You may have heard of a variety of potential services or additions you can install in your HVAC system or elsewhere in your home that will boost air quality. Here are some of the available options and their pros and cons. WHOLE HOUSE HUMIDIFIER Average cost: $530 Where you might need it: Particularly dry areas Humidifiers, which keep your air moisture balanced, come in a variety of models. Steam units are usually the best to use in a residential ...