Harvia Woodburning Sauna Stove: Installation and Use Instructions

Congratulations on your choice! The Harvia sauna stove works best and serves you longest when it is used and maintained according to these instructions. Read the instructions carefully before installing or using the stove. Keep the instructions for future reference.

1. General

Choosing the Stove Model

Choose the stove model carefully. A stove with too low output must be heated longer and more intensely, which will shorten the stove's life span.

Note that non-insulated wall and ceiling surfaces (such as brick, glass, tile and concrete surfaces) increase the output requirement of the stove. For every square meter of such wall and ceiling surface, calculate an additional 1.2 m³ volume. If the sauna walls are made of massive log, the volume must be multiplied by 1.5.

Examples:

• A 10 m³ sauna room with a brick wall 2 m high and 2 m wide is equivalent to a sauna room of approximately 15 m³.
• A 10 m³ sauna room with a glass door is equivalent to a sauna room of approximately 12 m³.
• A 10 m³ sauna room with massive log walls is equivalent to a sauna room of approximately 15 m³.

The dealer or Harvia's factory representative can assist you in choosing the stove if needed. You can also visit the website www.harviasauna.com for further details.

1.1. Stove Parts

Key stove components include:

• A. Upper connection opening
• B. Rear connection opening
• C. Soot opening
• D. Stove door
• E. Ash box

Figure 1: Stove Parts. Only use replacement parts recommended by the manufacturer. Unauthorized modification of the stove is prohibited.

2. Instructions for Use

Read the instructions carefully before using the stove.

2.1. Warnings

• Staying in the hot sauna for long periods can raise body temperature, which may be dangerous.
• Keep away from the stove when it is hot. The stones and outer surface can burn skin.
• Never throw water on the stones when people are near the stove, as hot steam can cause burns.
• Keep children away from the stove.
• Do not let young, handicapped, or ill people bathe in the sauna alone.
• Consult a doctor about any health-related limitations to bathing.
• Consult a child welfare clinic about taking babies to the sauna.
• Be very careful when moving in the sauna, as floors and benches can be slippery.
• Never go to a hot sauna if you have consumed alcohol, strong medicines, or narcotics.
• Never sleep in a hot sauna.
• Sea air and humid climates may corrode metal surfaces.
• Do not hang clothes to dry in the sauna, as this may cause a fire risk.

2.2. Preparing the Stove for Use

Perform the first heating outdoors. The stove body is painted with protective paint that vaporizes during the first heating, causing smoke. Once smoking stops, the stove is ready for normal use. Remove leftover paint mechanically (e.g., with a wire brush and vacuum cleaner).

Install smoke pipes for draught. This will also cause odors to vaporize from the smoke pipes.

The outer casing is painted with heat-resistant paint that cures during the first heating. Avoid rubbing or sweeping painted surfaces before this.

• Sauna stones should not be placed in the stove before the first heating. Place stones only after the stove has cooled completely.
• Stoves with a water container: Clean the water container carefully before use. Fill it before the first heating.

Do not throw water on the stove during the first heating, as painted surfaces can get damaged.

2.3. Burning Material

Dry wood is the best material. Dry chopped firewood clinks when knocked together. Wood moisture significantly impacts burning cleanliness and stove efficiency. Start fires with birch bark or newspapers.

The thermal value of wood varies. Burning large amounts of high thermal value wood shortens the stove's lifespan.

Do not burn the following materials:

• Materials with high thermal value (chipboard, plastic, coal, briquettes, pellets)
• Painted or impregnated wood
• Waste (PVC plastic, textiles, leather, rubber, disposable diapers)
• Garden waste (grass, leaves)
• Liquid fuel

2.4. Sauna Stones

• Stones should be 10–15 cm in diameter.
• Use only proper sauna stones. Peridotite, olivine-dolerite, and olivine are suitable. Natural stones may contain harmful substances (e.g., iron pyrite) and should not be used.
• Wash dust off stones before piling them into the stove.
• Place larger stones at the bottom and smaller ones on top.
• Ensure air circulates between the stones.
• Do not place stones against or on top of the stone space frame.
• Do not place stones between the grate and the stove body.

Figure 2: Piling the stones.

2.5. Heating the Stove

Before heating, ensure no unnecessary items are in the sauna or within safety distances. Extractor fans may cause problems if operated in the same space.

1. Empty the ash box.
2. Place firewood in the fire chamber, allowing space for combustion air. Use firewood with a diameter of 8–12 cm (consider ignition load value from Table 2). Place larger pieces at the bottom, smaller ones on top.
3. Place kindling on top of the firewood. Starting fire from the top produces fewer emissions.
4. Ignite the kindling and close the door. Draught can be adjusted by opening the ash box. The stove is not intended for use with the door open.
5. Note: Handles become hot during use. Use the supplied tool for opening/closing the stove door and ash box.
6. When heating, keep the ash box slightly open initially for proper fire start.
7. Excessive draught can cause the stove body to glow red, significantly shortening its lifespan.
8. During bathing, when the sauna is heated, close the ash box to reduce fire and wood consumption. Refer to Table 2 for optimal ash box gap (measure using holes on the sides).
9. If necessary, add more firewood as embers die down. Use firewood with a diameter of 12–15 cm. A couple of pieces are enough to maintain bathing temperature (consider refuelling loads from Table 2).

