Harvia M3 Wood Fired Sauna Stove

Your Harvia M3, configured around your sauna

The M3 brings a glass-fronted wood fire to a compact sauna. Its 16.5 kW output serves rooms from 212 to 459 adjusted cubic feet; glass, masonry and log construction affect the size calculation.

Configure your Harvia M3 and accessories in 3D ↑

Choose where you load the fire

The standard M3 is loaded inside the sauna. Choose the M3 SL through-wall stove to load from the adjoining space. The SL has a real fire chamber extension and different installation details; it is not an ordinary M3 pushed through a wall.

See the actual installation and your selected package

The gallery includes our real 360° photographs of an M3 installed in a SaunaLife G4. Use the tour to look around a finished installation, then switch to Configure in 3D to see your selected stove and accessories. The photographs show the installed G4; they stay unchanged when you configure your package.

Enter your room dimensions and uninsulated surface area, compare the layout and review the selected components. The configurator keeps the package choices together; your installer confirms the foundation, wall construction, ventilation and complete chimney route.

Build the whole installation

• Stones: add two 44 lb boxes of Harvia AC3020. The stove holds up to 66 lb, so keep the surplus rather than loading all 88 lb. Use the specified 4 to 6 in sauna stones and leave air passages between them.
• Floor protection: Harvia WL100 protective bedding protects the supporting surface where required, including a tiled floor with a water barrier. Its feet raise the stove 2.36–2.96 in; include the installed height in ceiling and SL wall-opening checks. Protection in front of the loading door is separate.
• Wall protection: Harvia WL450 protects both sides and the rear. Keep at least 1.97 in from the outside of the fitted sheath to combustible walls or benches. The separate WL400 one-sided sheath protects only the selected left or right side; the opposite side and rear retain their unprotected clearances. Stove-to-sheath mounting space is additional to the outside clearance. Neither sheath removes chimney, ceiling or loading-door requirements.
• Chimney system: choose the matching WHP1500 chimney kit in stainless steel or black, or the flat-roof and barrel chimney package. These are alternative complete kits, so choose one. The WHP1500 has 59.1 in of insulated chimney plus a 39.4 in uninsulated connector. Its cap and specified roof/ceiling components are included; the WHM25 vapor-barrier collar is separate.
• Chimney height and roof: add the measured 39.4 in extension, 19.7 in extension, WHM25 vapor-barrier collar, insulated damper and the appropriate roof components. Keep joints outside the ceiling and roof penetration; the chimney schedule determines the parts and support.
• A different chimney system: the WZ115155 adapter connects the stove-size pipe to a 6 in system. It is an alternative to the matching Harvia kit, not an extra fitting needed with that kit. The installer must approve the complete connection and listed chimney system.
• Hot water: the optional WP220ST pipe-model water heater fits the top flue outlet and holds 5.8 gallons. Keep the filling opening upward and the faucet accessible. Its upper connecting pipe needs at least 19.69 in to combustibles when unprotected, or 9.85 in with the specified radiation shield. Where stove protection does not shield nearby combustibles from that pipe, install WZ020130 as directed. The stove sheath alone does not protect the pipe above the tank. Keep water in the tank while heating.

Use Harvia WHP chimney systems only for standalone outdoor sauna buildings. For a residence or attached building, use an installer-designed chimney system approved for that application.

Plan the floor, walls and ceiling together

Keep at least 47.25 in between the stove top and the ceiling. Include any protective bedding and foot adjustment when checking the installed height. The protective sheath changes only the clearances specified for that exact assembly. Combustible materials, noncombustible walls, the loading door and connecting pipe have separate requirements.

The standard M3 supports top or rear flue connection as specified in its manual. Choose the connection before finalizing the stove position, floor protection and chimney components.

Installing an M3 SL through a wall

The M3 SL fire chamber extension passes through a specified noncombustible wall. The general SL limit is 5.90 in of concrete or brick. The opening must be at least 8.67 in wide and 15.36 in high above the stove support level. Raise the opening by the installed base height; WL100 raises the stove, tunnel and door together by 2.36–2.96 in. Provide separate loading-side floor protection.

WL400 and WL450 are supported on M3 SL. With WL400, choose left or right protection; rear and opposite-side clearances still apply. With either sheath, use a concrete or brick feed wall no thicker than 4.92 in. A wall thicker than 4.92 in and up to the general 5.90 in SL limit needs Harvia confirmation for the sheath arrangement. The sheath does not make a wood-framed feed wall noncombustible or protect the loading room and ceiling.

When M3 SL connects to a Harvia steel chimney, the noncombustible feed wall must extend to the roof. The exception is an appropriate thin noncombustible wall system that permits the specified chimney offset. Keep at least 3.94 in from combustible structures to the chimney’s outer casing. A masonry facing over timber does not meet the noncombustible-wall requirement.

Keep the M3 serviceable

The M3 and M3 SL use different ash boxes: ZKIP-720 is the 14.17 in standard M3 ash box; Z2ES-125 is the 21.50 in M3 SL ash box. They are not interchangeable. The SPZKIP-10 grate and SPZTS-36 glass pane support both stove models; match the stove and door revision before ordering. The glass is the pane only, not a complete door. Empty the ash box as directed, inspect the flue and keep combustion-air passages clear.

View the Harvia stove-parts drawing. Current service-part ordering information is in the 3D configurator’s parts section.

What comes with the stove?

The stove includes its door, ash box and installation instructions. Stones, protective bedding, wall sheath, chimney system and water heater are selected separately. Two boxes of stones supply extra material for a permitted 66 lb charge; the supplied box weight is not the amount to load.

Read the current Harvia M-series installation and operation manual. Use the model table and the separate SL instructions for the exact stove selected.

Read the M3 SL through-wall installation instructions. Read the WL400/WL450 sheath instructions.

Planning guides: Sauna heater calculator · Wood sauna stove guide