I know a few people on this site seem to know a good bit about HVAC systems. So, I thought I would check here. Do they make a thermostat that you can program the fan only to come on? I would like to kick on the systems fan every hour or so for a few minutes to help draw the dust into the air filter. I don't use the system for heat as I have a pellet stove. So, I try to remember each winter to kick the fan on periodically to clean the air some. Summertime the A/C typically kicks on often enough to keep the dust down.