1. Circulation system - open or closed?
In case You have an open circulation system, You have to mount an open expansion vessel at the highest point of the installation. The vessel should be chosen according to the total amount of water that the central heating system contains (approximately 5% of the total amount). An example of the vessel mounting scheme is shown above.
If You have a closed circulation system, You can use our boilers as well. In this system a closed pressurised expansion vessel is used (approximately 12% of the total amount). The installation always needs to be secured by using one or two safety valves. We recommend a 1,5bar safety valve bar for boilers up to 65 kW, and a 2 bar for boilers above 65kW.
To protect the boiler and the closed installation from boiling there is a need to install a cooling device. There are two solutions:
a) Cooling circuit with an One-way valve (cools down the whole installation when the temperature rises above 97 centigrades Celsius).
In some boilers, such a cooling circuit is built-in into the boiler, e.g. Atmos, Orlan Super.
In some boilers it is available for an extra fee:
Dakon Dor , Ogniwo 12,6-20kW.
In other steel boilers and in all cast-iron boilers you need to mount a cooling circuit as an additional element. Do not forget to order the cooling loop together with the One-way thermal release valve e.g. Danfoss BVTS, Watts STS-20.
b) Two-way thermal release valve e.g. Regulus DBV-1, Syr 5067 or Caleffi 544 (pours cold water into the water return and releases hot water from the hot water supply at the same time). This solution is used mainly for bigger boilers, e.g. with a power above 50kW, because in these cases an external cooling loop might not be enough for cooling down the boiler. It is important that the sensor of this valve is in contact with the moving hot water from the hot water supply so that it really switches on at 95-97 degrees Celsius.
To guarantee the correct fuel burning boilers are equipped with an automatic aeration device:
Draught regulator – mechanically lifts up the lower air inlet door depending on wanted temperature,
Ventilator – blows air into the combustion chamber, it is used with a steering.
These additional devices are sometimes already included in the Price, sometimes they must be bought separately. If You click on a boiler, than scroll down to the bottom of the product description, there You find the available options.
3. Boiler with an automatic fuel supplier
If you like comfort and can afford it, a boiler with an automatic fuel supply is a good solution. Such a boiler has very often a retort burner which is feeded with the essential amount of fuel needed to achieve the required water temperature. The aeration is processed automatically, so the exhaust gases are clean. All you have to do is filling the hopper (in average every 3–10 days). The hopper can be mounted on the right or on the left side of the boiler depending on the needs. These boilers are used also in summer for domestic hot water heating. For burning coal 5–25 mm screw feeders are used, whilst for fine coal are used piston ones.
4. Mixing valves
You can use a three-way mixing valve. It is mounted at the return. Its function is to protect the boiler from corrosion and tar formation by heating up water returning to it. The three-way mixing valve can be regulated manually or it can be a thermostatic one. A thermostatic three-way mixing valve works automatically.
Ports 1 and 3 are always open, which allows circulation in boiler network as well as a higher return temperature to the network. Port 2 opens with increase of water temperature. See photo below:
Another option is a four-way mixing valve. It protects the boiler as well as the former one. Additionally, it can keep a lower temperature in radiators at the same time. Such a four-way valve leads some of the hot water exiting the boiler to the boiler again. This heating up of the return water protects the boiler from low temperature corrosion and prolongs the boiler exploitation. The same quantity of water returning from radiators the mixing valve leads again to them. This enables the boiler to work with the suggested temperature at least 60oC and keeping of a lower temperature in the radiators at the same time.
5. Ceramic and cast iron parts, Sealing cords, Insulations are operating elements and they are not under warranty subjects.