Prolonged, intense heating may cause a risk of fire!

• Excessive heating (e.g., several full loads consecutively) can overheat the sauna room, stove, and chimney, shortening lifespan and posing a fire risk.
• Temperatures over 100 °C are generally too high for a sauna.
• Observe correct wood quantities. Let the stove, chimney, and sauna room cool down if necessary.

Figure 3: Tool for opening/closing door and ash box.

2.6. Sauna Water

Use clean household water. Water containing salt, lime, iron, or humus can prematurely corrode the stove. Seawater is particularly corrosive.

Household water quality requirements:

• Humus content: <12 mg/litre
• Iron content: <0.2 mg/litre
• Calcium content: <100 mg/litre
• Manganese content: <0.05 mg/litre

Throw water only on the stones. Throwing water on hot steel surfaces can cause blistering due to temperature variations.

2.7. Maintenance

Stove Maintenance

• Empty the ash box before heating to allow combustion air to cool the fire grate and prolong its life. Use a metal container for ash. Keep ash containers away from combustible material as they may contain hot embers.
• Periodically remove soot and ashes from smoke canals via soot openings (see 1.1.).
• Sauna stones disintegrate due to temperature variations. Rearrange them at least annually, or more often with frequent use. Remove stone pieces and replace disintegrated stones with new ones.
• Wipe dust and dirt from the stove with a damp cloth.

Chimney Maintenance

• Sweep the chimney and connection pipes at regular intervals, especially if the stove has not been used for a long time.
• Soot build-up in the flue can ignite due to incomplete burning or failure to sweep.

Actions in case of a chimney fire:

1. Close the ash box, stove door, and damper plate (if installed).
2. Contact local fire authority.
3. Do not extinguish fire with water.
4. After a soot fire, a chimney sweeper must inspect the stove and flue before reuse.

2.8. Troubleshooting

No draught in flue; smoke enters sauna

• Leaks in flue connection: Seal the connection (see 3.2.2.).
• Cold brick flue.
• Low pressure from extractor fan or other devices: Ensure sufficient air compensation.
• Multiple fireplaces used simultaneously: Ensure sufficient air compensation.
• Full ash box.
• Blocked smoke canals (see 2.7.).
• Flue connection pipe too deep in chimney (see 3.2.2.).

Sauna does not heat up

• Sauna too large for stove's heating capacity (see Table 1).
• Many non-insulated wall surfaces in the sauna (see 1.).
• Moist or low-quality burning material (see 2.3.).
• Poor flue draught.
• Blocked smoke canals (see 2.7.).

Stove stones do not heat up

• Sauna too small for stove's heating capacity (see 1.).
• Poor flue draught.
• Moist or low-quality burning material (see 2.3.).
• Blocked smoke canals (see 2.7.).
• Check stone placement (see 2.4.). Remove small pieces and stones less than 10 cm diameter. Replace disintegrated stones with large, undamaged ones.

Stove emits smell

• See section 2.2.
• Hot stove may emphasize odors mixed in the air not caused by the sauna or stove (e.g., paint, glue, oil, seasoning).

Wooden surfaces of sauna room blacken

It is normal for wooden surfaces to blacken over time. This can be accelerated by sunlight, stove heat, wall protective agents with poor heat resistance, fine particles from stones rising with airflow, and smoke entering the sauna during refueling.

3. Instructions for Installation

3.1. Before Installation

Ensure all safety distance requirements are met. No electrical devices, wires, or flammable materials should be within the established safety distances.

• Comply with all local regulations, including national and European standards.
• The stove is not suitable for installation in a shared flue system.
• Local fire authorities can provide detailed information on fire safety regulations.

3.1.1. Ventilation of the Sauna Room

Ventilation should be arranged as follows:

Gravity Exhaust Ventilation

A. Fresh air inlet near the floor close to the stove. B. Outlet as far as possible from the stove and near the ceiling. The stove circulates air; the outlet primarily removes moisture after bathing.

Figure 4: Gravity exhaust ventilation diagram.

Mechanical Exhaust Ventilation

A. Fresh air inlet approx. 500 mm above the stove. B. Outlet close to the floor, e.g., below the bench.

Figure 5: Mechanical exhaust ventilation diagram.

3.1.2. Protecting the Floor

Figure 6: Floor protection dimensions.

• A. Concrete floor without tiles: If concrete is at least 60 mm thick, no specific safety measures are needed. Ensure no wires or water pipes are in the concrete below the stove.
• B. Tile floor: Floor glues, plasters, and waterproofing materials may not withstand heat radiation. Protect the floor with Harvia protective bedding (see 3.4.) or similar.
• C. Floor made of inflammable material: Protect with Harvia protective bedding (see 3.4.). If the floor in front of the stove door is inflammable, install non-flammable floor protection.

