EOS Invisio Midi 9 kW Electric Sauna Heater

The EOS Invisio Midi 9 kW is a floor-standing electric sauna heater rated at 9 kW, for rooms of 50.5-79.7 sq ft at a 6.2 ft ceiling (about 313-494 cu ft). Available on 208V 3Ph or 240V 2Ph, in anthracite or stainless steel. Sauna stones are not included. It ships without controls and takes an EOS Touch 3 or EmoTec D control, sold separately.

Invisio Midi is a wide, low convector built to disappear under a bench, 45.7 in across but only 15 in deep, on height-adjustable legs that set it between 28 and 30.3 in tall. A protective grill covers the top so nothing can fall onto it, and a full-width water channel spreads an infusion evenly along its length.

These are not included. You need them before the sauna will run.

Figures are from EOS's North America installation manual and datasheet for this heater. Breaker and conductor sizing remains your electrician's call under the NEC and local code.

The minimum distances EOS publishes for this heater. Measure before you frame the bench.

The protective grill is supplied with the heater. These are minimums to combustible material, not recommendations. The installation manual and your local code take precedence.

This page is the 9 kW Invisio Midi. EOS rates it for 50.5-79.7 sq ft of floor area at a 6.2 ft ceiling, about 313-494 cu ft.

EOS sizes its heaters by floor area at a 1.90 m / 6.2 ft ceiling rather than by volume. Measure your floor, then add allowance for anything that absorbs heat instead of reflecting it, glass, tile, concrete, stone and exposed log all make a room behave larger than it measures. If you fall between two outputs, size up.

Other outputs in the Invisio Midi range

Work out your room with the sauna heater size calculator

• EOS heaters ship without controls. The control mounts outside the hot room and switches the heater through a separate power box.
• Mount to the clearances published above.
• The cabin needs an air inlet and outlet of at least 35 x 6 cm (13.8 x 2.4 in), and an air exchange of five times the cabin volume per hour.
• Hardwired on a dedicated circuit by a licensed electrician. EOS specifies a fuse of 40 A (adjustable to 35 A) on 208V 3Ph; 20 A on 240V 2Ph, on copper conductors rated for at least 90 °C.
• Stones are not supplied. Load them loosely by hand so air moves between them, and never run the heater with an empty rock store.

EOS's North America documents for this heater. The manual carries the wiring table, the clearance diagrams and the air inlet sizes. The control is a separate product and its manual is on its own page.

• Installation and operating instructions (PDF)
• Datasheet (PDF)

What size room does the 9 kW EOS Invisio Midi heat?

EOS rates this output for 50.5-79.7 sq ft of floor area at a 6.2 ft ceiling, which works out to roughly 313-494 cu ft. EOS sizes by floor area rather than volume. Add allowance for glass, tile, stone or concrete, and size up if you fall between two outputs.

What circuit does the 9 kW EOS Invisio Midi need?

A dedicated circuit on the supply you choose. EOS specifies a fuse of 40 A (adjustable to 35 A) on 208V 3Ph; 20 A on 240V 2Ph, on copper conductors rated for at least 90 °C. Your electrician sizes the breaker and conductors to the installation manual, the NEC and local code.

Which control does the EOS Invisio Midi need?

Either an EOS Touch 3 or an EOS EmoTec D/H (USA/CAN), EOS's North America datasheet lists both for this heater, and its installation manual names the EmoTec D/H. The heater cannot run without one. The control mounts outside the hot room, which is what lets you bring the sauna up to temperature before you walk in, and it switches the heater through a separate power box.

Do I need stones for the EOS Invisio Midi?

The Invisio Midi holds 20 kg / 44 lbs of stones at a 50-100 mm (2-4 in) caliber, and they are not included. EOS lists them as an optional accessory in its North America manual. The heater makes steam from a full-width water channel rather than relying on the rock mass alone, which is unusual, but it is still designed to run with its rock store filled. One 44 lb box covers it.

Is the EOS Invisio Midi UL listed?

EOS publishes no UL, ETL or CSA listing for its heaters. Its North America manual requires UL 875 labelling and states that the temperatures settable from the control are tested to UL 875 or CSA C22.2#60335-1:2016 Ed.2 and CAN/CSA E60335-2-53, which is not the same as a listing. Some jurisdictions and insurers require a listed appliance, so confirm before you buy.