Finnmark Trinity FD-4 vs. FD-5 Trinity XL: Size, Power & Price Compared

By Jerry Vaiana | Collective Relaxation | Updated August 2026 | 12 min read

The Finnmark Trinity line combines infrared heat, traditional Finnish steam, and red light therapy in a single cabin — available in two sizes.

Finnmark's Trinity line is unique in our catalog. It's the only hybrid sauna system we carry that combines infrared heat, traditional Finnish steam, and red light therapy in a single cabin. And it comes in two sizes.

The FD-4 and FD-5 Trinity XL share the same core technology. However, they're built for different rooms, different budgets, and different households. Here's exactly what separates them.

FD-4 vs. FD-5: The Core Difference

Both saunas in Finnmark's Trinity line run the same three systems in one cabin. Specifically, you get Spectrum Plus™ infrared heaters, a traditional Finnish steam heater, and Spectrum Red Light™ therapy. Neither model forces you to choose one heat type over another. Instead, you pick per session.

So what's the real difference? Essentially, it comes down to size, power, and what that means for installation.

The FD-4 is a 2-person cabin. It's built to run on a standard household 120V outlet, so no electrician is needed. The FD-5 Trinity XL, on the other hand, is a larger 4-person cabin with more than double the room volume. However, its traditional heater steps up to 4.5kW on a 240V circuit, which typically does require an electrician to install.

The rule of thumb: if you're outfitting a small room or don't want to touch your home's electrical panel, then the FD-4 is the simpler install. But if you have the space and want real family capacity, the FD-5 Trinity XL is worth the higher price and the electrical work.

Comparison Chart

🔥 Finnmark FD-4 Trinity — 2-Person

The FD-4 is the more compact of the two Trinity models. Specifically, it's sized for one or two people. Importantly, it runs entirely on a standard 120V/15A outlet. Furthermore, the infrared system, the traditional Harvia Vega heater, and the red light panel are all powered from that same common household circuit. As a result, most installs don't require an electrician.

• Infrared: Spectrum Plus™ short-wave heaters reach up to 170°F
• Traditional steam: 1.9kW Harvia Vega heater with vulcanite stones
• Red light: 192-diode LED panel at 650nm with chromotherapy
• Controls: Touchscreen LCD with Bluetooth audio and dual Hi-Fi speakers
• Build: Cedar interior, Thermo-Aspen exterior, 8mm tempered glass door

Honest trade-off: at 86 cubic feet of room volume, the FD-4 comfortably fits one person stretched out or two people seated. However, it's not built for a family session. Therefore, it's the right pick when space and simple installation matter more than capacity.

Who it's for: solo users or couples, apartments and smaller homes, anyone who wants to avoid an electrician visit, and buyers prioritizing a lower price point within the Trinity line.

🌿 Finnmark FD-5 Trinity XL — 4-Person

The FD-5 Trinity XL is the larger cabin in the line. Specifically, it offers more than 50% more exterior footprint and roughly 50% more room volume than the FD-4. Because of the bigger space, the traditional heater steps up to a 4.5kW Harvia unit on a 240V circuit. Consequently, this delivers faster heat-up and higher sustained output.

• Infrared: Spectrum Plus™ system scaled for the larger cabin, up to 170°F
• Traditional steam: 4.5kW Harvia heater with vulcanite stones, up to 190°F
• Red light: same 192-diode LED panel at 650nm with chromotherapy
• Controls: 5" touchscreen LCD controller with Bluetooth audio
• Operating cost: roughly 30–40¢/hour on infrared mode, 50–65¢/hour on traditional mode

Honest trade-off: the 240V circuit requirement means most FD-5 installs need an electrician. Because of this, that adds a real cost and step beyond the sauna itself. So, factor that into your total budget alongside the $1,200 price gap over the FD-4.

Who it's for: families or households that want to use the sauna together, buyers with space for a larger footprint, and anyone already planning an electrical upgrade for other equipment.

Installation: The Power Difference That Matters Most

The single biggest practical difference between these two saunas isn't size. Instead, it's electrical requirements. And that directly affects your total cost and install timeline.

The FD-4: A Simple Plug-and-Play Install

The FD-4 runs on a standard 120V/15A household outlet. Every system — infrared, traditional heater, red light — draws from that same plug-and-play connection. Because of this, for most homes, this means no electrician and no panel work. You simply plug it in and go.

The FD-5: What to Budget for Electrical Work

The FD-5 Trinity XL is different. Its traditional heater requires a dedicated 240V/1PH circuit, the same class of circuit as an electric dryer or range. So unless your install location already has 240V service nearby, this typically means hiring a licensed electrician to run a new line. As a result, that adds both cost and time to your installation beyond the sauna's purchase price.

Budget accordingly: when comparing the $7,795 FD-4 to the $8,995 FD-5, the real cost gap is often larger than $1,200. That's because you also need to factor in potential electrical work for the FD-5. So, before ordering, get a quote from a local electrician, especially if you're not sure whether your space already has 240V service.

Either way, both models ship via freight delivery by special appointment. Specifically, they arrive on a wooden pallet with curbside delivery — the driver lowers the unit to ground level but doesn't carry it inside. Consequently, both require assembly on arrival.

Which Size Do You Need?

• Solo or couple use → FD-4 Trinity ($7,795) — simpler install, lower price
• Want to skip the electrician → FD-4 Trinity — runs on a standard household outlet
• Family sessions, more room to move → FD-5 Trinity XL ($8,995) — 4-person capacity
• Already planning electrical upgrades → FD-5 Trinity XL — the 240V requirement is less of a hurdle if you're already there
• Tightest budget within the Trinity line → FD-4 Trinity — lowest total cost including install

Frequently Asked Questions