These instructions are designed to give you basic information about the structure and building stages of a sauna. In these instructions, the sauna is built into a ready-made room with walls made of concrete blocks and a tiled floor. The ventilation system is mechanical. The walls are panelled throughout in order to keep the heater power at a moderate level. However, a glass door is installed – when determining the right heater power level, the door must be taken into account as 1.5 m3 of additional room volume.

Planning Stage

Requirements Set By The Heater

• Carefully read the heater installation instructions, especially the safety distances. No combustible materials may be located inside the indicated safety distances. Not adhering to the safety distances causes a fire hazard. The safety distances of a wood-heated stove can be reduced with a protective sheath (see the stove installation instructions).
• If the electric heater features an external sensor, you must be able to place it precisely as prescribed in the installation instructions.
• If you have chosen a Combi heater with a steamer, the sauna room must have a floor drain. If you choose a Combi model with automated water dispensing, there must be a water supply near the heater. Furthermore, when planning the electrical wiring, it must be taken into consideration that Combi heaters are always controlled with a separate control panel.

Cables

Familiarise yourself with the wiring required by the lights, the heater and the control panel or unit and decide whether you want to have the cables under or on the panelling boards.

Sauna Decoration

• These instructions describe the installation of straight Formula benches. Harvia offers a wide selection of bench models.
• Note that the bench supports require reinforcements in the walls. The locations of the supports depend on the chosen bench model.

Floor And Ventilation

Floor

Waterproof the floor in accordance with building regulations. When selecting the flooring material, note that water thrown onto the heater washes off eroded stone that may stain white materials. Therefore, we recommend choosing a dark flooring. Pillar heaters must always be installed onto a non-combustible floor, as hot stone fragments may fall through the steel frame.

The flooring material must also cover 10–20 cm (3.93" - 7.87") of the walls. You can attach the material either directly onto the wall or onto plywood attached to the wall.

Ventilation 

A. Placement of the supply air vent. If mechanical exhaust ventilation is used, place the supply air vent above the heater. If gravity exhaust ventilation is used, place the supply air vent below or next to the heater. The diameter of the supply air pipe must be 50–100 mm.

Heaters with a separate temperature sensor: the supply air vent of the sauna must not be near the temperature sensor!

B. Exhaust air vent. Place the exhaust air vent near the floor, as far away from the heater as possible. The diameter of the exhaust air pipe should be twice the diameter of the supply air pipe. If the exhaust air vent is in the washroom, the gap underneath the sauna door must be at least 100 mm(3.93"). Mechanical exhaust ventilation must therefore be used.

C. Optional vent for drying (closed during heating and bathing). The sauna can also be dried by leaving the door open after bathing.

Framing 

• Attach framing studs (50 x 50 mm) to the walls. Space the studs by 600 mm (23.62") or in accordance with the width of the insulation material.
• Attach the ceiling frames to the wall frames. The room height of a sauna is typically 2,100–2,300 mm. The minimum height depends on the heater. The distance between the upper bench and the ceiling should not exceed 1,200 mm (47.24").

Heat Insulation 

Set the insulation materials between the framing studs. Make sure that there are no gaps in the insulation. The ceiling insulation is a particularly significant factor in energy efficiency, so install a double insulation (at least 100 mm / 3.93") to the ceiling.

Humidity Proofing (Aluminium Foil)

The purpose of aluminium foil used as humidity proofing is to keep the humidity inside the sauna. The humidity proofing must be sealed throughout in order to prevent humidity from entering the structures. The aluminium foil is attached sparsely with staples, for example. Set the shiny side of the foil towards the sauna interior.

• First, attach the aluminium foil to the ceiling and fold the edges onto the walls, so that the ceiling and wall foils overlap well. Tape the seams carefully with aluminium tape.
• Install the aluminium foil onto the walls and tape the seams. We do not recommend placing seams in corners, as this makes the taping more difficult.
• Tape the lower edges of the aluminium foil onto the upper edge of the floor tiling or onto the waterproofing.
• Tape all feed-through openings so that they are sealed!

