grates collection sets out how the format works before you commit to a size.

Before you compare a single model, measure the opening you are working with, because a bioethanol grate has to sit fully inside the firebox with its fuel reservoir and flame contained, not perched at the mouth the way an old wood basket might. The wood-grate conventions you will find elsewhere, the three-inch-here, six-inch-there rules of thumb, were written for log fires that needed airflow under and around the burning wood. A self-contained ethanol unit follows a different logic: it needs room to sit cleanly within the opening and operate with the correct clearances around the burner.

Record four numbers before you go any further:

1. Front width. Measure the opening at the very front, lintel to floor of the firebox. This is the dimension that does the most filtering, because each model carries a minimum firebox width it cannot go below.

2. Rear width. Many fireboxes taper toward the back. Measure the rear separately so you know the unit will clear the narrowest point.

3. Depth. Front face to back wall. Depth decides whether the unit and its required rear clearance fit without the flame sitting proud of the opening.

4. Opening height. Floor of the firebox to the underside of the lintel. Each model needs a minimum height for safe operation and for the flame to read correctly within the frame.

As a guide to where each model lands, the smallest unit in the range suits openings from roughly 650 mm [25.6 in] of front width upward, the mid-size model wants around 800 mm [31.5 in] or more, and the largest needs about 1,000 mm [39.4 in] before it has room to breathe. Those are minimums, not targets. A firebox comfortably above the minimum gives you cleaner clearances and an easier install.

If your firebox is irregular, angled, or built on a curve, measure the most restrictive point in each direction rather than the average. An old masonry opening that narrows sharply at the back can defeat a unit that looked fine on front width alone. And because these are flueless inserts, a blocked or capped chimney is no obstacle to fitting one, which is exactly why they suit hearths that have been out of use for years. The modern fireplace grates in this range are designed to bring those openings back into service without touching the flue at all.

The Grate 18 is the model you choose when the room asks for restraint rather than spectacle. It is the smallest unit in the range, sized for the original Victorian or Edwardian opening, the compact apartment hearth, the bedroom, the study, the second sitting room where the fire is a quiet companion rather than the headline act. In a small, well-proportioned room, a modest flame reads as considered. Drop something far larger into the same space and it stops being a fireplace and starts being a furnace you happen to own.

All three models share EcoSmart Fire's Fluid Concrete surround construction and Grade 304 stainless steel burners, so the choice between them is about scale and flame, not about build quality. Small, here, is a design decision, not a compromise. A compact flame in a tightly framed period surround has a particular intimacy that a wide spread simply cannot reproduce, and the proportions of an older fireplace were drawn for exactly that kind of fire. There is a reason designers so often build a whole room outward from a small original hearth rather than ripping it out for something grander.

What surprises people about this model is that the smallest grate is not the gentlest performer. The AB8 burner inside the Grate 18 produces the highest heat output of the three units, 6 kW (20,433 BTU/hr), and runs for seven to nine hours on a single fill. In markets where EN 16647 applies, the included AB8 Burner Efficiency Ring must be fitted before operating indoors; it is already in the box, and the installation instructions walk through placement. That output also has one counter-intuitive implication worth naming: the AB8 needs an air volume of at least 116 m³ [4,096 ft³] to operate correctly, larger than the room requirement for either of the bigger models. A compact grate in an adequately sized room works exactly as it should; the same grate in a very small space does not. Compact in the opening does not mean undemanding of the space, and it is a point the photographs will never tell you.

The Grate 30 is the model most standard living rooms are quietly asking for. It steps up to the conventional living-room firebox, the kind of opening you find in the majority of homes built for a fireplace in the front room, and it delivers a generous, anchoring presence without tipping into statement-piece territory. If the Grate 18 is a companion and the Grate 36 is a centrepiece, this one is the dependable heart of the room, reinvigorating a disused traditional hearth just as readily as it settles into a clean contemporary surround.

Its real signature is the flame itself. The XL500 burner produces a long, low flame line in a compact body, the kind of fire that draws the eye along its length rather than up in a single tall column. That long-flame character is why this model suits narrower openings so well: it gives you visual breadth and movement without demanding the wide firebox the largest model needs.

