Sustainable Hearth Electric Fireplaces: A Complete Guide to the Collection

Last reviewed: September 28, 2026

Sustainable Hearth makes five built-in electric fireplace series, and what separates them is not feature count. It is wall depth, viewing configuration, and flame technology. Work through those three and the right series usually announces itself.

If you are...	Start with
Working with a shallow wall	E-FX Slim Line Series, 7 inch depth
Building a custom media wall	E-FX Series
Building on a tighter budget	Signal Series
Prioritizing flame realism above all	TrueFlame 150 3DX
Serving two rooms with one fireplace	Optic 50

How the collection is organized

A note on naming first. Sustainable Hearth is both a business and one of the ranges it sells, and the business also carries a couple of British electric fireplace brands. This guide covers the signature Sustainable Hearth range specifically, which is kept deliberately small.

Every series in the range is a built-in fireplace requiring framing and electrical planning, and most arrive with conversion components that let you choose the final viewing configuration during installation rather than committing to it at order time. If you are new to the brand, our explainer on the change from European Home to Sustainable Hearth covers the background.

Wall depth comes first

Wall depth determines which series are possible in your space, and it splits this range in two: the E-FX Slim Line at 7 inches, and everything else at roughly 11 1/4 inches.

A standard interior wall framed with 2x4 studs gives about 3.5 inches of usable cavity, so every model here needs more depth than a plain stud wall provides. The practical question is how much you are willing to build out.

In practice, this is the problem we hear about most often after the fact. Someone chooses a deep built-in unit, then finds they have around six inches of clearance where the fireplace needs twelve, and the fix is framing the wall out. That is drywall, framing, and finish work that was never in the plan, and it changes how the finished wall sits in the room.

Measure your available depth before you shortlist. If the number is tight, the Slim Line exists for exactly that situation. Our installation cost guide covers what building a wall out typically adds to a project.

E-FX Series

The E-FX Series is the flagship, available in 40, 52, 60, and 72 inch sizes at 11 1/4 inches deep, with every unit shipping as a three-sided fireplace including the components to convert it to single-sided, left corner, or right corner.

That conversion kit is the series' defining trait. On a project where the room layout is still being worked out, or where the millwork drawings change after the fireplace is ordered, you are not locked in. Controls run through a remote, a manual keypad, the app, or compatible voice control, and the hidden heater handles supplemental warmth for spaces up to roughly 1,000 square feet.

Good fit if: you want a premium linear fireplace for a custom media wall or open-concept room and want to decide the viewing configuration during installation rather than before it.

E-FX Slim Line Series

The E-FX Slim Line Series takes the E-FX visual language and compresses it into a 7 inch deep cabinet, across four single-sided models: a 24 inch, a 30 inch, a taller 30 inch, and a 40 inch.

Seven inches is the number that matters. It is what makes this series viable in condos, apartments, offices, and any wall where you cannot give up floor space to framing depth. The taller 30 inch model is worth flagging separately: it has a more vertical viewing area, which reads closer to a traditional fireplace proportion than the wide linear formats do.

Good fit if: you want a built-in fireplace but wall depth is the binding constraint, and a single-sided installation works for the room.

Signal Series

The Signal Series is the value entry into the line, available in 40, 60, and 80 inch sizes and shipping single-sided with conversion components for corner and three-sided installations.

What you give up relative to E-FX is the smart control layer, since Signal is remote-operated without app or voice integration, along with some depth in the log and ember presentation. What you keep is the frameless architectural look and the flexible configuration, at a meaningfully lower cost size for size. For hospitality, offices, and multi-unit residential work where the fireplace needs to look right without carrying the budget of a flagship model, this is usually the answer.

Good fit if: you want the Sustainable Hearth look and configuration flexibility, and app control is not a requirement.

TrueFlame 150 3DX

The TrueFlame 150 3DX is the realism play, using a 4K LCD flame display behind the glass rather than an LED flame effect. The viewing opening is roughly 59 inches wide by 18 inches high, at 11 1/4 inches deep.

Two log packages are offered: a standard Woodland Logs set and an upgraded Real Logs set. The firebox and flame technology are identical between them, and only the log presentation changes. It ships single-sided with conversion components for corner and three-sided layouts, and takes both remote and app control.

The tradeoff is that it comes in one size. If 59 inches does not work for your wall, this series is out and you are back to E-FX or Signal. Confirm exact dimensions on the current cut sheet before framing.

Good fit if: flame realism is the deciding factor, the fireplace is the focal point of a large room or lobby, and 59 inches suits the space.

Optic 50

The Optic 50 is the only true see-through model in the range, with flames visible from both sides. It is built for room dividers and partitions in open-concept homes, hotels, and commercial interiors.

The tradeoff is structural rather than financial. A see-through unit needs a wall that can be opened on both sides, which is a bigger framing decision than a standard recessed install. Confirm the wall is a candidate before committing.

