In heating only mode, the puffer stores the excess hot water produced by the stove and releases it to the radiators when needed. With the extremely cost-effective result of having heating that works even when the stove is turned off.
Also in the case of heating and domestic hot water production, a large amount of hot water produced by the stove is always available, instantly and whenever you need it, even when the stove is turned off.
When is it required or strongly recommended
If there are solar panels, the hot water produced must be stored somewhere to be used when it is needed.
If the underfloor heating system is to be powered by the stove instead of radiators, a buffer tank is practically obligatory. The water produced by the stove reaches 70-80°C, a temperature that is good for radiators, but not for the underfloor heating system, which does not exceed 30°C. Without the buffer, the excess energy would be lost to cool the water, whereas with the buffer it is simply stored and mixed with cold water until it reaches the required temperature.
Puffer sizing
The size of the puffer depends on what it will be used for, in addition to the space available. In general, a puffer should have a minimum capacity of 20 liters/kW for a pellet burning product and 50 liters/kW for a wood burning product.