It is also the most patient of the three on fuel. The XL500 burner is the most efficient in the range, drawing as little as 0.5 L/h [0.13 gal/h] at full output and running ten to thirteen hours on a single fill, the longest burn of any of the three units. That matters more than it sounds in a primary living space, where a fire lit early in the evening should still be going strong when the last guest leaves. You can read more about what governs that rhythm across the ventless fireplace grates in this collection, but the short version is that a long burn and a long flame rarely come in the same compact package, and here they do.

The Grate 36 exists for the rooms where the fire is meant to be the architecture, not an accessory to it. Wide period openings, open-plan living zones, double-height volumes, hotel lounges and reception spaces, the projects where a designer wants the hearth to hold a large wall on its own. This is the broadest unit in the range, the heaviest at 20.66 kg [45.5 lb], and the one built, in the brand's own words, to make an impact. In the right volume, it does exactly that.

The XL700 burner gives it a long, elegant flame with real breadth, a wide horizontal sweep of fire that carries across a generous firebox and reads cleanly from across a large room. The XL700 burner delivers 4 kW (13,650 BTU/hr) and runs nine to twelve hours per fill, enough warmth and enough endurance to anchor an evening in a sizeable space. Architects and specifiers tend to gravitate to this model because its visual weight matches the scale of the rooms they design, where a smaller flame would simply disappear against a tall wall or a long sightline.

The same quality that makes the Grate 36 commanding in a large space makes it wrong for a modest one. Put it into a snug front room and it overwhelms, both visually and in the way it dominates the wall it sits on. A flame scaled for a double-height lounge looks restless and outsized in a small space. Bigger is only better when the room can carry it, which is why this model rewards a proper read of the space before the firebox tape measure even comes out.

Here is the whole decision on a single screen. The figures below are the ones that actually move the choice; the experiential differences are in the sections above. One row pair is worth reading carefully: average heating area is the floor area the burner can warm, while minimum room size is the total air volume the combustion needs to operate safely, so the two figures answer different questions and do not move together.

A grate that fits the firebox perfectly can still be the wrong grate for the room. The opening tells you what will physically install; the room tells you what will look right once it is lit. Those are two different questions, and the second one trips up more people than the first, because it is easy to measure an opening and hard to judge a proportion.

A flame that is correctly sized for the firebox but undersized for the room reads as timid; a flame oversized for the room dominates every other element in it. Proportion, not fit, is what separates a fireplace that belongs from one that merely works.

Think about the vertical first. A tall wall or a double-height ceiling swallows a small flame, so a room with height needs more flame presence than its floor area alone would suggest. Then read the horizontal: the width of the wall the fireplace sits on, the run of joinery or stone around it, and how much of that wall the fire is meant to command. A long, low flame line carries a wide contemporary surround far better than a compact column does. Architecture and design publications return to this point constantly, describing the hearth as a spatial anchor that holds an open plan together, a role that only works when the flame is scaled to the volume it is anchoring.

Sightlines and seating matter too. A fire that is the focal point from the sofa needs enough presence to hold attention at that distance, while one tucked to the side of an open-plan zone can be quieter and still do its job of defining the space. In frameless and minimalist contemporary installations, where there is no mantel or surround to do the visual work, the flame is carrying the entire composition, so getting its scale right against the room is not a finishing touch. It is the whole design.

Each model carries UL 1370 listing, EN 16647 BSI certification, and ACCC compliance, the triad of safety credentials behind EcoSmart Fire installations across 75 countries. That is the backdrop to the decision; here is how to work it through.

Run the choice in this order and it resolves cleanly:

1. Start with firebox fit. Take your four measurements and eliminate any model whose minimum opening you cannot meet. This is non-negotiable and it usually removes at least one option immediately.

2. Narrow by room scale. Of the models that fit, ask which flame presence suits the volume of the room, its ceiling height and the wall the fireplace anchors. This step almost always points to a single model.

3. Settle on flame and look. If two models survive the first two steps, choose on flame character: the compact intimacy of the AB8, the long low line of the XL500, or the broad elegant sweep of the XL700.

A few edge cases are worth naming, because they are where the order above earns its keep.

