Where are this flys coming from
Potted plants inside the house with soil that is not allowed to dry can be a source of small flies. Take all your houseplants outside and let them sit where they get some sun for a day or two, to dry out.

I have seen nasty maggots and flies in old sewer drains that are plugged or partially plugged, or that are left unused for long periods. Check all your drains; run hot water down through them. Check your basement if you have one.

Are your window screens and screen doors in good order? Flies will come into your house from outside during hot weather.