Dimensioning of steam generator
The steam generator power is chosen according to Harvia’s instructions to correspond to the installation environment. Choosing a steam generator that is too powerful speeds up the heating period, but reduces the amount of visible steam in the steam room when used for longer periods. In an ideal situation, the steam generator’s output power and the heat exiting the room are in balance.
Refer to the Harvia steam generators’ manual to assess the suitable power of a steam generator for your steam room.
The installation location of a steam generator
The steam generator is installed in a dry location that has a floor drain or equivalent outlet to the drain, and sufficient ventilation.
We recommend that you install the steam generator at the same level as the steam room, preferably less than 6 meters, and definitely no further than 10 meters, from the steam room. If the distance is more than 10 meters, the steam pipe diameter must be greater. By increasing the pipe diameter, you reduce the flow resistance.
Water inlet for the steam generator
The water inlet must have a shut-off valve. The water inlet must be a flexible, steel-reinforced hose with a ¾” threaded coupling. By using a flexible hose, you reduce the effect of pressure surges on the water connection. A flexible hose enables a variety of installations in confined spaces or if installation is otherwise difficult. Only cold tap water should be fed into the steam generator. The water pressure and flow rate must meet the product manufacturer's specifications
Steam pipe dimensions
The steam pipe dimensions are determined by the equipment supplier’s instructions. If the steam generator power is <10 kW, cu22 mm; 10...20 kW, cu28; >20 kW, cu35 mm. the steam pipe may not have 90-degree angles with a small radius, minimum of R75 from the center line of the pipe.
The steam pipe material can be copper used for hot-water piping or acid-resistant stainless steel.
The steam pipe lead-through must be insulated with, for example, Armaflex pipe insulation, which has a continuous thermal resistance of 145 °C. The lead-through point must be made watertight to prevent humidity from entering the building structures. A lead-through flange can be used for the insulation, sealed against the tiles with a sealant that has a thermal resistance of at least 145 °C.
The steam pipe must descend the entire distance from the steam generator to the steam room, and there may not be any horizontal sections, as water will condense in such. However, if the pipe must be run from the steam generator to the steam nozzle through, for example, the ceiling, the steam pipe must ride to its highest point right after the steam generator, and then descend all the way to the steam nozzle.
The steam pipe is insulated with, for example, an Armaflex pipe insulator or equivalent product that has a continuous thermal resistance of at least 145 °C. If the beginning of the steam pipe goes upwards, the fragrance pump connection must be located so that the fragrance liquid will not flow along the steam pipe into the steam generator.
Connecting the fragrance pump into the steam pipe
The fragrance pump’s fragrance liquid pipe is connected to the steam pipe using the product manufacturer’s parts, and the correct location for this is near the steam pipe outlet.
Water purification solutions
Using clean water is important to both the users of the sauna and spa, and to the equipment generating the steam. The high content of calcium, magnesium, lime, or other minerals in water is not suitable for steam generators in the long term. If steam generators are exposed to such minerals for long periods, the water tank or heating elements may be damaged, and may also result in unpleasant smells in the steam room. We recommend that you use a water purifier or softener with a steam generator to extend the service life of your steam generator.
For the best experience, we recommend using one of the official Harvia steam nozzles, for example, the Silent steam nozzle. If space is not a problem, we recommend that you use a separate steam well instead of a steam nozzle. If the steam pipe outlet is below the foot level under the benches, the nozzle can be connected to an acid-resistant stainless steel pipe with a diameter of 42 mm. Holes with a diameter of 8 mm are drilled into the pipe approximately every 300 mm, with the holes pointing toward the floor. The pipe must have a clearance of about 150 mm between the top part of the embedded section and the floor.
Steam room lighting
A steam room can be lit with Harvia fiber optic lights. Fiber optic lights are installed on the steam room ceiling to light up the steam room and/or on the front side of the benches to light up the floor so that people see where the floor ends and benches begin, and where there’s room to sit. Other lighting solutions may also be used, but the suitability of each lighting type for humid environments must be ensured (IP65). In-home use, we recommended that you also include a separate light when cleaning the steam room (this is mandatory in public steam rooms).
