How to choose a stove or insert correctly

The decisive factor is the output, not the design

The primary goal is to choose a pellet stove or fireplace insert with an appropriate output to match the thermal losses of the heated space. Once such a stove reaches the required temperature of the heated space, it must be damped by significant restriction of the combustion air. This results in imperfect combustion and increased CO content in the combustion products, causing the glass of the stove door to become dirty, greater sedimentation in the flue gas ducting, and uneconomic operation of the stove.

The stove output range that we specify (33–100%) will be reached assuming that the fuel is adequately dry (moisture content of up to 20%). The actual required output of the fireplace insert can be set objectively on the basis of the calculation of heat losses of the heated space. Based on this calculation, it is possible to choose the appropriate type of fireplace stove, pellet stove, or fireplace insert, taking into consideration the stove output figure. A rough calculation of the heated space is ascertained by computing the heated space volume (height x width x length). HAAS+SOHN Rukov bases its conversion to kW on the average heat losses in the Czech Republic, which are equivalent to approximately 1 kW = 18 m3.

The final stage is choosing a suitable design of the stove, fireplace insert, or fireplace stove kit.

Central air supply and tertiary combustion for higher quality combustion

External air supply is currently a highly sought-after technical solution for supplying combustion air to stoves and inserts. It is sometimes also termed the central air supply (CAS). Stoves or fireplace inserts using this technology are suitable mainly for newly renovated houses and low energy or passive buildings. An ideal set of solutions are products marked as RLU (for instance, Ovalis RLU), which are specially tested for gas-tightness. The most frequent source of combustion air is the hole in the rear section of the fireplace stove or tile stove. In the case of fireplace stoves and inserts made by HAAS+SOHN Rukov, the mouth diameter is 100 mm, and for pellet stoves 60 mm. After connecting the ducting, the air is sucked in from the exterior. The oxygen in the dwelling space where the fireplace stove, pellet stove, fireplace insert or fireplace stove kit has been installed is thus not consumed.

The output of the heater is also significantly influenced by tertiary (dual) combustion, which is often referred to as 'clean burning' (CB). This system uses air that is fed through channels along the combustion chamber, where it is pre-heated to a high temperature, thus facilitating higher quality combustion. This solution allows the natural supply of air to the flame at the appropriate point according to current requirements and burning stage. Its most significant function is seen in the form of 'lateral' small flames in the upper section of the combustion chamber (above the flame). The entire system increases the overall efficiency of the stove, which in the end results in lower fuel consumption.

Suitable chimney

The overall condition of the chimney is very important. HAAS+SOHN Rukov products require a minimum chimney draft of 10 or 12 Pa, while pellet stoves require 6 Pa. Any chimney sweep can ensure fulfilment of these conditions for you. Stoves or fireplace inserts must be connected to at least the same chimney diameter as that stated on the product itself. If the heater is connected to a smaller chimney diameter, an inadequate draft is created, which may for instance cause smoking during fuelling.

HAAS+SOHN Rukov recommends that fireplace stoves be connected using ducting with a maximum length of 1.5 m and one elbow!

Fireplace stoves and inserts with a hot water exchanger

Fireplace stoves, tile stoves, pellet stoves or fireplace inserts with a hot water exchanger are a suitable choice for connecting heating bodies or water heater tanks. It is also possible to connect them to an existing heating system with an electric or gas boiler. Thanks to this option, it is possible to heat the entire house and achieve significant heating cost savings during the heating season.
Some types of exchanger stoves made by HAAS+SOHN Rukov have a removable heat exchanger, which can be removed as required or otherwise added. The exchanger is capable of transferring about 47–79% of the total thermal output to the heating elements (water storage tank) depending on the type of stove or insert. The output of the exchanger in a fireplace stove with exchanger is up to 11.1 kW. A fireplace insert with exchanger can transfer up to 14.7 kW to the water system.

The total output is always stated for stoves, from which the output of the heat exchanger must be deducted to ascertain the output the stove itself can deliver to the space in which it is installed.

A prerequisite for installation of a fireplace stove with exchanger is the implementation of a project with deduction of the heat losses of the room in which radiators will be used. Assembly of the stove and the hot water installation should be done by a specialised heating company. 
'How many radiators can I connect to the exchanger?' – This is the most common question when ascertaining information. The best solution is to consult with a heating company, which will determine this on the basis of a computation of the heat losses with regard to the exchanger output. The output of the radiators must match the output of the given type of fireplace stove exchanger.

A fireplace stove with heat exchanger must be secured against electric power failure either by using a back-up power supply or a cooling loop, which can be ordered as a special accessory or is already a fixed component of certain models of stoves or fireplace inserts with heat exchangers. The cooling loop can be used only if the customer has the possibility to connect to the municipal water mains.

Fireplace stoves with heat exchanger or fireplace inserts with a higher output hot water heat exchanger additionally have passive protection against overheating in the form of automatic regulation of the primary combustion air. Upon failure of the electric power and the water temperature in the exchanger reaching 95°C, the primary air supply under the grill automatically closes, resulting in 'suffocation' of the stove.

Fireplace kits

The fireplace set casing is made of lightweight concrete and consists of individual sections. These are placed one on top of the other and fixed using acrylic adhesive, which is included in the delivery. The casing is supplied in the raw state and must be treated with primer before installation. It must dry for an adequate period of time, and then the surface may subsequently be coated and finished according to your own requirements. Maintenance is done by simple repainting.

Prior to installing the set, it is fundamentally important to verify the load capacity of the floor. The total weight of the complete set (fireplace insert with refractory lining and artificial stone lining) may – depending on the variant – range from 380 to 400 kg.

When installing a fireplace set, it is necessary to observe fire prevention regulations according to the legislation applicable to the given type of appliances in the country where it is installed. It is particularly necessary to prevent flammable walls or statically sensitive structural parts from overheating, eg reinforced concrete walls. A fire set comprising shielding plates is used for heat shielding of the fireplace insert; these plates must always be installed in case of flammable or statically sensitive walls. Fire protection can be ordered as a separate accessory.

Pellet stoves

Pellet stoves offer a very modern method of heating with fully automatic operation. The stove output is controlled on the basis of the desired temperature, which is measured by means of a sensor that monitors the room temperature. From the HSP 6 model series, you additionally have the option to set the automatic mode for one week, where you can choose up to three different time segments for each day. The special design of HAAS+SOHN pellet stoves makes extraordinarily quiet operation possible thanks to the hot-air exchanger without use of draft fans, which means the stoves are completely different from all other models. 

A revolutionary element is easy control via the HAAS+SOHN application. You can control the pellet stove using the 'LOCAL' function in the house and its vicinity, or via the 'GLOBAL' function from any point on the globe! You can enjoy your Quality times thanks to the WLAN module, which can easily be installed on the stove. 

Commissioning the pellet stove is done only by the trained staff of a specialised installation company. A list of all collaborating companies and their contact information is included in the Operating Manual.