There are many different ways that a person can save money when it comes to HVAC, for example if you are looking to buy a brand new furnace and don't know who to go to just go online and search some of the better ac/furnace installation companies and check if they are on better business bureau. Once you have checked that and you know that they are a good company, just have them come by your house and give you a quote on how much the total cost would be. Another way of saving money is always keeping your furnaces air filter clean, it should be changed every 4 weeks, and sometimes you don't even have to change it you just have to clean it!! so your saving double the money. The cleaner your furnace is the easier and less energy is required from your furnace which will help you say money. None the less it is always better to buy the variable furnaces because they save you almost double the money. Last but not least always keep your ducts clean, it will make it easier for air to travel through which again would be less energy being used by the furnace to heat or cool the house.