Nailing Battens, Bench Supports And Heater Support 

• Attach nailing battens (e.g. 22 x 50 mm) onto the ceiling where the framing studs are placed.
• Attach battens onto the walls. Measure the battens so that the upper ends are approximately 20 mm (0.78") below the ceiling battens. The battens must be installed vertically to allow air to travel up from the bottom behind the panelling boards. If you wish to install the panelling boards vertically, install another set of battens horizontally onto the vertical battens.
• Check the bench heights from your bench plan and install reinforcements into the planned locations on the bench support attachments. Build the reinforcements from wood that matches the thickness of the nailing battens. The width can be 90 mm(3.54"), for example. Attach the reinforcements to the frame.
• If you have chosen a wall-mounted heater, install a support (A) onto the wall for the heater mounting screws. The support can be made of plywood, for example. See the heater’s instruction manual for the locations of the mounting screws.
• Make sure that the cables are taken into consideration. (See section 1. Planning stage.)

Panelling Boards 

• Nail the panelling boards onto the nailing battens. Begin from the ceiling.
• Nail a few rows of panelling boards onto one wall and then move on to the next wall. By going around like this, you can make sure that any width differences in the panelling boards do not affect the end result.
• Drill holes for the electrical wires into the boards where needed, and insert the wires through the holes.
• Leave an air gap of a few millimetres between the upper edge of the panelling boards and the ceiling.

Finishing The Interior Surface 

Attach the air vents.

Bench Supports And Light 

Install the bench supports in accordance with the bench plan. We recommend installing the light at this stage (if necessary, turn to a professional electrical engineer).

Benches 

Lift the benches onto the bench supports. Follow the installation instructions supplied with the benches.

Heater 

Install and connect the heater in accordance with the installation instructions.

1. If you have selected a wall-mounted heater, there needs to be a supporting structure for it behind the panelling boards. The mounting screws will not hold on panelling boards alone and the heater may fall onto the floor. In practice, sturdy boards for the mounting screws or a similar solution will suffice as a supporting structure. See the heater’s instruction manual for the locations of the mounting screws.

2. Familiarise yourself with the wiring required by the lights, the heater and the control unit (if one is used) and decide whether you want to have the cables under or on the panelling boards.

• A. Wires for the temperature and/or humidity sensors of the heater
• B. Electrical wiring for the heater
• C. Wiring for the sauna lights
• D. Any other wiring (special lights etc.)

3. Note that the benches require supports on the walls. There must be sturdy supporting structures behind the panelling boards for the bench supports.

Sauna With An Electric Heater

The air in the sauna should change six times per hour.

A. Placement of the supply air vent. If mechanical exhaust ventilation is used, place the supply air vent above the heater. If gravity exhaust ventilation is used, place the supply air vent below or next to the heater. The diameter of the supply air pipe must be 50–100 mm. Heaters with a separate temperature sensor: the supply air vent of the sauna must not be near the temperature sensor! For more detailed instructions, see the heater installation instructions.

B. Exhaust air vent. Place the exhaust air vent near the floor, as far away from the heater as possible. The diameter of the exhaust air pipe should be twice the diameter of the supply air pipe.

C. Optional vent for drying (closed during heating and bathing). The sauna can also be dried by leaving the door open after bathing.

D. If the exhaust air vent is in the washroom, the gap underneath the sauna door must be at least 100 mm (3.93"). Mechanical exhaust ventilation must be used.

Sauna With a Wood-heated Stove

Gravity Ventilation

A. The fresh air inlet must be placed close to the floor near the stove and

B. its outlet should be as far away from the stove as possible, and near the roof. The stove itself circulates air effectively; the purpose of the outlet is mainly to remove humidity from the sauna after bathing.

A. The fresh air inlet must be approx. 500 mm (19.68") above the stove and

B. the outlet should be close to the floor, e.g. under the benches.

The volume and structures of the sauna affect the selection of heater power. An average of 1 kW of heater power is required for each cubic metre of sauna volume. The power requirement increases if there are window surfaces or heat-storing surfaces such as brick, concrete or massive logs in the sauna.

One square metre of stone, glass or similar non-insulated surface increases the heater power requirement as much as if the sauna room volume were increased by 1.2 cubic metres. If the interior walls of the sauna room are made of non-insulated logs, the corresponding factor is 1.5.

