Short answer: the FD-5 Trinity XL is a 4-person indoor hybrid with a 2,700W infrared array and a 4.5kW Harvia heater for $8,995. It carries the strongest listed warranty of the hybrids here. It also needs a dedicated 240V circuit, and our data has a plug detail you should question.
What circuit does it need?
The listing states 240V at 18.8A. That matches the 4.5kW heater: 4,500W divided by 240V is 18.75A. The infrared array adds about 11.3A at 240V if it runs at the same time, so ask the dealer whether the two can run together and what breaker size the manual specifies.
Here is the detail to question. Our data lists a “NEMA 5-15P plug” next to the 240V requirement. A 5-15P is the ordinary 120V household plug, so those two facts don’t fit together. Ask the dealer for the installation manual and hand it to your electrician before you buy.
Is 4.5kW enough for this room?
The interior is 71” x 57.5” x 75.5”. Multiply and divide by 1,728 and you get about 178 cubic feet. Harvia rates its 4.5kW heater for 100 to 210 cubic feet, so the room sits inside the range.
What does it cost to run?
Finnmark estimates $0.30 to $0.40 per hour on infrared mode. My own arithmetic agrees: 2.7 kWh per hour at the 2026 US average of 18.34 cents is about $0.50 at full power, and the panels cycle. The traditional heater at full power is about $0.83 per hour.
What the listing leaves out
The weight isn’t published. The exterior is 75” x 64” x 83”, about 33 sq ft, so ask for the weight and the size of the largest panel before planning delivery. On warranty, The Sauna Place lists 10 years on the sauna and lifetime on the infrared heaters, while Select Saunas mentions 2 years on the traditional heater. Get the terms that apply to your order in writing.
How it compares
The FD-4 Trinity is the 2-person, 120V version at $7,795. For the full write-up, read our FD-5 Trinity XL review.