Good fit if: you are designing a partition or divider and need the fireplace to serve two rooms at once.

Three-sided is not the same as see-through

Three-sided and see-through describe different configurations, and confusing them is the single most common specification error with this line.

A three-sided fireplace is viewed from the front and both ends, all from within one room. The E-FX, Signal, and TrueFlame can all be configured this way. A see-through fireplace is transparent through the wall between two separate spaces. If you want people in the kitchen and people in the living room to see the same fire, the Optic 50 is the only model in this line that does it.

Get this wrong at order time and the fix is not a conversion kit. It is a different fireplace. If you are weighing the format more broadly, our guide to see-through and 3-sided electric fireplaces compares them across brands.

How the five compare

Series	Depth	Sizes	Configurations	Controls
Signal Series	Standard	40, 60, 80 in	Single, corner, three-sided	Remote
Optic 50	Standard	50 in class	See-through, double-sided	Remote
E-FX Slim Line	7 in	24, 30, 30 tall, 40 in	Single-sided	Remote, keypad, app, voice
E-FX Series	11 1/4 in	40, 52, 60, 72 in	Single, corner, three-sided	Remote, keypad, app, voice
TrueFlame 150 3DX	11 1/4 in	59 in	Single, corner, three-sided	Remote, app

Current pricing for every model is on the Sustainable Hearth collection page.

Choosing between them

Three questions get you most of the way.

How deep can you frame? Under 11 inches and you are looking at the E-FX Slim Line. At 11 1/4 inches or more, the rest of the range opens up.

How many rooms does the fireplace serve? Two separate rooms means Optic 50. One room means everything else.

Does app control matter? If yes, E-FX, Slim Line, or TrueFlame. If a remote is fine, Signal saves you real money without compromising the look.

Beyond that it comes down to size availability and whether the 4K flame in the TrueFlame is worth the premium, which is something to judge in person if you can. If you are still deciding on format rather than brand, start with built-in vs wall mounted electric fireplaces.

Common mistakes

Confusing three-sided with see-through. Covered above, and the most frequent error with this line. Confirm which one your design calls for before ordering.

Choosing the series before measuring wall depth. The Slim Line and the rest of the range are four inches apart, which is the difference between a straightforward install and framing a bump-out.

Framing before reading the model-specific cut sheet. Every model has its own rough opening, clearance, and electrical requirements, and the corner and three-sided configurations differ from the single-sided ones. The generic series depth is not enough to build from.

Treating Signal as a lesser product rather than a different one. It is not a stripped-down E-FX. It is designed to a different brief, and in hospitality or multi-unit work it is frequently the better specification.

Frequently asked questions

Which Sustainable Hearth model is the shallowest?

The E-FX Slim Line Series, at 7 inches deep, is the only series in the range designed for shallow wall cavities. Every other series needs roughly 11 1/4 inches. Since a standard 2x4 interior wall provides about 3.5 inches of usable cavity, all of these models require either a deeper wall or a built-out framed enclosure.

Which model works as a see-through fireplace between two rooms?

The Optic 50 is the only see-through model in the range. The other series offer three-sided viewing within a single room, which is a different configuration entirely. A see-through installation also requires a wall that can be opened on both sides, so confirm the wall is structurally suitable before ordering.

What is the difference between Signal and E-FX?

Both offer single-sided, corner, and three-sided configurations. E-FX adds app and voice control, a manual keypad, and a more developed flame and log presentation. Signal is remote-operated and sits at a lower price point size for size, while keeping the same frameless look and configuration flexibility.

Which Sustainable Hearth series is the most affordable?

The Signal Series is the value entry into the range, giving you the frameless built-in appearance and the corner and three-sided conversion options without the smart control layer. Current pricing across all five series is on the Sustainable Hearth collection page.

Which model has the most realistic flame?

The TrueFlame 150 3DX, which uses a 4K LCD flame display rather than an LED effect, in a single 59 inch size with a choice of two log packages. If flame realism is your main criterion, it is also worth comparing against the water vapor electric fireplaces collection, which uses a different technology toward the same goal.

Can these fireplaces run without heat?

Yes. Across the range, the flame effect and the heater are controlled independently, so the fireplace can be used for ambiance year-round.

Do these require professional installation?

Yes. Every series in the line is a built-in fireplace requiring correct framing, electrical planning, and finish clearances. Review the model-specific manual before construction begins, and see our installation cost guide for what to budget.

Where to go from here

A small catalog is a feature rather than a limitation. Five series with clear boundaries between them means the specification decision is tractable: measure your framing depth, count the rooms the fireplace serves, decide whether app control matters, and you are down to one or two options.

Browse the full Sustainable Hearth collection to compare them side by side, or see how they sit against the wider market in the built-in electric fireplaces collection.