Finnmark FD-4 Trinity 2-Person Hybrid Indoor Infrared & Traditional Steam Sauna
The Finnmark FD-4 Trinity is a 2-person hybrid sauna that puts infrared heat, a traditional Harvia rock heater for steam, and red light therapy in one cabin. Six UL-listed Spectrum Plus™ infrared heaters take the cabin up to 170°F, while the Harvia Vega Compact 1900 heater reaches up to 190°F when you pour water over the stones. The cabin is built with a Thermal Plus™ European Aspen exterior and a clear A-grade Western Canadian Cedar interior with a two-tier bench.
Infrared, steam, and red light in one cabin
Use the infrared side for a lower-temperature session, switch to the Harvia heater for a traditional sauna with steam, or use both. The six Spectrum Plus™ dual-wave heaters are UL-listed Incoloy elements that produce mid and far infrared, carry 0.99 emissivity, and are rated for about 40,000 hours. Above the bench, a Spectrum Red Light panel with 192 LED diodes at 650nm sits next to chromotherapy color lighting.
Thermal Aspen outside, cedar inside
The exterior is Thermal Plus™ European Aspen, a wood that is heat and steam treated with no chemicals and is made to resist rot, warping, decay, and chipping. Inside, the walls and the two-tier bench are clear A-grade Western Canadian Cedar, which is naturally antimicrobial. Tongue and groove, double-walled construction with non-toxic wool insulation and an 8mm tempered glass door with a gasket help keep the heat inside the cabin.
Harvia Vega Compact 1900 heater
The traditional side runs on a Harvia Vega Compact 1900, a 1.9 kW, 120V stainless steel electric heater made in Finland and mounted on the front interior wall. It is rated for rooms of 70 to 106 cubic feet and comes with one 29 lb box of Harvia AC3000 stones; an extra box is recommended so you can choose the best stones. The heater has no power cord and must be hardwired by a licensed electrician on its own dedicated circuit.
Controls and certifications
The V2 LCD controller puts a 5" touchscreen inside the cabin for temperature, lighting, and music, with Bluetooth audio through 6" marine-grade HiFi speakers and remote start from your phone. The infrared side runs on 120V 15A NEMA 5-15 (x2). The cabin is ETL certified, the Spectrum Plus™ heaters are UL listed, and EMF levels are third-party tested. You can review the test log and certificates in the documents below.
Specifications
Dimensions & capacity
| External dimensions |
48" W × 48" D × 83" H |
| Internal dimensions |
44.5" W × 45" D × 75" H |
| Interior volume |
86 cu. ft. |
| Door opening |
23.625" W × 68.75" H |
| Door handle |
1.5" W × 13.25" H |
| Capacity |
2 people |
| Bench |
Two-tier cedar bench
Top 44.5" × 19", lower 44.5" × 15" |
| Product weight |
437 lbs |
| Shipping weight |
485 lbs (incl. 48 lb pallet) |
| Minimum ceiling height |
86.1" |
| Clearance |
3" on every side |
Construction & materials
| Exterior wood |
Thermal Plus™ European Aspen (heat and steam treated) |
| Interior wood |
Clear A-grade Western Canadian Cedar |
| Walls |
Tongue & groove, double-walled
Non-toxic wool insulation |
| Glass |
8mm tempered glass door with gasket |
| Feet |
Removable, adjustable |
| Placement |
Indoor sauna
Outdoor only with an outdoor cover
On a level, dry, hard surface under an overhang |
Infrared system
| Infrared heaters |
6 Spectrum Plus™ dual-wave heaters
(mid and far infrared, UL listed) |
| Heater lifespan |
Approx. 40,000 hrs |
| Emissivity |
0.99 |
| Infrared power |
1,750W |
| Max temperature |
170°F (77°C) |
| Red light |
192 LED diodes, 650nm, with chromotherapy |
| EMF rating |
Low EMF/ELF (third-party tested) |
Traditional (steam) system
| Heater |
Harvia Vega Compact 1900 |
| Power |
1.9 kW, 120V, single phase, 15.9A |
| Heater type |
Wall-mounted, stainless steel |
| Heater size |
11" W × 11" D × 21" H, 15.4 lbs |
| Room size |
70 to 106 cu. ft. |
| Sauna stones |
1 box Harvia AC3000 (29 lbs) included |
| Max temperature |
190°F (88°C) |
Electrical & controls
| Infrared power supply |
120V 15A NEMA 5-15 (x2) |
| Harvia heater power supply |
120V / 20A dedicated circuit
Hardwired by a licensed electrician |
| Power cord |
9 ft |
| Controller |
V2 LCD controller, 5" touchscreen |
| App control |
