Centralised replacement air heating is often the most sensible way to carry out the heating when there is high demand for replacement air due to, for example, processes that foul the air. The advantage gained by choosing a gas-based replacement air heating, is the excellent operating efficiency.The efficiency follows from the fact that, in most cases, the combustion gas can be led directly to the heated space and no separate heat exchanger is needed, unlike if the heating is e.g. oil-based.
Fingas supplies replacement air heaters from two European manufacturers. MARK GC and Combat ELUC replacement air heaters are installed adjacent to the wall and the replacement air for heating is brought to the heater from outside through a short duct. GC and ELUC heaters are especially well-suited to decentralised replacement air heating, where there are several heating units. The combustion gas of the heaters can be lead directly to the heated space or alternatively ducted out through the wall. The heaters are also suitable for spaces where the air is dusty or otherwise dirty.
MARK GC and Combat CTUC replacement air heaters are, in practice, very similar to the ELU and GC circulation air heaters. The main difference is that in the replacement air heaters there is a centrifugal fan which produces a stronger flow of air. The circulation air heaters normally have a lighter axial-flow fan.