If the heating capacity is too small, the heater needs to be heated longer and more intensely, which reduces its life span.

External control units are necessary for large heaters used in public facilities, but they are also well-suited for home use as long as the required electrical and sensor wiring is taken into account when planning the sauna.

Many heaters intended for home use are also available as so-called E models that utilise a control unit instead of operating switches on the heater. This is especially convenient when the heater is embedded into a bench.

The volume and structures of the sauna affect the selection of heater power. An average of 1 kW of heater power is required for each cubic metre of sauna volume. The power requirement increases if there are window surfaces or heat-storing surfaces such as brick, concrete or massive logs in the sauna.

One square metre of stone, glass or similar non-insulated surface increases the heater power requirement as much as if the sauna room volume were increased by 1.2 cubic metres. If the interior walls of the sauna room are made of non-insulated logs, the corresponding factor is 1.5.

If the heating capacity is too small, the heater needs to be heated longer and more intensely, which reduces its life span.

External control units are necessary for large heaters used in public facilities, but they are also well-suited for home use as long as the required electrical and sensor wiring is taken into account when planning the sauna.

Many heaters intended for home use are also available as so-called E models that utilise a control unit instead of operating switches on the heater. This is especially convenient when the heater is embedded into a bench.

All electrical appliances that are fitted with a protective housing, that is attached by screws to prevent dangerous live components from coming into contact with one another, must be installed and serviced, in compliance with the regulations in place, by a professional, authorised electrical engineer or any such other knowledgeable person.

All electrical appliances that are fitted with a protective housing that is attached by screws to prevent dangerous live components from coming into contact with one another must be installed and serviced, in compliance with the regulations in place, by a professional, authorised electrical engineer or any such other knowledgeable person.

A connection cable between the junction box on the sauna wall and the terminal strip of the heater is not supplied with the heater. The electrical engineer who connects the heater will supply the cable. The information of the connection cable can be found in the installation instructions of the heater and/or control unit.

The control panel is splash-proof and has a low voltage. It can be installed in the washroom, the dressing room or the living area, for example. If the control panel is installed in the sauna, it should be placed no closer than the minimum safety distance from the heater and no higher than one metre from the floor. Keep out of reach of children.

The sauna must always be checked before the heater is turned on. This is to make sure that no combustible objects are left near or on the heater. If you wish to have your sauna ready quickly, we recommend a heat-storing Forte heater.

A fault current protector must not be installed into the heater’s electrical circuit, as the heater is sufficiently protected when earthed. Fault current protectors are designed to ensure the safety of small electrical appliances, such as a coffee maker.

The silicone cable supplied with the sensor can withstand temperatures up to 170°C (338°F). The cable can be extended with a lower temperature value cable with an equivalent cross section, provided that the temperature affecting the cable after the connection does not exceed 80°C (176°F).

Please note! The supply air vent of the sauna must not be near the temperature sensor.The air stream near the vent will cool the sensor, resulting in the sensor sending erroneous temperature information to the control unit. This may cause the heater to overheat. Minimum distance between the supply air vent and the temperature sensor:

• non-directional vent: 1,000 mm (39.3")
• vent directed away from the sensor: 500 mm (19.6")

Even the smallest wood-heated stoves are equal to a 13 kW heater in terms of heating power. If you wish to install an electric heater to accompany a wood-heated stove in your sauna, the power of the heater must be selected carefully in accordance with the directions provided by the factory.

Safety Distances Of The Heater And The Stove To Combustible Materials

The safety distance requirements for both the heater and the stove must be met. See the installation instructions of the heater and the stove for the safety distance requirements.

Safety Distance Between The Heater And The Stove

The distance between the heater and the stove must be their respective safety distances combined, however no less than 600 mm(23.6"). This safety distance can be reduced with a protective sheath for the wood-heated stove.

Water thrown on the heater cools the stones quickly.

• Make sure that the fuses/breakers of the heater on the electrical panel are in working order. Please note that there are one to three fuses/breakers on the electrical panel, depending on the heater model and electricity system.

• Check that all the heating elements are glowing when the heater is on.

• Set a higher temperature.

