If you have a musty wet basement and have a air return in your basement which since you are running your fan 24/7 will pull that odr or musty smell from your basement and crawl space.Believe it or not I just came from my parents home and when I walked in they had a very strong musty odor which was coming from there basement because it is alittle damp but they had a small cold air return which was sucking in the odor from there basement and spreading it thru out there home, so I closed it off and turn the fan on high for about a hour and opened a few doors and windows and the smell was soon gone. If you do close it off and see what happens after a hour or so with the fan on high and fresh air allowed to circulate thru out the home and see it that helps with the odor your claiming your home has. These lights are very powerful ultra violet radiation lights that kill dust mites bacteria and mold.It seems to have gotten so much worse from the partial cleaning we got in July, which left a thick coating in one return and small piles in the other.Very humid or rainy days make it almost unbearable to breathe.Maybe you can get some money back since they did not clean the AHU.
Noticed a marked improvement for about a week, but still had an off dirty smell.
These are not an inexpensive fix but will improve the air quality in your home.
(cheaper than a hepa and better on your blower motor, heat exchanger, etc etc etc...) - "If you were able to chose the kind of brain injury you were to incur, it would be better in terms of the potential for recovery to have a stroke, concussion in a motor vehicle accident, etc.
Environmental company believed we could have a dead animal in the return flex in the attic, thus the differences in smell with heat and humidity.
Upon thorough investigation of the attic and the flex they could find no signs of mice, breaks in the flex, or water and mold in the attic.
Have been dealing with layers of odor from HVAC system for the last 3-4 months.