Norm Rollin came to do the maintenance on my almost year-old furnace. He did a great job and gave me advice on when and how to clean and when to change the allergy filter. I'm to vacuum it quickly once monthly and rinse it with just water every three months, allowing to dry for a day. I'm to use a 3M filter ($6-7) – from Cdn. Tire, etc., for a day while allergy filter drying. I didn't know, but allergy filters will last years. He also told me something I didn't know - I'm not to use the allergy filter all year. The 3M filter is the one to use in the summertime from the time I turn the heat off to the time I turn it on in the fall. Note that the allergy filter is quite expensive - 87.05 before taxes - so the advice was valuable. Also, I wouldn't have known in which direction to install the filter. Norm marked the direction on the furnace and told me to ensure that the arrow for “air flow” was pointing to right. Also, he asked me why I had the furnace fan on the thermostat set to high. I told him that different parts of the house were different temperatures. He checked the cold air returns upstairs - we have a split-level house - to ensure they were open. Lo and behold, the upstairs bedroom returns were closed for years. He showed me how to open them and to ensure that the pin was up all the way for the return to be closed. In fact, he recommended I remove the pins so that the returns are always open. The furnace installers last year told me I should put a cup of vinegar in the water system to keep it clean. Norm told me where to do so as he thought it was a good idea. If you decide to go with Holmes (they were in my opinion the first company to use the small machine vs. the truck and hose to clean ductwork), ask for Norm Rollin.