Our electric smoke extractor has a 6-speed regulator, so you only need to set it to speeds of 1-2 to help extract smoke naturally, but not heat.
Basically, at the first two speeds, we are not altering in any way the normal operation of a fireplace, which would normally disperse a very small amount of heat in the smoke rising in the flue pipe. The Gemi chimney fan sucks up the smoke that would otherwise go into the house and therefore, certainly, would not produce any heat sources for the indoor environment.
It is clear that if the chimney fan does not operate at the sixth speed (usually at this speed it is used to change the air in rooms, to help start fires or to suck up the ashes), with its 2500m³/h(basic) - 3800m³/h(pro) it will be so powerful that it will also suck up the heat, because it will increase the speed of combustion of the wood and consequently partially reduce the heat. Scientific studies have shown that the Gemi smoke extractor can control heat loss, so it is advisable to use a chimney to prevent heat loss.
This can be seen in the millions of satisfied customers all over the world since 1983, when the first Gemi chimney fan was created.