Steam room structure
A steam room may be built with Harvia Spa Modules, insulated plates or with masonry. A steam room must have a floor drain or the floor must have a gradient in the entire room, leading to the doorway of the adjoining room that has a floor drain. The steam room structure and materials affect the steam generator power and its dimensioning. See the dimensioning instructions.
We recommended that the steam room interior is made waterproof throughout. Please observe the local water insulation regulations. Follow the waterproofing material manufacturer’s instructions. All waterproofing materials should have a thermal resistance of 80 °C.
Normal bathroom tiles can be used in steam rooms, but porous natural store materials should be avoided, or at least realizing that they have a tendency of becoming eroded. Steam absorbed by porous surface materials will shorten their service life.
Steam room tiles can be fitted with a cementitious adhesive that can withstand a temperature of 80 °C.
In-home steam rooms, normal tile sealants can be used, but we recommend those containing epoxy. In public steam rooms, the tile sealant must be epoxy-based. Normal tile sealants are porous, which is not strong enough in public steam rooms owing to heavier use, and will start crumbling.
No organic building materials, such as wood, may be used inside steam rooms.
Steam room ceiling
The steam room ceiling must be curved or mono-pitch with an angle of at least 15 degrees. It can also be pitched in shape. Small tiles in the ceiling increase condensation and the creation of drops.
Steam room benches
Steam room benches can be placed on one or more levels. The benches must be sloping so that condensed water is allowed to flow off them. If ergonomic bench profiles are used, water is removed from recesses with tubes or water grooves. Steam room benches can be equipped with heating or cooling. Heating can be done with an embedded heating cable, heating element, or water-circulating pipes. The heating must be equipped with a separate thermostat and the heating system must be dimensioned so that the temperature on the benches never rises above 50 °C.
Steam room door
The steam room door should be 8mm tempered glass, or 8mm double-layer laminated and tempered glass or polycarbonate (PC) plastic. The door frames are made of aluminum or acid-resistant stainless steel plates. The door hinges are made of acid-resistant stainless steel or some other material that can withstand continuous humidity. The door handles are made of plastic, steel, or aluminum. We recommend that you have insulation on the door and a gap of about 15 mm between the bottom edge of the door and the floor.
Steam room ventilation
Steam rooms in private homes are not required to have separate ventilation, provided the adjoining wet room has a mechanical supply and exhaust ventilation. However, mechanical supply and exhaust ventilation is recommended for a steam room. The recommended material for supply and exhaust ventilation ducts is plastic. The suitability of the ventilation system must be checked with the ventilation system manufacturer or a qualified professional. When using mechanical ventilation, the fresh air duct should be as close to the steam nozzle as possible, or at floor level when using steam well. The exhaust air vent is placed on the opposite wall of the fresh air duct, on the wall, approx. 500 mm from the ceiling. The ventilation is adjusted to be at negative pressure, and the volume of air to be replaced can be the same design values as in a normal sauna. (3–7 l/s/m²). In public steam rooms, mechanical ventilation is mandatory.
Steam room temperature control
A temperature sensor is installed in a steam room at the height of approx. 1600 mm and a minimum distance of 500 mm from the air supply vent. The temperature sensor’s lead-through is sealed with a suitable sealant. A hole with a diameter of 8 mm is drilled for the Harvia temperature sensor, with the sensor embedded into the tile so that about 5 mm remains visible in the steam room. The ideal temperature of a steam room should be between 45–50 °C.
Steam Generator System Components
1. Control panel
2. Temperature sensor
3. Steam pipe
4. Steam nozzle
5. Water supply pipe
6. Water supply pipe valve
7. Discharge water pipe
8a. Manual discharge valve
8b. Automatic discharge valve (optional)
9. Floor drain
10. Overpressure valve
11. Connection cable
12. Fragrance pump (optional)
13. Sediment cup