Mondex heaters are designed to last. If you already own one, you will find instructions for use and maintenance here.
If you're planning a sauna renovation and wondering how to install a heater or what it takes to connect an electric heater or install a wood heater, you've come to the right place. In this guide, we'll tell you what you need to know before, during and after the installation to ensure your new sauna works safely and provides perfect heat for years to come.
Before installing the heater
When a sauna renovation is needed, choice of heater and installation are important steps. The size and power of the heater is always chosen according to the size and construction of the sauna, but there are also many other things to consider when installing it.
Before installation, the heater should be stored in its original packaging in a dry and warm place. For Mondex heaters, the packaging of the electric models includes the heater itself, as well as the thermostat sensor, electronic controller and the necessary cables, depending on the model. The packaging protects the heater and accessories from moisture and shocks. Before starting work, check the condition of the parts, and if you notice any defects, contact your dealer.
The sauna floor should be protected before installation to prevent damage. When the heater is placed in position, the adjustable feet can be used to fine-tune the position to make it straight and stable. If the heater is to be embedded in the ceiling, the installation of the heater is also planned in advance. An electrician will connect the wiring before the final installation and ensure that the control unit and sensors are correctly positioned.
Always leave a safety distance between the heater and the combustible material, as specified for each model. This ensures safe operation and prevents overheating of the sauna structure.
Basic principles of heater installation in stages
- Placement and platform: The heater is mounted firmly on the floor or wall. Wood-burning heaters needs a flat, non-combustible and heat-resistant substrate.
- Safety distances: Check the model-specific minimum distances and also take ventilation into account.
- Coupling or chimney connection: Electric sauna heaters connected to the mains by a professional, the wood heater is connected to the flue according to the manufacturer's instructions.
- Loading of stones: Use only heater stones with a block surface (e.g. olivine diabase). The stones should be stacked in such a way as to maintain air circulation, the outer stones in electric heaters more tightly, the inner stones more loosely. Too tight a stacking can prevent adequate air circulation and break the resistors in the electric heater. Stones are also stacked loosely in wood heaters to allow air circulation and prevent overheating of the firebox.
The wiring of an electric heater belongs to a professional
The installation of an electric heater is subject to authorisation in Finland. This means that the wiring of an electric heater can only be carried out by an electrician who has a electrical qualification certificate (S2). A professional will ensure that all regulations are met and that the installation is safe.
Incorrect wiring of the heater can cause overheating, electrical failure or, in the worst case, fire. It is therefore important to rely on a professional during the installation phase. For more information on sauna installations, visit the Tukes website. on electrical installation requirements.
The installation also takes into account the safety distances. For example, in Mondex electric shutters, the distance to the sides is usually 100-120 mm and to the top 770-1070 mm, depending on the model. These dimensions ensure that the heat is distributed correctly and that the sauna structure is not subjected to excessive heat.
In the case of a separately controlled heater, the location of the controller should be considered before installation. It can be placed in a washroom or dressing room, for example, making it easy to control the temperature in the sauna without having to go into a hot room. The dimensions of the control panel allow it to be installed directly in the light switch box.
Wood heater installation - safety first
The charm of a wood heater lies in its natural warmth and the atmosphere of the fire. But at the same time it requires careful installation and attention to detail. The most important thing is to make sure that the clearances to combustible materials and the chimney connection are correct.
The safety distances of a wood heater to combustible structures are always determined by the instructions of the heater manufacturer. Rakentaja.fisays the typical distance should be around 1000 mm at the front, 500 mm at the back and 500 mm at the sides. Mondex Klapi front 500 mm, sides and rear only 250 mm and Mondex Motti 500 mm to the front, 300 mm to the sides and rear. If a light shield is installed around the heater, these can be reduced: a single shield reduces the distances by about half and a double shield by up to 75%.
The safety distances between the top and bottom of the heater vary depending on the model. Typical distances to the upper surface are 800-1200 mm and for electric heaters at least 250 mm to the floor, unless the heater is a floor standing one. These distances can also be reduced by around 25-50% with approved fire protection. If the heater is installed on a wooden floor, a non-combustible protective underlay and sheet metal extending 400 mm in front of the heater and 100 mm to the sides must be used.
The wood heater is connected to the flue either from the top or the back. The internal diameter of the flue must be, for example, 115 mm for Mondex heaters and its draft must be at least -12 Pa. The connection is sealed with refractory mineral wool, and the flue is regularly fumigated in accordance with legal requirements. When the heater is installed, it must be heated first outdoors or in a well-ventilated area so that the substances in the surface treatment burn off. Only then can the heater be installed, filled with stones and put into operation.
Read also: Heater safety distances - these things you need to know
Good ventilation makes the sauna comfortable
The ventilation in the sauna has a big impact on both the functioning of the heater and the quality of the sauna baths. In an electric sauna, the inlet air is usually ducted at a height of about half a metre above the heater and the exhaust is placed as low as possible on the opposite wall. This ensures that the heater receives sufficient oxygen and the heat is distributed evenly.
In a sauna with a wood heater, the supply air is brought close to the heater and the exhaust duct is placed upwards, as far away from the heater as possible. This ensures that the combustion is clean and the sauna stays fresh throughout the sauna session.
Heater commissioning
Before the first heating, remove all protective plastics and ensure that the sauna stones are stacked correctly. During the initial heating, an electric heater may produce an odor and a wood‑burning heater may emit some smoke – this is normal and will dissipate quickly.
The electric heater is not intended for continuous use, but the best steam is achieved when the heating time is moderate before entering the sauna, usually 30-60 minutes depending on the size of the sauna. Check that the controller or timer automatically switches off the power after heating.
Once the installation is done correctly and the sauna is properly ventilated, the heater is ready to provide soft and safe heat for years to come.
Read also: First heating of an electric heater - a guide to safe heater commissioning
Tips for safe sauna bathing
A safe sauna is a comfortable sauna. Remember these simple but important principles:
- Never cover the heater or use it as a tumble dryer
- Children and people with reduced mobility must be supervised when taking a sauna
- Don't go to the sauna while intoxicated
- Before heating, check that there is no combustible material in the vicinity of the heater
These small things will prevent the most common sauna safety problems and extend the life of your heater.
Discover the Mondex range of heaters
Once the heater has been safely installed and connected, it's time to focus on enjoying a perfect fire.
All Mondex heaters are manufactured in Ylivieska and are also key ticket products. Mondex's range includes heaters designed for Finnish homes, combining quality, design and durability. Whether your dream is a modern electric heater for easy everyday use or a traditional wood heater with a real fire atmosphere, Mondex has a model to suit your sauna.
Discover the Mondex range of heaters here and find a sauna heater built to last, delivering the best steam year after year.
Mondex - The soul of the Finnish sauna.