Good tip. I have a heat pump (hate it) and use the allergen filters. While it may cut down on dust, I still sneeze a lot. A little story about furnace filters and a good friend of mine in another state. She was recently divorced and I would occasionally make the 6 hour drive to spend a weekend with her. She was telling me about her ridiculously high electric bills. I asked her if she had changed the furnace filter recently. She said she didn't even know where the filter was. We went to the basement and I showed her where the filter was and how to change it. I was shocked when I pulled the old one out. It literally looked like it had a coating of tar on it! Completely black. Almost looked like it was black plastic coated. We went to Walmart and picked up a pack of filters and I told her to get into the habit of changing the filter every month, even if it didn't look bad. They're cheap. I have never in my life saw a filter that looked like hers. It was obvious her ex hadn't changed it either. I'm surprised there was any air at all coming out of the registers. If you know someone who may not know about filter change or how to do it, maybe an elderly person, take a few minutes to check their furnace out. To most of us, it's a simple habit. But to some, like my friend, it may be something they aren't even aware of.

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Misty