It's not unusual for an HVAC technician to be called out to repair a furnace, only to find the problem is a filter that's gathered so much dirt and debris that it looks more like a household pet than a functioning filter. These service calls are unnecessary and expensive, especially if they happen after hours or on the weekend. Whether you own or rent, maintaining clean furnace filters will provide a cleaner living environment for you, and help reduce utility costs and repair bills.
Filters allow air to circulate freely through the ventilation system, while preventing the dust and dirt in the air from damaging the furnace. If not changed appropriately and allowed to accumulate too much debris, filters no longer server their protective function, and this can lead to bigger problems down the road.
Here are a few things to keep in mind when debating if it's time to time to change your furnace filter.
1) Filters protect both you and your furnace.
The furnace's fan is moving extremely rapidly, and excess debris can clog it, making it run less effectively or even damaging it. Filters take dirt and debris out of your home's air supply, and (depending on the type of filter) can do wonders to help people who suffer from allergies.
2) Clean filters mean warmer heat and cooler a/c.
Whether heating or cooling, furnaces work by moving air, and if a filter becomes clogged, the furnace can't do its job. Your home may continue to warm/cool for some time, but as the furnace struggles to pull air through its system, maintaining an appropriate temperature will become more and more expensive, and eventually it may not function at all.
3) Furnace Filters are inexpensive, and easy to change.
While there is a great deal of variety in size, thickness, and effectiveness of furnace filters, they all basically function the same way. If you have a thicker filter or one with a finer mesh, you'll pay more up front but you'll be compensated by more effective filtering and longer times between filter changes.
Most modern furnaces have a slide-in furnace rack, from which you can simply slide out the old filter and slide in the new. However, some units have the filter housed directly in the furnace blower compartment, in which case you turn off the power to the furnace and open the compartment door to access the filter. Often in these units there is a metal arm or bracket designed to keep the filter from tipping over. While these arms can be tricky to get in place, it's just a matter of balance, and not an issue of technical knowledge.
When you place the new filter, make sure it's facing in the right direction. Any good filter should have an arrow indicating how it should be orientated in the filter rack or blower compartment. (The arrow should point towards the furnace blower.) And regardless of the type or location of your filter, it's a good idea to write down the filter size on the furnace itself, and write the date you installed it on the end of the filter that will be visible when it's in place, so that you don't have to second guess yourself when it's time for a new one.
Keep these facts in mind, and keep the maintenance costs to a minimum!