There are many things to consider when buying a gas furnace, and getting them right is essential in order to get the furnace that will heat the house to a good temperature, but will also be easy to operate.
It may seem to be a difficult choice, but by following a few guidelines the choice can be made much easier.
The first thing to consider is the heat output of the furnace since this will have a great effect on how warm your home becomes, and if you are running a combined heating and hot water system, how much hot water you will have for the bath and so on.
For a small house or apartment, a heat output of about 40,000 BTU should be sufficient, though once the house sizes rises to a four-bedroom or so, you need to look at a bigger model, such as a 75,0000 BTU or thereabouts.
The next consideration should be the ignition system.
This should almost certainly be an automatic type, enabling the heat to be supplied very quickly, even from a cold start on cold winter mornings.
This is essential for a comfortably heated home.
Along with the ignition type, a programmable thermostat should be an essential.
But not just a simple model, but one which can program the heating to a high degree of accuracy to ensure the temperature is always at an optimum level.
Finally, take a look at gas condensing models, since these will often run at a very high-efficiency, meaning they not only keep you house warm, but can also save substantially on heating costs.
Keep all these simple factors in mind, and purchasing a furnace becomes much easier.