Maintaining your furnace
It’s that time of year when the days and nights are getting cooler. You have had the opportunity to keep your windows open after the summer heat and let the fresh air in your home. Now it’s time for furnace to get to work and keep you warm.
Today, we’re going to talk about taking care of your furnace. It’s easy to ignore. It sits out of the way in the basement, and you expect that when you turn the thermostat up, the furnace responds. Having to replace or repair a furnace can be expensive. Murphy’s law seems to apply to furnaces. You won’t notice that there is a problem with your furnace on a mild, fall Monday morning- it will happen on a sub-zero Saturday night.
One of the most effective, cheapest and easiest maintenance items that you can do is change the furnace filter regularly. I inspect many homes that have furnace filters that don’t look like they have been changed in years, or even some that there is no filter at all.
The frequency that you change filter depends on a few different factors. First is the thickness of the filter. The filters range from 1” to 6” thick. If you have a 1 or 2 inch filter, it is recommended to change it out monthly during the heating and cooling seasons. Filters that are 4-6 inches can be replaced either once or twice a year. That brings up the second factor. If you have pets, or have any people in the home that have allergies, you may want to change the filters more often.
When you buy filters, they have a MERV rating on them. MERV is an acronym for Minimum Efficiency Reporting Value. The ratings range from 6-16 and they rate how efficiently they remove dust and particles. The higher the MERV rating, the more particles they will remove from the air. People tend to think that they will simply get the highest MERV rated filter to remove the most dust and particles from the air, especially if someone in the home suffers from allergies. However, in a residential furnace, a MERV 13 is the highest rated filter that should be used. In speaking with HVAC technicians, they state filters with a MERV rating of 8-11 is ideal for furnaces.
The problem with higher rated filters is that, although they do filter out more particles, they also restrict air flow because of the density of the filter. And because they are denser, they need to be replaced more often. The problems that HVAC technicians see with the higher rated filters, is that the furnace is designed to operate at a certain air flow. When a higher rated filter is installed, it causes the furnace to work harder and, in turn, makes the furnace less efficient. In time, this can cause premature failure of the blower motor, or the furnace may simply shut down due to the lack of air flow.
My recommendation is to have your furnace and air conditioner serviced annually. You can find HVAC companies that will provide this service for around $100. They will clean, adjust and inspect the furnace for many different issues. Another recommendation is, if you’re furnace has electronic ignition, meaning that there is no standing pilot light, get the model number from your furnace and order an ignitor. This is a common problem with electronic ignition furnaces. The ignitor typically costs between $25-50 and they are specific to each furnace, so your HVAC company may, or may not, have the part you need when it fails. My theory is that if you have the spare ignitor and set it near the furnace, the installed ignitor will never fail!
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Tim Williams is the Certified Professional Inspector® with Timberland Home Inspections.