The stove must be installed on a floor with adequate load-bearing capacity. If not, take measures (e.g., load distributing plate).

Light-colored floor materials will get dirty from ash, stone particles, and metal flakes. Use dark floor coverings and joint grouts.

3.1.3. Safety Distances

Refer to Figures 7 and 8 for safety distances.

• Ceiling: Minimum safety distance (A).
• Walls and benches (inflammable materials): Minimum safety distances: sides (B), behind (C), in front (D).
• Masonry walls (E): Leave 50 mm between stove and walls if air can circulate in front and to one side. If the stove is recessed, leave 100 mm for air circulation.

Figure 7: Safety distances (dimensions in millimeters).

Figure 8: Safety distances with protective sheaths (dimensions in millimeters).

3.2. Installing the Stove

3.2.1. Adjustable Legs

(Excluding models M1/M2/M3/M3 SL/Linear 16/16) Adjustable legs allow firm installation on inclined floors (0–30 mm adjustment range). Unscrew feet to allow adjustment with a wrench (17 mm) when the stove is in position. Be careful, as adjustable feet can scratch the floor if the stove is moved.

3.2.2. Connecting the Stove to a Masonry Flue

Make an opening in the fireproof wall for the flue connection. The opening should be slightly larger than the flue pipe (approx. 10 mm gap). Round inner corners for free gas flow. Additional accessories are available (see 3.4.).

Connecting via Rear Opening (Figure 9)

For models M1, M2, M3/SL, 20 Pro/SL, 20 ES Pro/S, 20 Boiler/SL, Classic 140/220/280, Premium/VS, 20 RS/LS Pro, Linear 16/22/28, Linear 22 RS/LS/ES, 16/22:

1. Bend cover hatch downwards (M1/M2/M3, Classic 140/220/280, Premium/Premium VS, Linear 16, 16 only). Attach flue connection pipe to rear opening, ensuring a tight fit.
2. Position the stove. Do not block the flue by inserting the pipe too far; shorten if necessary.
3. Seal the flue connection pipe to the wall opening using fireproof mineral wool. Ensure a tight seal.

Figure 9: Connecting the stove to a masonry flue via the rear connection opening (dimensions in millimeters).

Connecting via Upper Opening (Figure 10)

Requires an angled smoke pipe (45° or 90°, see 3.4.).

1. Open rear connection opening cover hatch (specific models). Bend holder with screwdriver.
2. Move blocking plug from upper to rear opening.
3. Bend holder with screwdriver. Turn cover hatch up and lock with screw (specific models).
4. Attach flue connection pipe to upper opening, ensuring a tight fit.
5. Position the stove. Do not block the flue by inserting the pipe too far; shorten if necessary.
6. Seal the flue connection pipe to the wall opening using fireproof mineral wool. Ensure a tight seal.

Figure 10: Connecting the stove to a masonry flue via the upper connection opening (dimensions in millimeters).

3.2.3. Connecting the Stove to a Harvia Steel Chimney

A CE-marked Harvia steel chimney can be used. Smoke pipes are stainless steel, chimney is insulated for fire safety. Smoke pipe diameter is 115 mm, outer casing 220 mm (Figure 11).

1. Open rear connection opening cover hatch (specific models). Bend holder with screwdriver.
2. Move blocking plug from upper to rear opening.
3. Bend holder with screwdriver. Turn cover hatch up and lock with screw (specific models).
4. Connect the steel chimney's smoke pipe to the stove's upper connection opening, ensuring a tight fit. Refer to the steel chimney's installation instructions for details.

If a protective cover is used, the chimney insulation must start at the same level or below the cover's top surface.

Figure 11: Connecting the stove to a Harvia steel chimney (dimensions in millimeters).

3.3. Changing the Opening Direction of the Stove Door

The firing chamber door can be installed to open either to the right or to the left (Figure 12).

Figure 12: Changing the opening direction of the stove door.

3.4. Accessories

Various accessories are available to aid installation and enhance functionality:

• A. Harvia steel chimney WHP1500.
• B. Water heater VL22l: Installed on the upper connection opening. Use a radiation cover if the protective sheath is insufficient.
• C. Radiation cover WZ020130: For around the smoke pipe.
• D. Harvia protective sheath WX017.
• E. Harvia protective sheath WL400–WL775.
• F. Harvia protective bedding WX018, WL100 (not for specific models: 20 RS/LS Pro, 36, 36 Duo, Premium VS, Linear 22 RS/LS).
• G. Harvia protective bedding WL110 (not for specific models: 20 ES Pro/S, Linear 22 ES).
• H. Angle smoke pipe (various models).
• I. Lead-through flange for smoke pipe WZ020115: Covers flue opening edges and wall seals. Stainless steel, two-part.
• J. Masonry connector WZ011115: Connects to flue opening, requires no other seals; has an internal seal.

Figure 13: Accessories (dimensions in millimeters).

Serial Number: Copy the stove's serial number from the carton and attach the manual to the house documentation.