Remote start from your phone |
| Audio |
Bluetooth with 6" marine-grade HiFi speakers |
Certifications
| UL Listing |
Yes, Spectrum Plus™ heaters |
| ETL Certification |
Yes, cabin (Intertek infrared sauna safety) |
| EMF Test Log |
Available (PR108242) |
| Finnmark Certification |
Available |
What's included
Bottom, top, back, front, left and right panels
8mm tempered glass door
Bench support and bench top
Spectrum Plus™ infrared heater panels
Harvia Vega Compact 1900 heater
1 box Harvia AC3000 stones (29 lbs)
LED red light panel (650nm) with chromotherapy
V2 LCD controller with Bluetooth audio
Interior heater connections with wood cover
Heater cable and floor cable
Power supply unit and power cable
Door handle (with 2 screws)
Removable, adjustable feet
Assembly screws
ETL certification and limited warranty
Why the Finnmark FD-4 Trinity stands out
Infrared and steam in one
Six Spectrum Plus™ infrared heaters and a Harvia Vega Compact 1900 rock heater share one cabin. Use either one, or both together.
Spectrum Plus™ heaters
UL-listed Incoloy dual-wave heaters produce mid and far infrared, carry 0.99 emissivity, and are rated for about 40,000 hours.
Harvia Vega heater
A 1.9 kW, 120V stainless steel heater made in Finland. Pour water on the stones for steam at up to 190°F. Stones included.
Red light therapy
A 192-diode, 650nm Spectrum Red Light panel above the bench, with chromotherapy color lighting beside it.
Thermal Aspen and cedar
Chemical-free Thermal Plus™ Aspen exterior with an antimicrobial Western Canadian Cedar interior and two-tier bench.
UL listed & ETL certified
Spectrum Plus™ heaters are UL listed and the cabin is ETL certified. EMF levels are third-party tested; documents are below.
About Finnmark Designs
Hybrid home sauna
Infrared and traditional heat in one 2-person cabin
Finnmark Designs builds its saunas around Spectrum Plus™ infrared heaters, low EMF/ELF performance, and natural woods. The FD-4 Trinity adds a Harvia Vega traditional heater and a red light panel to that setup, so two people can choose infrared, steam, or both in the same cabin.
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Infrared and steam, use either one or both together
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6 Spectrum Plus™ heaters, mid and far infrared, UL listed
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Harvia Vega Compact 1900, 1.9 kW with 29 lbs of stones
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Red light therapy, 192 diodes at 650nm
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ETL certified, third-party EMF tested
About Finnmark Designs
Built for the home, backed by documentation
The FD-4 Trinity ships as a DIY kit that two people can assemble with a screwdriver and a level. The infrared side plugs into a standard 120V outlet, while the Harvia heater is hardwired by a licensed electrician on its own circuit.
From the third-party EMF test log to the UL listing and the ETL certificate, Finnmark publishes the documents behind its claims so you can review them before you buy.
Manuals & Documents
Everything you need before and after installation
Download the full Finnmark Designs documentation set below. Review the Trinity Installation & Operation Manual before delivery so you know what to expect on installation day. A licensed electrician is required to hardwire the Harvia Vega heater, which has its own installation manual.
Installation & Operation Manuals
Test Logs & Certifications
Warranty
Warranty
Lifetime
Spectrum Plus™ Heaters
Warranty basics
The Finnmark FD-4 Trinity comes with a 10-year Finnmark Designs sauna warranty, plus an unconditional lifetime warranty on the Spectrum Plus™ Incoloy heaters. The Harvia Vega heater carries its own 2-year consumer warranty. For infrared saunas in the USA, "lifetime" is considered 7 years.
Coverage conditions
The sauna must be installed per the instructions and properly maintained. The Harvia heater warranty requires proper care of the sauna stones. Using the sauna outdoors without an outdoor cover voids the warranty.
Full terms
We are an authorized Finnmark Designs dealer. See the official warranty document above for full terms, exclusions, and claim procedures.
