Solid fuel boilers are often chosen for cheap operation. Producers of central heating boilers determine which fuel is basic for a given boiler. If we use this fuel, we will be able to use the full power of a given device.
In top combustion boilers, the glow and flue gases spread upwards because the combustion chamber is the loading chamber and the heat needed for combustion is supplied from below. As a result, the fuel glows quickly and the boilers reach their maximum output in a short period of time. It should be remembered that we will have to add coal to this type of boilers on a regular basis in order to maintain the temperature and clean from ashes. In this type of furnaces it is difficult to monitor the amount of heat produced, which affects their efficiency. However, this is one of the cheaper boilers.
They are less popular than upper-burning boilers, mainly due to their higher price. Combustion takes place in a separate combustion chamber or in a chute chamber, which is located in the lower or rear part of the chute chamber. Boilers of this type consume less fuel because only a small part of the fuel is burned, which is located in the lower part of the charging chamber. In addition, there is a possibility of afterburning the fumes. Lower-burning boilers do not require such frequent fuel refilling. Cleanliness and efficiency achieved in bottom combustion boilers brings it closer to central heating furnaces with a feeder.
These are mainly retort boilers, in which the grate is replaced by a special burner. The fuel in the tank is replenished every few or several days. They have built-in electronic controllers, which on the basis of data from sensors, regulate the work of the fuel feeder. Thanks to this, the boiler operation output changes smoothly, which is adjusted to changes in heat demand. The prices of coal pea boilers are slightly lower than those of pellet boilers.