Re: Heating crawl space
If you properly insulate the joist bays, AND if your pipes are sufficiently protected from freezing (ideally they should be run up in the joist bays, encased in the insulation), AND you have adequate ventilation in the crawl space, moisture shouldn't be a concern.
However, since you live in Michigan where it gets (insert colorful word here) cold, you may not want to leave the vents open when it gets down into the teens or lower.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.