Even though many new furnaces come with 20-year extended heat exchanger warranties, they should still be checked yearly even if they seem relatively new. This month alone, our service and maintenance department found at least 8 bad furnaces still under warranty, 5 of which were less than 10 years old all having heat exchangers requiring replacement. In many of the cases, the problem was caused by either the owner neglecting his filters, or by how the original contractor installed the equipment. In many cases, we find that the furnace had never been tuned up or set-up correctly from the day of installation.
Too large of a furnace will constantly go on and off causing excess wear and an early death. Just like the starting and stopping of a car from "city driving" will also wear a car out prematurely.
Typically, they are not used to determine your property taxes. However, not all contractors pull their required permits. Since the contractor must legally pull a permit for every furnace installation, it's a good idea to verify that he did by calling your city or township a week or so after the job is done. This way, if you do have a problem in the future, you have greater legal recourse available to you.
Although many people do this to help protect water pipes from freezing, they tend to forget that any air taken from the house and blown elsewhere must be replaced back into the house. Normally, the air that replaces it is forced from the area the register blows into. This will cause the dirty and probably moldy crawl space air to come up into the house where it will wreak havoc on allergies. If the register goes into the garage, you have the potential to suck exhaust or chemical fumes from the garage into the living area of the home.
In over 90% of the occasions where we are repairing frozen lines, the problem can be traced back to an open vent door or a crack in the foundation where the wind can enter.
Over an eight hour period you can save 1% for each degree you set your thermostat back. For example, setting back your thermostat to 65° Fahrenheit each night can shave 5% of your monthly gas bill.