If your firebox sits between two model ranges, fitting one comfortably and the other only just, take the comfortable fit. A grate with generous clearance installs more cleanly and looks more deliberate than one wedged in at its limit. If you are torn between flame drama and longer burn, recognise that you are usually choosing between the largest unit's commanding sweep and the mid-size unit's marathon endurance, and let the room decide: a space you fill for long evenings rewards the longer burn, a space built to impress rewards the spread. And if you have a generous open-plan room but only a modest existing firebox, fit is still the gate, so size to the opening, then use focused lighting directly above the surround and a clear sightline from the main seating position; a well-lit smaller flame at the correct eyeline carries more presence than its dimensions suggest.

Whichever you land on, the installation itself is the reassuring part. Each model is secured into the existing firebox with ground-fixing brackets, with no flue rebuild and no chimney work required, though any live gas or solid-fuel connection in the old fireplace must be safely disconnected by a qualified professional first. For most disused hearths, that step has already been done, the old connection capped and cold, which means the installation reduces to bracket placement and seating the burner. The fireplace conversion grates in this range are designed precisely to bring a disused opening back to life without major building work. Each model also ships with a model-specific instruction set covering ventilation, clearances, and indoor placement, everything a clean installation needs. Keep the space well ventilated, observe the clearances for your burner, and the fire operates safely as a design feature in a lived-in room.

What size bioethanol grate do I need for my fireplace?

Start from your firebox's internal front width, because each model carries a minimum opening it cannot go below: roughly 650 mm [25.6 in] for the smallest unit, around 800 mm [31.5 in] for the mid-size model, and about 1,000 mm [39.4 in] for the largest. Eliminate any model your opening cannot meet, then choose between the survivors on room scale and the flame presence you want.

How do I measure a firebox for a retrofit grate?

Record four numbers: the front width, the rear width (fireboxes often taper toward the back), the depth from front face to back wall, and the opening height from hearth floor to the underside of the lintel. Measure the most restrictive point in each direction if the opening is irregular or angled. A bioethanol grate has to sit fully inside the firebox with its fuel reservoir and flame contained, so a comfortable fit with clearance to spare always installs better than one squeezed in at the limit.

Why does the smallest grate need the largest room?

It comes down to the burner, not the footprint. The AB8 burner inside the smallest unit produces the highest heat output of the three, 6 kW (20,433 BTU/hr), and a higher output requires more air volume to operate cleanly, which is why its minimum room size, 116 m³ [4,096 ft³], is the largest in the range. Physical size and burner behaviour do not move together, which is exactly why choosing on dimensions alone can mislead.

Which grate has the longest burn time?

The mid-size model has the longest burn of the three. The XL500 burner inside it runs ten to thirteen hours on a single fill and is also the most fuel-efficient in the range, drawing as little as 0.5 L/h [0.13 gal/h] at full output. That combination of a long flame line and a long burn in one compact body is unusual, and it is the main reason the model suits primary living spaces where a fire is lit for a whole evening.

Can I fit a bioethanol grate if my chimney is blocked or capped?

Yes. These are flueless inserts, so a blocked, capped or damaged chimney is no obstacle to fitting one, which is precisely why they suit hearths that have been out of use for years. Where a unit is installed into an existing masonry opening with a working flue, the damper should be adjusted and a non-combustible, heat-reflective panel fitted across the flue opening, and the room must still be well ventilated whenever the fire is lit.

Choosing between the Grate 18, Grate 30 and Grate 36 is not a contest the largest model wins by default. It is a sequence: the firebox decides what can install, the room decides what will look right, and the flame decides between whatever is left. Run it in that order and the model that suits you stops being a guess and starts being obvious.

What makes these three worth comparing carefully is how little their behaviour tracks their size. The smallest unit runs the hottest burner and wants the most air; the mid-size model burns the longest and sips the least fuel; the largest carries a room that the other two would be lost in. Size on a spec sheet and presence in a real space are different things, and the gap between them is where most sizing mistakes happen.

Get the match right and the fire holds the room together without ever announcing the effort it took to get there. A grate scaled to its space is the one nobody comments on, because it simply looks like it was always meant to be there.