• Make sure that the heater is sufficiently powerful.

• Check the heater stones. If the stones are stacked too tightly, compacted over time or the wrong kind, air circulation in the heater may be blocked, which in turn decreases the heating power.

• Make sure that the ventilation of the sauna is arranged correctly.

• Test whether the thermostat works correctly:

1. Remove stones from the heater until you can see the ends of all heating elements.

2. Turn the heater on. The heating elements will begin to glow. If a heating element does not glow, it must be replaced. Remember to close the sauna door.

3. Monitor when the heating elements turn off. This happens when the sauna temperature has reached the desired temperature set with the thermostat. Usually, the desired temperature will be reached in 35–45 minutes from turning on the heater. If it takes significantly longer to reach the desired temperature, the temperature sensor may be placed incorrectly, the heater may not have enough power, or the thermostat may be faulty.

Check the data cable and its connections.

Water thrown onto the heater does not vaporise and runs through the stone compartment.

• Set a lower temperature.
• Make sure that the heater is not too powerful.
• Make sure that the ventilation of the sauna is arranged correctly.

• Make sure that the safety distance requirements are met.
• Check the heater stones. If the stones are stacked too tightly, compacted over time or the wrong kind, air circulation in the heater may be blocked, which can cause overheating in the structures (especially when an electric heater is used).
• It is perfectly normal for the wooden surfaces of the sauna to darken over time. The darkening may be accelerated by
  – sunlight
  – heat from the heater
  – protective agents on the walls (protective agents have a poor heat resistance level)
  – fine particles coming off the heater stones and lifted by the air flow
• Wood-heated saunas: smoke that enters the sauna when adding firewood, for example

• If the heater is new, it may still have residual protective agents from the manufacturing process. Carry out the first heating in a well-ventilated room.
• The hot heater may emphasise smells mixed in the air that are not, however, caused by the sauna or the heater. Examples: paint, glue, heating oil, spices.

• The timer switch is a mechanical device that emits a ticking sound when working normally. If you hear ticking even though the heater is off, check the connections of the timer switch.
• Occasional bangs are usually caused by stones splitting due to the heat.
• Thermal expansion in the heater parts may cause sounds when the heater is heating up.

Remember to always check the sauna before heating. No unwanted objects must be left on or near the heater. Never dry your laundry in the sauna.

The heater is on standby when the backlight of the I/O button is on. If the backlight is off, make sure that the heater has been turned on with the main power switch at the bottom of the heater.

Turning The Heater On Immediately

	1. Turn the heater on by pressing the I/O button on the control panel. The control panel will light up and the heater will begin to heat up immediately.
	2. If necessary, adjust the temperature with the + and – buttons.

After bathing, turn the heater off by pressing the I/O button.

1. Turn the heater on by pressing the I/O button on the control panel.

2. Press the MENU button twice. This enters a mode where you can change the remaining on-time.

3. Press the + button. The heater will turn off and the timer indicator light will begin to flash. The panel shows the time after which the heating will begin. The time may be pre-set at 10-minute intervals up to 10 hours and at one-hour intervals from 10 to 18 hours.

4. Press the MENU button and wait for the control panel to return to the default mode. Please note that the time shown on the panel will also count down at the aforementioned intervals.

Heater stones should be of a material that is as heavy as possible, dark in colour and large in size for them to be able to store as much heat energy as possible. Heater dealers sell stones that are specifically intended for use as heater stones, and that come from well-known suppliers, so their composition and suitability are guaranteed. Stone materials suitable for heater use include peridotite, olivine and olivine diabase. Surface rocks collected in nature are not suitable for heater use.

Ceramic “stones” and soft soapstones must not be used. They do not store enough heat when heating up the heater. This may result in the heater overheating, which in turn leads to the heating elements breaking.

The heater stones must be stacked in the heater in accordance with the installation and user instructions of the heater. Heater stones are available in two sizes.

How often they are changed by and large depends on how much the heater is used. If it is an average of twice a week, the stones should be changed once a year. The stones should be restacked at times, as they will crumble in use and compact in the stone compartment, reducing the air circulation. Good air circulation guarantees a proper sauna experience. The heating elements will also last longer with good air circulation.