Can I use a HEPA filter in my furnace?Updated a month ago

We wouldn't recommend it. HEPA filters are able to filter out even the very smallest particles. Because of that though, it's hard for air to pass through HEPA filters, which doesn't make them a good option for your whole-home HVAC system. By not allowing proper airflow, you can "strangle" your unit and cause severe and costly damage. 

All Windmill Filters are designed specifically to remove microscopic contaminants. However, if you would like to use a HEPA filter, we recommend buying an air purifier and using it in specific rooms only, or looking into the Medical Windmill Filter, which is our highest filtration product.