A furnace is simply speaking, is a device used for high-temperature heating. There are various types of furnace based upon the fuel that it uses and in each of the cases, the installation could be different as different fuel needs different structures to work.
For example, a combustion furnace is very different from an electric furnace and due to this; the whole setup could be very different. And it will need different equipment, different fuel, different setup and different workload. Not to mention, the cost of running and maintenance will also vary from one furnace to another.
For example, a gas furnace is just a box shaped heater with some tubes connected to it to convey the heat. The principle of this is very simple. Cold air will come in and hot air will go out. Thus, a gas furnace is very simple in building wise or structured wise and hence probably easier to understand.
While installing a furnace, a few things need to be considered. First is, it must be energy efficient. For example, the furnace should be At least 90-94% efficient while warming with combustion from the fuels. Otherwise, that furnace will be just a waste of money and resources. There are plenty of Furnace Installers in BC who can provide you energy efficient furnaces for your house.
Since 100% efficiency is unattainable, there must be boundaries to draw when it comes to using fuel into a furnace. And generally, this efficiency is in the range between 90-94%. Any big deviation from this will result in an inefficient furnace which won't live up to the expectations or it may become very hard to accommodate.
Suppose you are installing a condensing furnace. Then you will need a speed blower which should be dynamic in nature. It simply means the blower should be manageable so as to maintain different heat level. Otherwise, the furnace will maintain a constant heat depending upon the fuel and the combustion and there will be no way to increase or decrease the temperature of your choice.
Excluding the blower, you will also need a return air box. This box will simply act as the air container to whom you will connect all the air ducts.
Since all the air passes through it, it makes the perfect structure to put an air filter in so that, while going through the return box, the air filters out.
After that, depending upon the fuel, you will need to setup different types of structures in the furnace. What you use for a gas combustion furnace will be very different from electric furnace and will have to build accordingly.