I recently purchased a house with ICF walls and a conditioned crawl. When I was checking out the crawl space it has a air supply from the HVAC unit, BUT it also has a air RETURN.
Is having an air return in a conditioned crawl space okay,safe and or normal???? Thanks for your help

In many jurisdictions, a crawl must be conditioned space(requiring both a supply and return) or all the duct within should be insulated so it is not uncommon practice. The only places returns are generally dis-allowed in residences are kitchens, baths and areas from which combustion air is gathered (i.e. mechanical room). Common pratice is also to avoid laundry rooms.

One old practice used the crawl space as a return air plenum. Still permitted in many municipalities as long as vapor barrier is in place and walls are insulated, return air grilles would simply be placed over a hole cut in the floor and the furnace would draw return air from the crawl.

Pressuring or depressurizing any space will cause leakage (to the outdoors). So you want a supply and a return in almost any closed area - properly adjusted to produce a neutral pressure.

Yet another way to warm your floors!

Thanks for your replies! Makes me feel way better!