The key element of the whole system is the air heater (gas air heater), to which the supply air duct is connected. Other ducts lead from the same space and return the air to the furnace chamber for reheating.In other words, the system runs on recirculated air. If necessary, a special damper can be used to draw in outdoor air. This modification solves two problems at once:
raising the temperature in the rooms;
ventilating them.
Heating air heaters can be used with special furnace filters installed in front of the heater; their main purpose is to trap dust and fine dirt. If air cooling is needed, evaporators can be connected to the system, while the compressor-condenser unit is installed outside the building. The temperature can be regulated by a thermostat that maintains the set parameters.A well-designed system solves many tasks related to heating, ventilation and air conditioning — and only one piece of equipment needs to be installed. To heat a very large area, more complex and powerful units are the better choice.Their special feature is that a single unit combines:
a compressor;
an evaporator;
a condenser for air conditioning;
a gas heat exchanger for heating;
a damper system for mixing in fresh air;
control automation.
The operating principle is exactly the same as in the system described above. Heating air heaters are designed so that they can be used both in new buildings and where existing heat supply systems need a major upgrade.
Air heaters: types and kinds
Heating air heaters can be classified by fuel type.Gas.This equipment is the most popular in its market segment. It runs on liquefied and mains gas. The main advantage is 100% combustion of the fuel without any residual combustion products. Gas is much more environmentally friendly than other fuels. Efficiency is 91%, the highest among all heat generator modifications. The units are sold in two configurations differing in heat exchanger type: closed or open. The closed model is safer but more expensive than the open one.Diesel.The unit is fuelled with diesel, which may be replaced with kerosene. There are two versions differing in nozzle type and diesel feed method: drip or atomising. The latter ensures perfectly even atomisation throughout the combustion chamber.Multi-fuel.These units can run on any fuel: vegetable or animal fat, waste oil, diesel. Such industrial heat generators are installed mainly at sites that need to process or dispose of oil and fats. Output is much lower, and slag may form after combustion. For this reason the models have two combustion chambers, so one can be cleaned without interrupting operation while combustion continues in the other.Solid fuel.These units combine a classic stove with a diesel or gas unit. They are equipped with a fuel chamber, grates and a reliable door. Firewood, coal and wood pellets can be used as fuel. Efficiency is 85%. Before buying, bear in mind that installation requires a lot of space and the combustion chamber must be periodically cleaned of accumulated slag.Vortex.The unit needs antifreeze or water to operate; they convert electrical energy into heat.Stationary units are divided into suspended and floor-standing. Suspended units are compact and can be installed outside or inside a building, on wall brackets or on the roof. Floor-standing hot air heat generators can be horizontal or vertical; horizontal ones are suitable for low-ceilinged rooms.
How to choose: what to look for
When buying heating air heaters, first consider the heat exchanger diameter. The best choice is one whose heat exchanger diameter is 1/5 larger than the burner. The output of a heat generator depends directly on the amount of kJ needed to reach a certain air temperature. The optimal option can be determined based on:
the floor area;
the thermal insulation of walls and ceilings;
the number of gates;
how often they are opened;
the climate of the region;
internal heat gains.
An accurate heat calculation can significantly reduce overpayment for excess or insufficient output. From the above, it follows that when choosing a heating unit you need to answer a number of important questions.
What output is optimal?
Where will the air heat generator be installed?
How exactly will it be installed?
Does the unit need to be connected to a duct system?
Where will the duct connection be?
Which fuel is preferable given the cost of air heating?